WO2016094521A1

WO2016094521A1 - Mobile polarized-imaging platform for point-of-care diagnostics

Info

Publication number: WO2016094521A1
Application number: PCT/US2015/064712
Authority: WO
Inventors: Casey W. PIRNSTILL; Gerard L. COTÉ
Original assignee: The Texas A&M University System
Priority date: 2014-12-09
Filing date: 2015-12-09
Publication date: 2016-06-16

Abstract

A mobile imaging system and method includes a mount for a mobile device and a sampling module. The mount includes an attachment point that permits different sampling modules to be attached to the mobile-imaging device to permit both transmissive and reflective imaging analysis to be performed. The transmissive analysis may be performed in conjunction with a standard blood smear on a slide or with a microfluidic sample cartridge. The reflective analysis may be performed on, for example, a patient's skin.

Description

MOBILE POLARIZED-IMAGING PLATFORM FOR POINT-OF-CARE

DIAGNOSTICS

CROSS REFERENCES TO RELATED APPLICATIONS

[0001] This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application No. 62/089,819, filed December 9, 2014, which is incorporated herein by reference in its entirety as if fully set forth herein.

BACKGROUND

[0002] Conventional light microscopes have played a significant impact in improving understanding of disease in addition to improving the ability to diagnose diseases. Polarized microscopy has been utilized for decades as a tool to improve biological imaging and medical imaging capabilities. Overall, the state of the field is very encouraging for polarized microscopy to improve diagnostic approaches to various diseases, such as malaria. However, implementation of polarized microscopy and imaging systems are often inhibited from widespread use because of their complex design, the requirement of sophisticated maintenance, their bulky size, and their cost. For these reasons, it has not completely matriculated into the clinic, is not useful for remote or point-of-care (POC) monitoring, and is rarely used in developing countries, specifically in remote areas. Providing easily translatable, polarized light microscopy imaging capabilities into the clinic and field in both remote and local settings would make this diagnostic tool more accessible and increase usage. An increase in utilization could greatly increase the research applications and diagnostic capabilities for several disease states. This would significantly impact treatment options, limit dispensing of unnecessary drugs, such as those for treating malaria, and potentially increase the life expectancy for people with such diseases.

[0003] Polarized imaging has also provided a technological basis for several forms of disease diagnostic imaging, allowing for diagnosis to occur at earlier stages in the disease cycle. Thus, a need exists for the implementation of these polarimetric imaging techniques to be integrated into a system which is capable of permitting widespread usage. Such increased usage of polarized imaging techniques could significantly improve disease diagnostic recognition for several diseases states as a POC based device. [0004] In recent years cell phone based microscopic techniques have been explored for use in the analysis of water sources for potential contamination, particle tracking for fluorescence cytometry applications, and to evaluate blood smears for diagnosing diseases such as malaria, tuberculosis (TB), and sickle cell anemia. Other cell phone- based health care applications have also been proposed such as Otoscope, EKG, PCR, and Ultrasound, the measurement of refractive index errors and cataracts of the human eye. Due to the large volume of wireless communication users, cell phones continually remain at relatively low cost even with their rapidly improving hardware and software specifications. The increased access to mobile networks and cell phones containing advanced photographic capabilities and other technologies have made cell phones ideal for many advanced imaging and sensing applications including mobile/remote health monitoring for diagnostics. The features of the cellular platforms offer the opportunity for improved healthcare through low-cost, high quality, portable, energy efficient alternatives to existing imaging modalities. This is particularly important for the clinic, remote areas, and in the low resource settings where the medical infrastructure is often times limited or even non-existent.

[0005] It is well known that in many cases malaria can be diagnosed with the use of polarized light imaging. According to the WHO, an estimated 665,000 deaths were caused by malaria in 2012. The WHO also estimated 219 million new cases in that same year. Studies have shown that polarized microscopy is an acceptable method for identifying malaria, and may be superior to conventional staining. This is particularly true for less severe cases of malaria. It has been demonstrated that when examining histological specimens, polarized microscopy is approximately twice as sensitive as conventional light microscopy for detecting the malaria parasite. The conventional staining approach is also potentially inferior since it can also include many false positive indications.

[0006] Although, conventional microscopy and staining works well in severe cases of malaria, they are often unsuited for less severe cases that are harder to diagnose. As shown through comparison of the polarized and conventional images, staining can also provide many false positive indications. Polarized microscopy has been shown to be more accurate in many cases since the changes are a result of birefringence due to the presence of hemozoin. In fact the contrast comes from the birefringence of the malaria parasites, which produce a pigment known as hemozoin crystals during hemoglobin digestion. The presence of hemozoin, as an indicator of malaria parasites, can be observed via polarized light. As suggested above, some studies utilizing conventional microscopy for diagnosis have reported conflicting results suggesting imprecision and inaccuracy in the technique. However, Giemsa staining of blood smears still remains the gold standard for malaria diagnosis in spite the emergence of these optical techniques. While rapid diagnostic tests are improving in specificity and sensitivity, they usually are only able to detect a single type of malaria and cannot differentiate between types, or when multiple types are present within a subject.

[0007] Spectroscopic analysis may be used to analyze biological tissues in vivo and in vitro. Recording and analysis of spectral signals from tissue can provide detailed information regarding the physical composition of the target tissue as well as the state of individual physical components. Many molecules may have unique spectral signatures. For example hemoglobin may have distinct spectra depending on its oxygenation. The difference in the spectra between oxygenated and deoxygenated hemoglobin has been used in multispectral and hyperspectral methods to determine the oxygen content of retinal arteries and veins.

