WO2009011606A1

WO2009011606A1 - Apparatus for relaxation analysis in bathtubs

Info

Publication number: WO2009011606A1
Application number: PCT/RS2008/000019
Authority: WO
Inventors: Vladimir Randjelovic
Original assignee: Vladimir Randjelovic
Priority date: 2007-07-17
Filing date: 2008-06-12
Publication date: 2009-01-22
Also published as: EP2164395A1; RS51589B; RS20070308A

Abstract

Apparatus for relaxation analysis in bathtubs is designed to record exosomatic electrodermal activity and electrocardiographic signal over the electrodes placed on handgrips/rests of the bathtub or shower booth, connected in such way to allow single or multichannel recording. Besides, the device measures the temperature of the water, face and body of the user. The apparatus is equipped with underwater light system which is used to color the water in the bathtub according to the results of analyses of user's relaxation trend. In case that user is relaxing, the water is colored blue, while in the case of excitement, the water is colored red. While the user is neutral, the water is colored green. Different combinations of water colors are possible. The device further comprises processing unit connected to the audio system used to generate the sound used in stress control training and used to play back different musical playlists which support the process of relaxation in a bathtub. The apparatus communicates with the user over the keyboard and LCD, and also supports communication protocols used in connection with the PC or other devices.

Description

Apparatus for relaxation analysis in bathtubs

Technical Field

The present invention is related to electrodermal and electrocardiac activity measurement in a bathtub along with environmental and body temperature measurement. Additionally, the invention deals with underwater bathtub lighting. According to International Patent Classification, the invention could be classified as:

A61B 5/0402 (Bioelectricity measurement - electrocardiography), A61B 5/05 (Measurement with electric current and magnetic field), A61B 5/01 (Temperature measurement).

Background Art

Principal of exosomatic electrodermal response for detection of relaxation or excitement has been well documented in the literature, scientific articles and many patents. Prior art, however, does not include the system comprising the relaxation bathtub with temperature sensors and electrodes for electrodermal and electrocardiac activity recording, using which the apparatus determines the relaxation level of the user and activates the underwater light sources which color the water in the bathtub according to the relaxation level of the user.

Disclosure of Invention

Present invention represents a device used for measurement of exosomatic electrodermal activity (EDA), electrocardiographic activity (ECG) and temperature (T) of the user in a bathtub or shower booth. The aim of this measurement is determination of the psychological state of the user during the relaxation process in a bathtub. Based on determined psychological state, the apparatus activates different light sources that change the color of water according to the user's relaxation level. Using the sound generator (6, Fig. 1), communication system (5), the apparatus can activate different types of music to support the relaxation process.

The apparatus comprises the relaxation bathtub with electrodes and temperature sensors. Electrodes are connected with systems for EDA and ECG processing that are further connected to the microprocessor system where the EDA and ECG signals are sampled and processed. As shown on Fig. 1, the central part of the apparatus is the microprocessor system composed of processing unit (1), analog to digital (A/D) converter and memory (2). Most of the microcontrollers present on the market integrate all three components in the same integrated circuit. Therefore, because of space saving it is convenient to use the integrated version of the mentioned components. A/D converter should, in the case of multichannel sampling, be equipped with adequate number of analog inputs to allow multichannel sampling. Microprocessing system is connected with external memory reader/writer (R/W) used to read/write on external memory media such as flash memory cards (SD, MMC), CD, DVD, or similar, that could be used for user identification and recording of different software settings. This memory could also be used as data storage for different musical playlists activated in cases of different psychological states of the user. Microprocessor system controls all other systems of the apparatus that are explained further in the text.

The apparatus has two main versions of embodiment, first of which is used for EDA signal recording, while the second is used for EDA and ECG recording. In embodiment 1 (Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 13), signal from electrodes is processed within the EDA processing circuit and then sent to AfD converter. In embodiment 2 (Fig. 7, Fig. 8, Fig. 9) signals from electrodes are first selected on demultiplexers (31-33, Fig. 9) and then sent to either EDA or ECG processing circuit. Embodiment 2 of the invention makes possible simultaneous analyses of EDA and ECG signals over the same electrodes.

Electrodes (22-25, Fig. 1) are produced in different shapes but mainly in the shape of the handgrips or hand rests (18-21) in such way that on the insulating material, out of which the handgrips/rests are made, electrodes are created out of conductive material in a way to form one or more separate electrodes. In certain cases, handgrips/rests can completely be made out of conductive material and be incorporated into the bathtub body produced of insulating material. In this case (Fig. 6) each of the handgrips (20, 21) and hand rests (18, 19) represents one electrode.

Electrodes connected to the signal generator make the group of emission electrodes, while the electrodes that take signal from the user and conduct it to the EDA processing circuit or to demultiplexers represent reception electrodes.

Contact between skin and emission or reception electrodes can be accomplished over one electrode, over many electrodes at the same time, over the water, or as combination of all mentioned contact types.

In embodiment 1 which concerns recording of EDA without ECG (Fig. 1), each of the handgrips/rests contains a group of reception electrodes, each being connected to the EDA processing circuit (14-17). Reception electrodes (23, 25) from every handgrip/rest (18-21) are connected to the separate EDA processing circuit (14-17) after which, the signal is sent forward to the multichannel A/D converter (9). This concerns EDA recording over multiple channels (in this case four). Simpler version of embodiment 1 (Fig. 2) comprises one group of emission electrodes (22, 24) placed on every handgrip/rest (18-21), and only one group of reception electrodes (23, 25), and therefore only one EDA processing circuit (14). This concerns recording of EDA over only one channel.