[0008] Polarization is a property of electromagnetic waves that describes the orientation of their oscillations. The orientation of the electric fields of electromagnetic waves emanating from a surface may or may not be correlated resulting in various states of polarization. Measurement of these polarization states has provided useful information regarding some biological targets. Analysis of polarization anisotropy in tissue structures has been limited because of the technical limitations in polarimetry. Despite the advancement noted in polarimetry, limitations still remain. For example, typical polarimeter instruments are commonly limited by the need to manually adjust settings, slow acquisition times, limited field-of-view, and insufficient dynamic range. A relatively small field-of-view and a long acquisition time can necessitate significant effort in image registration and analysis. In addition, polarization of light is also subject to the same sources of noise as described above for spectral imaging. These limitations likely place an upper limit on the clinical sensitivity and specificity of commercial polarimeters and other polarization measurements. [0009] There is a significant need for the improved early diagnosis of skin cancer events and malaria (especially in remote, low resource, settings) to increase the probability of survival within demographic populations where the disease is present. According to the World Health Organization's (WHO) 2012 cancer fact sheet, cancer is the leading cause of death worldwide accounting for over 7.5 million deaths in

2008. Basal cell carcinoma (BCC) is the most common form of skin cancer, with an estimated 2.8 million people diagnosed annually and is most common in Caucasians, Hispanics, Chinese Asian, and Japanese demographics. However, after the disease reaches the lymph nodes the rate drops to 62% followed by a drop to 15% survival rate if metastasis to distant organs occurs. Melanoma is less common in African

Americans, Latinos, and Asians. However, when it does occur it is frequently fatal to those populations.

[00010] Thus, the development of an inexpensive, high quality, portable, noninvasive, optical polarimetric imaging system, integrated with a commercial mobile-device camera for preventative screening can provide the necessary diagnosis to improve early detection of skin cancer in a wide variety of settings including clinics, remote locations, and developing countries. This in turn could greatly facilitate an increase in survival of skin cancer patients in all demographics.

SUMMARY [00011] A mobile-imaging system and method is described that is a noninvasive, low-cost, mobile-device-based polarimetric-imaging system capable of achieving both macroscopic imaging and microscopic imaging with high quality optical resolution comparable to larger bench top polarized microscopy systems. In general, there are many conditions known to induce changes in polarized light as it interacts with the sample. In an embodiment of the invention, the polarized imaging platform described herein could be used to assist medical professionals in the clinic and in low resource settings in the proper diagnosis of conditions such as skin cancer and malaria. For example, the polarized macroscopic imaging device can be used for in vivo diagnosis of skin cancers such as basal cell carcinoma (BCC), melanoma, and squamous cell carcinoma (SCC) and in vitro detection of malaria in the lab or in the field. [00012] The mobile-imaging device includes a polarized transmissive-based optical configuration to analyze the blood smears at the microscopic level for the detection of malaria with or without the addition of histological stains. The mobile- imaging device transmits polarized light (white light or any color or wavelength depending on the application) through the sample slide and then images are collected with the analyzer oriented at any angle or at two angles with respect to the initial light source polarization to maximize the contrast for both red blood cells and the parasite as well as the birefringent hemozoin from the parasite. A removable cartridge (see FIGS. 4A-4D) allows for transmission-mode polarized microscopy. The transmission- based cartridge setup is capable of imaging a blood smear inserted into the optical path. A slide rack is located in the mobile-imaging device such that the sample is optimally positioned at a focal length of the imaging system. The system allows for the option of a mosaic image of an entire sample (e.g., using a panoramic view of a mobile-device with electronic or mechanical scanning) or an individual image of a specific region within the sample. The system is similar to a conventional high quality polarized microscope for imaging a microscope slide, however the system fits into the hand of the user and provides visualization and processing of images through a mobile-phone designed application to provide automated prediction of disease states present in addition to the type(s) of disease present (i.e. presence of malaria and, further, type of malaria).

[00013] In some embodiments, the mobile-imaging device includes a means of mechanically moving the slide to obtain different fields of view. An alternative embodiment would include an automated deformable mirror chip that allows for the illumination beam to be steered into specific locations which each have an image that is then individually collected via the optics described and imaged by the mobile device.

[00014] In some embodiments, the mobile-imaging device uses on-chip holography to improve a field-of-view (FOV) and reduce the number of required optical components in the sample. In this configuration, the sample (e.g., the sample, a microscope slide, or an automated microfluidic chamber) is placed between two polarizers. One polarizer is placed between the phone and sample slide and the second polarizer after the sample is followed by a light source allowing for transmitted polarized light to traverse the sample.

[00015] The sample attachment portion of the invention may comprise an automated microfluidic sample chamber or cartridge (e.g., see FIGS. 4A-4D). Alternatively, the sample attachment may comprise a traditionally prepared blood smear on a microscope slide. In some embodiments, the sample attachment is a microfluidic sample chamber. The microfluidic sample chamber may include a vacuum sealed chamber with an input port that can be broken for sample insertion via a standard gauge needle. Following the input path a narrow channel exists allowing for the inserted sample to be dispersed via capillary motion across a fixed height, width, and length for imaging. Additionally, after the sample is prepared and fixed across the prepared chamber the sample can optionally be submerged in a biological staining agent to allow for optimized viewing of many characteristics within the sample.

[00016] In some embodiments, the microfluidic sample chamber includes an open input port that accepts a sample by being placed in contact with blood or by placing a drop of blood into the open input port. This allows the sample to flow through a narrow channel via capillary motion across a fixed height, width, and length for imaging. A pump mechanism can also be used to manually pull the sample through with excess being accumulated in a waste chamber. Additionally, after the sample is prepared and fixed across the prepared chamber the sample can optionally covered with a biological staining agent to allow for optimized viewing capability of many characteristics within the sample. This stainging agent can be applied after the sample has dried using an actuator that can be activated to release the staining medium onto the sample for preparation.

[00017] In some embodiments, the microfluidic sample chamber comprises two areas or chambers on a single chip, one chamber for a thin blood smear and an additional chamber for a thick blood smear. Additionally, each sample microfluidic chip is capable of allowing the sample to be prepared and fixed onto two separate locations each of different heights, lengths, and widths. The input port is still a single port, which is then separated into the two chambers. Additional sample volume is collected in a waste reservoir. [00018] The embodiments described above would permit low-cost, image- based diagnostics at the point-of-care, physician office labs, in the clinic, and in the field. One example of point-of-care diagnostics is that the presence of a birefringent byproduct of malaria, hemozoin, could be assayed for diagnosing malaria. Additionally, disease recognition that can be enhanced with polarized light can be evaluated improving diagnostic capabilities with the invention.

[00019] The transmission based cartridge is capable of acquiring mosaic or compilations of slides providing a significantly larger FOV than conventional systems. Image processing and analysis of the sample being analyzed are programmed into the phone to extract features such as the presence of birefringence or polarization variations for disease diagnosis (i.e. malaria or no malaria) and color, size, and shape of the parasite and red blood cells, with or without staining, for disease characterization such (i.e. malaria typing) so that appropriate interventions and drugs can be used.

[00020] In some embodiments, the mobile-imaging device includes a polarized reflective-based optical configuration to analyze skin for the detection of skin cancer. The mobile-imaging device configured for reflectance mode polarized imaging and comprises at least one light to provide reflective illumination of an area to be imaged. The mobile-imaging device includes a mount adapted to secure a mobile device and to set a focal length L to be located at a subject's skin. A first polarizer is placed in the optical train such that the polarizer covers the at least one light but contains an open center portion that allows reflected light to pass through a macro lens, and eventually the camera of the mobile device. In some embodiments the at least one light may be patterned at a 25° angle off axis with respect to a light-collection path. In some embodiments, multiple lights may be disposed around a circumference of the macro lens. A second polarizer that is oriented at the same angle with respect to the light source is placed into the optical path. The second polarizer may be movable into and out of the optical path. A third polarizer that is oriented 90 degrees with respect to the first polarizer is placed just prior to the camera of the mobile device. Utilizing the mobile-imaging device configured for reflective-based imaging, a series of images can be acquired with the intensity setup in perpendicular polarized mode and parallel polarized mode for image analysis and margin enhancement for improved diagnosis of potentially cancerous areas.

BRIEF DESCRIPTION OF THE DRAWINGS

[00021] FIG. 1 is a diagram illustrating an approach to detect a presence of polarization changes in an image sampled in a transmission-based configuration that measures changes in rotation of a plane of polarization of polarized light that passed through the sample;

[00022] FIGS. 2A-2C are CAD renderings of a transmissive-based mobile microscopic imaging device according to an exemplary embodiment of the invention;

[00023] FIGS. 3A-3C are CAD renderings of a reflective-based mobile- imaging device according to an exemplary embodiment of the invention;

[00024] FIG. 4A is a diagram of a microfluidic sample cartridge showing top and side views of a non-vacuum sealed configuration according to an exemplary embodiment;

[00025] FIG. 4B is a diagram of a microfluidic sample cartridge showing top and side views of a configuration including an open input port according to an exemplary embodiment;

[00026] FIG. 3C is a diagram of a microfluidic sample cartridge showing top and side views of a vacuum-sealed configuration according to an exemplary embodiment;

[00027] FIG. 4D is a diagram of microfluidic configuration showing top and side views of a configuration that includes two sample reservoirs according to an exemplary embodiment;

[00028] FIG. 5A is a graph showing calculated Gaussian fit and derivative function for a line spread function placed halfway across Group #2 Element #4 of a standard Air-Force-Target; [00029] FIG. 5B is a graph showing calculated Gaussian fit and derivative function for a line spread function placed halfway across Group #5 Element #1 a standard Air-Force-Target; and

[00030] FIG. 6 is a graph showing Gaussian fit and derivative function for a line spread function placed halfway across Group #2 Element #1 a standard Air- Force-Target.

DETAILED DESCRIPTION

[00031] Embodiments of the invention focus on a means of developing a low- cost, portable, mobile-device based polarimetric imaging system. Embodiments of the system would be used for applications including noninvasive early screening and detection of malaria and skin cancers (e.g., BCC, SCC, and Melanoma). Thus, the proposed technology has the potential for enormous benefit to society, particularly in low resource settings, in addition to commercial clinical potential. Current screening methods for skin cancer and malaria can often be costly, thus, limiting the use and effectiveness of such techniques in remote and low resource settings where implementation is not feasible. The mobile-imaging system offers an easily printable plastic attachment mount that includes a low-cost lens and polarized light configuration for a mobile device, such as, for example, a cellular phone, tablet, or digital camera, to allow for high quality macroscopic or microscopic imaging that is comparable to conventional screening methods. The proposed mount attachment and lens configuration, in addition to design of a software imaging application, would therefore offer a low-cost commercial product available for implementation in remote and non-remote areas alike. Additionally, by utilizing a mobile-device camera, the images of the regions of interest on a subject can be acquired by a non-skilled professional, processed, and analyzed automatically via software to provide suggestions/recommendations to the user. Additionally, the acquired images can be transmitted to a medical specialist or group of medical specialists anywhere in the world via the software imaging application for further diagnosis. Overall, the envisioned technology provides two commercial products and one potential service (remote diagnosis via a medical specialist or group of medical specialist) to a demographic that is currently lacking early diagnostic capability for the medical conditions described above. [00032] Key advantages of a mobile-device-based polarized-white light imaging over established cell-phone based imaging techniques are that research has shown polarized microscopy has significant advantages assisting with diagnosis of certain cancer types in addition to other disease states. Polarized imaging can provide enhanced contrast of a sample comparable to conventional histological staining techniques. However, unlike staining this technique can be accomplished immediately, speeding up surgical decisions in addition to reducing complexity of steps.

[00033] In addition, with imaging for mobile-device-based design, there are several key advantages to using polarized white light imaging over utilizing conventional bench top microscopic systems. The main advantage is the reduction in cost associated with conducting the approach on a mobile platform. This greatly increases the potential applications and portability for the technology. This, in combination with proper use of imaging software or mobile applications (APP), can also make the system more user friendly and not require the need for highly trained microscopy personal.

[00034] The APP for image acquisition and analysis is designed to support the multiple hardware configuration capabilities of the mobile-imaging system described herein. Regardless of the configuration choice, the user has the ability to control many of the camera features on the mobile device to optimize the quality of the region to be imaged prior to acquiring the picture. The APP allows for control of features such as manual focus, shutter, exposure time, image stabilization, ISO setting, and lighting. Processing algorithms in the APP are capable of providing the user with relevant polarization information in addition to the processed images. Additionally, the APP provides the option to request a medical expert or group of medical experts for their opinions on the data complimenting the field analysis. The user may choose between single acquisition of an area on the blood smear or histological slide or potentially utilize a panorama option allowing the acquisition of a mosaic image of the entire slide with either a mechanical translation or electronic transformable mirror configuration. After image acquisition the software performs multiple algorithms to optimize the image quality for easier automated analysis/detection of disease. [00035] For skin cancer diagnosis, the application will prompt the user to acquire two polarized images at two different polarization states. In one embodiment, a parallel polarized image of the suspect area on the subject's skin and then a cross- polarized image. Following acquisition the two images will be processed using the intensity relationship illustrated in Equation 1 that is described below. The mobile device will then display the processed image indicating potentially hazardous regions in addition to the raw un-polarized image of the specimen. The software will then employ boundary recognition algorithms during processing to generate automated boundary recognition results to aid in margin detection and diagnosis of hazardous regions.

[00036] FIG. 1 illustrates a system 10 by which polarized imaging with a mobile device can be utilized in a transmission-based illumination scheme. In one embodiment, non-polarized monochromatic or white light 12 from a light source 14 is passed through a linear polarizer 16. Linearly polarized light 18 exits the initial polarizer 16 and is subsequently passed through a sample medium 20, such as a blood smear on a microscope slide or through a microfluidic chamber (e.g., see FIGS. 4A- 4D), as described below. Images of the sample medium 20 taken at different polarization states are utilized to determine a presence of molecules that rotate the plane of polarization of the polarized light 18 (e.g., hemozoin, a birefringent byproduct of malaria) and hence detect and characterize a disease. Light 22 exiting the sample medium 20 is passed through an analyzer 24. An intensity of an image acquired by a detector after passing through the second linear polarizer and collection optics for microscopic resolution is related to the angle of the polarizer 16 and analyzer 24 with respect to each other and changes in the light incurred from the sample medium 20 and can be used for diagnosis (i.e. malaria or no malaria and type).

After passing through the analyzer 24, light converges at an image plane 26. In some embodiments, the system 10 can further include a compensator 28 that is disposed between the sample medium 20 and the second polarizer 24. In some embodiments the polarizers can be circular or elliptical and/or multiple wavelength light sources could be used to obtain enhanced contrast.

[00037] Referring generally to FIGS. 2A-2C, multiple views of a mobile- imaging device 100 are shown. The mobile-imaging device 100 comprises a mobile device 102, a mount 104, and a sampling module 106. Different sampling modules may be used to conduct different kinds of analysis, such as, for example, transmissive-polarization imaging and reflective-polarization imaging. A sampling module 106 for transmissive-polarization imaging is shown in FIGS. 2A-2C. The sampling module 106 may be useful, for example, for detection of malaria. A sampling module 206 for reflective-polarization imaging is shown in FIGS. 3A-3C. The sampling module 206 may be useful, for example, for detection of skin cancer.

[00038] The mobile device 102 may be any of numerous commercially available mobile devices that include a camera. The mount 104 may comprise one or more mobile-device grips 108, one or more mobile-device grips 109, and a macro lens

110. The mobile-device grips 108 and 109 are adapted to secure the mobile device 102 to the mount 104. As shown in FIGS. 2A-2C, a pair of mobile-device grips 108 are provided to grip opposite sides of the mobile device 102 and a pair of mobile- device grips 109 are provided to grip a top edge and a bottom edge of the mobile device 102. In some embodiments the mobile-device grips 108 and 109 may be custom formed to grip a particular mobile device 102. In some embodiments, the mobile-device grips may be adjustable to accommodate more than one particular mobile device. For example, a distance between (e.g., a length or width) mobile- device grips 108 and 109 can be adjustable to accommodate a variety of mobile devices 102. In some embodiments, each mobile-device grip 108 and 109 can be adjusted independently to ensure that the camera of the mobile device 102 is appropriately aligned with the macro lens 110.

[00039] The mount 104 may include various cutouts and adaptations to allow access to various features of the mobile device 102. For example, the mobile-device grips 108 may include a cutout, such as, for example, a cutout 112 to permit access to one or more buttons or ports disposed on a side of the mobile device 102. The mobile- device grips 109 may also include a cutout, such as, for example, a cutout 114 to allow access to one or more buttons or ports disposed on a top or bottom edge of the mobile device 102.

[00040] The sampling module 106 shown in FIGS. 2A-2C is adapted for transmissive-polarization imaging. The sampling module 106 comprises a housing 116. The housing 116 includes at least one light 118, a slide rack 120, a polarizer 122, a polarizer 123 and a power cable 124. In some embodiments, the sampling module 106 is secured to the mount 104 via an attachment feature 126. The attachment feature 126 permits different components to be attached to the mount 104. For example, the attachment feature 126 permits different sampling modules, including the sampling module 106, to be attached to the mount 104. The attachment feature 126 can comprise different types of attachment mechanisms, such as, for example, one or more rails, snaps, hook and loop fasteners, and the like. The attachment feature 126 further includes an optical path 128 that permits light to pass between the sampling module 106 and the mobile device 102. The optical path 128 is aligned with the camera of the mobile device 102 and an opening in the housing 116 that provides a line of sight with the slide rack 120. A distance L between the slide rack 126 and the camera of the mobile device 102 defines a focal length of the mobile-imaging device 100. The attachment feature 126 further comprises an analyzer 130 disposed between the macro lens 110 and the slide rack 120. For analyzing blood smears in the detection of malaria in addition to histological stained slides, it is ideal to have the capability to transmit polarized-white light through the sample slide and then collect images with the analyzer oriented at a different polarization state or states such as at two or more angles, for example, both 45 degrees and 90 degrees with respect to the initial light source polarization. [00041] An optical path for transmissive imaging using the mobile-imaging device 102 will now be described. The optical path begins with the at least one light 118. The at least one light 118 may comprise one or more white LEDs. The at least one light 118 provides light to a sample medium (e.g., the sample medium 20). Other light types may be used in various other embodiments. Power for the at least one light 118 may be supplied by the mobile device 102 through the power cable 124. The power cable may plug into a port of the mobile device 102 (e.g., a USB or headphone port). In some embodiments, power for the at least one light 118 may come from a source other than the mobile device 102, such as, for example, a battery pack, an external power supply, and the like. [00042] Light from the at least one light 118 then passes through the polarizer

122, which is placed in the optical train to generate a polarized state such as circular or linearly polarized light prior to transmission through the sample medium 20. Light then travels to the slide rack 120 where the sample medium 20 (e.g., a blood smear or histological slide) is inserted into the optical path. The slide rack 120 is located such that the sample medium 20 is optimally positioned at the focal length L of the camera of the mobile device 102. In one embodiment of the mobile-imaging device 100, the entire sample FOV can be scanned via an electronically automated and deformable mirror chip that allows for the light to be steered into specific locations that is then individually collected via the mobile-imaging device 100. This allows for the option of a mosaic image of the entire sample or an individual image of a specific region within the sample yielding both good resolution and field-of-view. Following the slide rack 120, light then passes through the polarizer 123, which is oriented at one or more angles such as 45° with respect to the incident polarized light 118. The polarizer 123 is movable into and out of the optical path. Following the polarizer 123, positioned a distance relative to the focal length of the lens combination utilized in the setup, is a lens combination providing magnification of the image of the sample medium reaching the camera of the mobile device 102.

[00043] In some embodiments of the mobile-imaging device 100, rather than an adjustable deformable mirror, a multi -position slide insert can be manually moved past the camera of the mobile device 102 from left to right in incremental steps. These incremental movements through the sample also allow for the option of a mosaic image of the entire sample or an individual image of a specific region within the sample. In some embodiments the polarizer and analyzer 122 and 123 can be circular or elliptical polarizers. In some embodiments the polarizers 122 and 123 can be rotated to any angle.

[00044] In some embodiments of the mobile-imaging device 100, on-chip holography can be applied to improve the FOV and reduce the number of required optical components. In this configuration the sample (e.g., the microscope slide or the automated microfluidic chamber) is placed between two polarizers. One polarizer is placed between the mobile device 102 and slide rack 120, and a second polarizer is placed after the sample medium 20 is followed by a light source allowing for transmitted polarized light to traverse the sample medium 20.

[00045] Referring now to FIGS. 3A-3C, a reflectance-based mobile-imaging device 200 for utilizing polarized imaging in the diagnosis of skin cancer types is shown. The mobile-imaging device 200 comprises a mobile device 202, a mount 204, and a sampling module 206. The mobile device 202 and mount 204 are similar to the mobile device 102 and the mount 104 discussed above relative to the mobile-imaging device 100. The mobile device 202 may be any of numerous commercially available mobile devices that include a camera. The mount 204 may comprise one or more mobile-device grips 208, one or more mobile-device grips 209, and a macro lens 210. The mobile-device grips 208 and 209 are adapted to secure the mobile device 202 to the mount 204. As shown in FIGS. 3A-3C, a pair of mobile-device grips 208 are provided to grip opposite sides of the mobile device 202 and a pair of mobile-device grips 209 are provided to grip a top edge and a bottom edge of the mobile device 202. In some embodiments the mobile-device grips 208 and 209 may be custom formed to grip a particular mobile device 202. In some embodiments, the mobile-device grips may be adjustable to accommodate more than one particular mobile device. For example, a distance between (e.g., a length or width) mobile-device grips 208 and 209 can be adjustable to accommodate a variety of mobile devices 202. In some embodiments, each mobile-device grip 208 and 209 can be adjusted independently to ensure that the camera of the mobile device 202 is appropriately aligned with the macro lens 210.

[00046] The mount 204 may include various cutouts and adaptations to allow access to various features of the mobile device 202. For example, the mobile-device grips 208 may include a cutout, such as, for example, a cutout 212 to permit access to one or more buttons or ports disposed on a side of the mobile device 202. The mobile- device grips 209 may also include a cutout, such as, for example, a cutout 214 to allow access to one or more buttons or ports disposed on a top or bottom edge of the mobile device 202.

[00047] The sampling module 206 is configured for reflectance mode polarized imaging and comprises at least one light 218 to provide reflective illumination of an area to be imaged. The sampling module 206 is secured to the mount 204 via an attachment point 226. The attachment point 226 is similar to the attachment point 126. The sampling module 206 is adapted to set a focal length L to be located at a subject's skin. A polarizer 222, which may be a polarizer sheet, is placed in the optical train such that the polarizer 222 covers the at least one light 218 but contains an open center portion that allows reflected light to pass through the macro lens 210 and eventually the camera of the mobile device 202. In some embodiments the at least one light 218 is patterned at a 25° angle off axis with respect to a light-collection path. In some embodiments, multiple lights 218 may be disposed around a circumference of the macro lens 210. A second polarizer 223 that is oriented at the same angle with respect to the light source is placed into the optical path. In some embodiments, the polarizer 223 is movable into and out of the optical path. Following this component, positioned a distance relative to the focal length, is a lens combination as described above. The final component prior to the mobile device is a polarizer 224. The polarizer 224 may be a polarizer sheet that is oriented 90 degrees with respect to the polarizer 222 and is placed just prior to the camera of the mobile device 202. Utilizing the mobile-imaging device 200, a series of images can be acquired with the intensity setup in perpendicular polarized mode and parallel polarized mode for image analysis and margin enhancement for improved diagnosis of potentially cancerous areas.

[00048] The mobile-imaging devices 100 and 200 may be constructed in various ways. For example, the mobile-imaging devices 100 and 200 may be constructed using 3D printing technologies. The mobile-imaging devices 100 and 200 can be made for a relatively low cost compared to traditional imaging equipment. The mobile-imaging devices 100 and 200 provide a high quality, noninvasive, mobile- device-based optical polarimetric imaging system for point-of-care applications. Utilizing a single lens on-chip white light polarized imaging setup, the mobile- imaging devices 100 and 200 can aid in in the diagnosis of several diseases through the detection of variations in the states of polarized light as it passes through tissue or blood sample.

[00049] Referring generally to FIGS. 4A-4D, diagrams of microfluidic sample- chamber configurations for use with the mobile-imaging device 100 are shown. FIG. 4A shows a side view (a) and a top view (b) of a microfluidic microscopic blood-slide configuration 400. The configuration 400 comprises a housing 405. The housing 405 is adapted to accept a blood sample for analysis by the mobile-imaging device 100 and comprises a stain reservoir 406, a detection reservoir 407, and a waste reservoir 408. The detection reservoir 407 is in fluid communication with the stain reservoir 406 and the waste reservoir 408 via lines 410 and 412, respectively. The detection reservoir 407 comprises a narrow channel that allows a blood sample 414 to be dispersed via capillary motion for imaging. The blood sample 414 is injected via a standard gauge needle into the detection reservoir 407 through an input port 416. The input port 416 is fluidly coupled to the detection reservoir via a line 418. The blood sample 414 may be optionally covered in a biological staining agent that is stored in the stain reservoir 406 to allow for optimized viewing of many characteristics within the blood sample 414. Release of the staining agent is controlled by a valve 420.

[00050] The configuration 400 may also comprise a blood-smear actuator 422 that when either pressed or a small voltage is applied opens to release a component of the smear process into a combined well for mixing with and preparing the sample medium.

[00051] A vacuum pump 424 is adapted to remove air from the waste reservoir 408. The vacuum pump 424 may be, for example, a plunger-type pump that may be pressed one or more times to remove air from the waste reservoir 408. A valve 426 is coupled to the line 412 to modulate pressure between the waste reservoir 408 and the detection reservoir 407. For example, when the waste reservoir 408 is in vacuum relative to the detection reservoir 407, opening the valve reduces pressure within the detection reservoir 407 and draws some of the blood sample 414 into the waste reservoir 408. This helps pull the blood sample 414 though the detection reservoir 407 and also allows overflow or excess blood of the blood sample 414 to be removed from the detection reservoir 407.

[00052] FIG. 4B shows a side view (a) and a top view (b) of a microfluidic microscopic blood-slide configuration 401. The configuration 401 is similar to the configuration 400, except that the input port 416 has been replaced with in an input port 417. In contrast to the input port 416, which is sealed, the input port 417 is open.

The open input port 417 permits the drop of blood 414 to enter the input port 417 from a pipette or pricked finger for analysis in the detection reservoir 407. To draw the drop of blood 414 into the detection reservoir 407, capillary action can be used. Optionally, the vacuum pump 424 can be actuated to pull the blood drop through the detection reservoir 407. The blood drop 414 can optionally be covered with the biological staining agent from the stain reservoir 406 to allow for optimized viewing capability of many characteristics within the sample. [00053] FIG. 4C shows a side view (a) and a top view (b) of a vacuum- sealed microfluidic microscopic blood-slide configuration 402. The configuration 402 is similar to the configuration 400, except that the vacuum pump 424 has been removed and a relative vacuum is established in a waste reservoir 409. The relative vacuum is established in the waste reservoir 409 prior to using the configuration 402. Once a needle penetrates the port 416, a seal to the configuration 402 is no longer present and the relative vacuum of the waste reservoir 409 pulls the blood drop/sample 414 through the detection reservoir 407.

[00054] FIG. 4D shows a side view (a) and a top view (b) of a vacuum-sealed microfluidic microscopic blood-slide configuration 403. The configuration 403 comprises a housing 430 that further comprises a thin-blood- smear detection reservoir 432, a thick-blood-smear detection reservoir 434, and a waste reservoir 436. The detection reservoirs 432 and 434 allow for both thick and thin blood smears to be prepared at the same time in a single configuration 403. The thin and thick blood smears can be generated utilizing a single input of blood into an input port 438. Blood that is injected into the input port 438 enters both of lines 440 and 442 and subsequently enters into the detection reservoirs 432 and 434, respectively.

[00055] The waste reservoir 409 is fluidly coupled to the detection reservoirs 432 and 434 via lines 444 and 446, respectively. Similar to the waste reservoir 409, a relative vacuum is established in the waste reservoir 436. Once a needle penetrates the port 436, a seal to the configuration 403 is no longer present and the blood sample is pulled through the detection reservoirs 432 and 434.

[00056] Similar to the configurations 400, 401, and 402, the configuration 403 may comprise one or more valves to control a flow of the blood sample through the configuration 403. For example, valves 448 and 450 are adapted to control a flow of the blood sample through the lines 440 and 442, respectively, and a valve 448 is adapted to control a flow of the blood sample through the lines 444 and 446.

[00057] It will be recognized by a person of ordinary skill in the art that one or more of the features of the configurations 400, 401, 402, and 403 may be mixed and matched. For example, and not be way of limitation, the vacuum pump 424 of configurations 400 and 401 could be added to either of configurations 402 or 403. Similarly, the vacuum pump 424 of configurations 400 and 401 could be removed and the waste reservoir 409 of configuration 402 could be added.

[00058] For the proposed design to properly function in applications such as malaria detection and skin cancer detection, it is required that the device be capable of providing polarized light illumination onto the sample via a transmission and reflectance mode configurations. In the claimed design, an APP of the mobile device 102 or 202 is used to improve the repeatability, reliability, simplicity, and time required in image analysis for each condition (e.g., malaria or skin cancer). The APP is designed to simplify the process of pre-screening and improve the user experience through optimized settings for the mobile-imaging systems 100 and 200.

[00059] For skin cancer analysis, a polarized imaging setup is required that allows for polarized light to be reflected off the skin surface off axis from the path of the detection optics in the system. The mobile-imaging device 200 is capable of acquiring different polarization states such as left and right circular light or parallel and perpendicular polarized images of the sample. After the two images are acquired, the intensity of each image is utilized to generate an additional image which provides significantly greater information regarding the detail of the underlying structure on certain skin samples. Utilizing the APP, the two images are processed utilizing the Equation 1 below:

Eq. 1: lprocessed=(lpar-lper)/(lpar+lper)

[00060] Where lprocessed is the processed image intensity of each pixel within an image calculated as shown in Equation 1 above where, lpar is the image intensity of each pixel for a parallel configured optical path, and lper is the same image area intensity values of each individual pixel for a perpendicular configured optical path.

[00061] For malaria detection, (e.g., detecting the presence of birefringence through a blood sample) the system configuration is different than the setup described above for cancer. For the malaria embodiment, a blood smear can be placed on a microscope slide and inserted into the slide rack 120 of the mobile-imaging device 100 with the light source now configured to transmit the polarized light through the entire sample rather than reflected light as in the case for cancer. If malaria is present in the blood sample, the acquired image will have noticeable areas where the light passing through the sample varies in appearance across the blood smear. This is due to the fact that when the malaria parasite is present in the blood, it produces birefringent waste molecules as the parasite consumes hemoglobin. Thus, it is possible to infer the presence and severity of a malaria infection based on the amount of birefringent molecules present in the sample.

Experimental Examples

[00062] As a first step, a preliminary mobile-device-based imaging system comprises a conventional microscope objective and polarized tissue imaging system.

Two samples were imaged. A polarized image of a hair strand was acquired using a Nikon, infinity corrected, microscope objective (lOx magnification). The imaging system also used two polarizers in the setup one at the detector and another in front of the light source. From the image, the hair birefringence was clearly observed. However, in this setup, the focus and polarizers were not optimized to provide the best results. Another image of a back of a hand was collected. These images were used to verify the quality of the mobile camera available and to illustrate proof of principle.

[00063] An optical ray tracing simulation was performed to determine depth of focus, illumination beam path quality, and divergence angle of the mobile-imaging system. The effect these parameters had on the field-of-view, which is in focus for each design, was calculated. Additionally, the system magnification was calculated for each lens combination. Similarly, the numerical aperture of the system was measured and compared to the reported data. Using this number, the diffraction limited resolution was calculated for each setup configuration. Utilizing each variation of the hardware configurations and different lens combinations, images of an Air-Force-Target were acquired. In addition, various samples of biological and plant specimens were also imaged. In combination with the Air-Force-Target, a software package was used to determine the conversion of pixel length to distance in microns, which can be determined based on the known size of one of the rectangular bars on the Air-Force-Target. [00064] Using known camera settings and known image sizes, magnification, FOV, and resolution were calculated for a mobile-imaging device, such as, for example, the mobile-imaging device 100. Utilizing the Air-Force-Target, an axial resolution was calculated based on the full width at half maximum (FWHM) of the derivative of the line passing over the edge between a rectangle for three system configurations. An image of the Air-Force-Target was acquired utilizing the mobile- imaging device 100, with a single optical lens placed approximately 4 mm from a camera of the mobile device 102. Referring now to FIG. 5A, a graph showing the calculated Gaussian fit and derivative function for a line spread function placed halfway across Group #2, Element #4 of the Air-Force-Target is shown. The FWHM was calculated to be 3.78 microns for Element #2 in Group #4. Referring now to FIG. 5B, a graph showing the calculated Gaussian fit and derivative function for a line spread function placed halfway across Group #5, Element #1 of the Air-Force-Target is shown. The FWHM was calculated to be 2.49 microns for Element #1 in Group #5. The field of FOV was determined to be 4.04 mm x 3.03 mm in this configuration.

[00065] In another embodiment, the lens combination was switched with a macro lens configuration allowing for a wider FOV to be achieved. Using the macro lens, an image of a the standard Air-Force-Target was acquired utilizing a polarized imaging mobile device platform, such as, for example, the mobile-imaging device 100, with a single optical lens placed approximately 4 mm from the mobile device camera. FIG. 6 is a graph of the calculated Gaussian fit and derivative function for a line spread function placed halfway across Group #2 Element #1 of the standard Air- Force-Target. In this configuration, the FWHM was calculated to be 21.86 microns for Element #1 in Group #2 with a FOV calculated to be 5.04 mm x 6.72 mm.

[00066] In this patent application, reference to encoded software may encompass one or more applications, bytecode, one or more computer programs, one or more executables, one or more instructions, logic, machine code, one or more scripts, or source code, and vice versa, where appropriate, that have been stored or encoded in a computer-readable storage medium. In particular embodiments, encoded software includes one or more application programming interfaces (APIs) stored or encoded in a computer-readable storage medium. Particular embodiments may use any suitable encoded software written or otherwise expressed in any suitable programming language or combination of programming languages stored or encoded in any suitable type or number of computer-readable storage media. In particular embodiments, encoded software may be expressed as source code or object code. In particular embodiments, encoded software is expressed in a higher-level programming language, such as, for example, C, Python, Java, or a suitable extension thereof. In particular embodiments, encoded software is expressed in a lower-level programming language, such as assembly language (or machine code). In particular embodiments, encoded software is expressed in JAVA. In particular embodiments, encoded software is expressed in Hyper Text Markup Language (HTML), Extensible Markup Language (XML), or other suitable markup language.

[00067] Depending on the embodiment, certain acts, events, or functions of any of the algorithms described herein can be performed in a different sequence, can be added, merged, or left out altogether (e.g., not all described acts or events are necessary for the practice of the algorithms). Moreover, in certain embodiments, acts or events can be performed concurrently, e.g., through multi-threaded processing, interrupt processing, or multiple processors or processor cores or on other parallel architectures, rather than sequentially. Although certain computer-implemented tasks are described as being performed by a particular entity, other embodiments are possible in which these tasks are performed by a different entity. [00068] Conditional language used herein, such as, among others, "can,"

"might," "may," "e.g.," and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or states. Thus, such conditional language is not generally intended to imply that features, elements and/or states are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without author input or prompting, whether these features, elements and/or states are included or are to be performed in any particular embodiment.

[00069] While the above detailed description has shown, described, and pointed out novel features as applied to various embodiments, it will be understood that various omissions, substitutions, and changes in the form and details of the devices or algorithms illustrated can be made without departing from the spirit of the disclosure. As will be recognized, the processes described herein can be embodied within a form that does not provide all of the features and benefits set forth herein, as some features can be used or practiced separately from others. The scope of protection is defined by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

CLAIMS What is claimed is:

1. A mobile-imaging system comprising: a mobile-device mount adapted to secure a mobile device; and a sampling module secured to the mobile-device mount and comprising a housing, wherein the housing comprises a light and a polarizer disposed between the light and the mobile-device mount.

2. The mobile-imaging system of claim 1, wherein the housing of the sampling module further comprises a slide rack adapted to receive a sample for imaging analysis.

3. The mobile-imaging system of claim 1, wherein the sampling module is secured to the mobile-device mount via an attachment feature, the attachment feature comprising an optical path formed through the attachment feature and aligned with a camera of the mobile device.

4. The mobile-imaging system of claim 1, further comprising a macro lens secured to the mobile-device mount and positioned to align with a camera of the mobile device that is attached to the mobile-device mount.

5. The mobile-imaging system of claim 1, wherein the sampling module further comprises a power cable that attaches to the mobile device to provide power to the sampling module.

6. The mobile-imaging system of claim 1, wherein the sampling module comprises: a slide rack disposed between the polarizer and a second polarizer; and an analyzer disposed between the second polarizer and the mobile-device mount.

7. The mobile-imaging system of claim 6, wherein the sample further comprises a translational stage that allows the light to be steered into specific locations of the sample to capture a larger image.

8. The mobile-imaging system of claim 6, wherein the sampling module further comprises an automated deformable mirror chip that allows light from the light to be steered into specific locations to capture a larger image of a sample.

9. The mobile-imaging system of claim 1, wherein the polarizer comprises a ring shape and is disposed to be between the light and a sample when performing an analysis of the sample, and wherein light that is reflected from the sample passes through an open portion of the ring- shaped polarizer.

10. The mobile-imaging system of claim 9, further comprising a second polarizer disposed across the open portion of the ring-shaped polarizer, and wherein the light is disposed between the polarizer and the second polarizer.

11. The mobile-imaging system of claim 10, further comprising a rotational stage for the second polarizer that allows for multiple polarization angles.

12. The mobile-imaging system of claim 10, further comprising a power cable that attaches to the mobile device to provide power to the sampling module.

13. The mobile-imaging system of claim 1 further comprising a microfluidic sample cartridge adapted to fit within the sampling module and comprising: a housing; a detection reservoir and a waste reservoir disposed within the housing and connected to one another via a first passageway; and an input port disposed on a surface of the housing and connected to the detection reservoir via a second passageway.

14. A microfluidic sample cartridge comprising: a housing; a detection reservoir and a waste reservoir disposed within the housing and connected to one another via a first passageway; and an input port disposed on a surface of the housing and connected to the detection reservoir via a second passageway.

15. The microfluidic sample cartridge of claim 14 further comprising a stain reservoir that contains a staining agent and is connected to the detection reservoir via a third passageway.

16. The microfluidic sample cartridge of claim 14, further comprising a valve adapted to modulate a flow of fluid between the waste reservoir and the detection reservoir.

17. The microfluidic sample cartridge of claim 14, further comprising a vacuum pump coupled to the waste reservoir for removing a fluid from the waste reservoir.

18. The microfluidic sample cartridge of claim 14, further comprising a second detection reservoir that is coupled with the input port and the waste reservoir.

19. A method of analyzing a sample with a mobile-imaging device, the method comprising: placing a mobile-imaging device in proximity to a sample, the mobile imaging device comprising: a mobile-device mount adapted to secure a mobile device; and a sampling module secured to the mobile-device mount and comprising a housing, wherein the housing comprises a light and further comprises a polarizer disposed between the light and the mobile-device mount; directing a beam of light from the light through the polarizer and onto the sample; and capturing an image of the sample with a mobile device that is attached to the mobile- imaging device.

20. The method of claim 19, wherein the sample is a blood sample that is placed into a microfluidic sample chamber, the microfluidic sample cartridge comprising: a housing; a detection reservoir and a waste reservoir disposed within the housing and connected to one another via a first passageway; and an input port disposed on a surface of the housing and connected to the waste reservoir via a second passageway.

21. The method of claim 19, wherein the sample is a surface of a patient's skin.

22. The method of claim 19, further comprising analyzing the image using a mobile application on the mobile device.