Even simpler version of embodiment 1 (Fig. 3) can be accomplished in a way that the group of emission electrodes counts only one electrode (24, 53) on each of the handgrips/rests, and that there is only one group of reception electrodes on each of the handgrips/rests counting only one electrode (25, 54).

The simplest case of electrode connection (Fig. 4) concerns version in which one handgrip/rest is equipped with only one emission electrode, while the other handgrip/rest is equipped with one group of reception electrodes counting only one reception electrode. In order for recording to take effect, it is necessary that user gets in contact with one handgrip/rest with one hand, while with other hand the user must get in contact with another handgrip/rest. Underwater emission electrode (44, Fig. 11) is used to bring the signal from the signal

85 generator (8, Fig. 6) to the water and over the water to the user. In this case electrode (44) is placed somewhere at the bottom of the bathtub so that the electrode is always in contact with the water even when the water level in the bathtub is low. This electrode makes contact with water and conducts the signal from the signal generator (8), over water, to the user, hi that case, handgrips/rests (18-21) can be equipped with only one reception

90 electrode (23, 25, 45, 46), while water, being in contact with the user, represents the emission electrode.

Signal from reception electrodes, located on all handgrips/rests (18-21) can be connected to only one EDA processing circuit (14, Fig. 6) in which case it is possible to accomplish single channel recording, hi case of multichannel recording (Fig. 5), signal from reception 95 electrodes located on all handgrips/rests (18-21) is taken to separate EDA processing circuits (14-17), after which signal is sampled by the A/D converter (9).

In this case (Fig. 5), as in previous (Fig. 6), handgrips/rests can completely be produced out of conductive material if they are attached to the bathtub whose body is produced of insulating material since each of the handgrips/rests carries one electrode only.

100 Fig. 13 shows the way to connect six reception electrode groups, which take the signal to the separate EDA processing circuits (14, 15, 16, 17, 55, 56), after which, the signal is sampled by the A/D converter (9).

Fig. 13 shows two hand rests (18, 19) having one electrode each (23, 45), and two handgrips (20, 21) having one reception electrode each (25, 46). When handgrips/rests 105 contain one electrode only, they can be produced of conductive material.

Fig. 13 also shows two handgrips (59, 60), each equipped with many reception (58) and many emission (57) electrodes. In case when handgrips/rests contain more than one electrode, it is convenient to produce them out of insulating material with electrodes made of conductive material placed on the surface of handgrip/rest. Emission electrodes (57)

110 from both handgrips (59, 60) are mutually connected with conductor and are connected further with underwater emission electrode (44), as well as with signal generator (8). In other words, signal from the generator (8) is distributed over the underwater electrode (44) and water in the bathtub to the user's skin, providing thereby, on the skin of the user, the voltage level necessary for EDA recording which is further detected over the reception

115 electrodes. Emission electrodes from the handgrips (59, 60) distribute the voltage from the signal generator to the user only when user with any part of the body gets in contact with handgrips. On the other side, reception electrodes (23, 45, 25, 46, 58) detect EDA signal from the user whenever the user gets in contact with any of the handgrips/rests.

Embodiment 2 is concerned with simultaneous recording of EDA and ECG signals (Fig. 7, 120 Fig. 8). In this embodiment, electrodes are connected so that there is one group of emission electrodes and at least two groups of reception electrodes, while in this case, signal from every of the reception electrodes Wl (26), W2 (27), W3 (28), W4 (29) from handgrips/rests is taken to the signal selector (31-33, Fig. 9).

As opposed to embodiment 1, in which it is necessary to have one group of emission 125 electrodes and at least one group of reception electrodes, embodiment 2 requires the presence of one group of emission electrodes and at least two groups of reception electrodes. Two groups of reception electrodes are necessary to record the ECG signal which can only be recorded if the ECG processing circuit (30, Fig. 9) is in contact with the signal from the left hand and the signal from the right hand of the user at the same time. 130 Because of this, in embodiment 2 at least one group of reception electrodes must be placed on the handgrips/rests located on the left hand side of the user, while at least one group of reception electrodes must be placed on handgips/rests located on the right hand side of the user.

System for exosomatic electrodermal activity (EDA) recording consists of signal

135 generator (8, Fig. 6) and EDA processing circuit (14). Signal generator (8) is used to generate certain voltage level which is brought to the user, while EDA processing circuit detects the voltage from the user's hands, processes it and sends it to the A/D converter (9).

Principle of EDA recording is extensively explained in the prior art. It is based on the idea to bring certain voltage level to the user's skin over one electrode, and to record voltage

140 level on another skin location. This signal is then amplified and filtered. Essentially, this method measures the resistance of the user's skin and is known under the name GSR - galvanic skin resistance. Signal generator can produce constant voltage level, changeable

DC voltage, and alternating (AC) voltage of extremely small frequency. Each of these voltage sources can be used in the process of EDA recording. Frequently it is useful to

145 apply AC voltage of extremely small frequency in order to decline the polarization effects of electrodes. Signal generator (8) can be used to produce zero potential which may be used during ECG recording.

In embodiment 1 (Fig. 1) there are four EDA processing circuits (14-17). Each of these circuits is connected to one group of reception electrodes on handgrips/rests (18-21).

150 In embodiment 2 (Fig. 8, Fig. 9) one EDA processing circuit (14) is used to which the EDA signal is brought over the demultiplexer (33) which can select signals from each of the four groups of reception electrodes (W1-W4) (26-29) .

System for EDA signal processing operates continually and sends the EDA signal to the A/D converter. On the other side, processing unit activates the A/D conversion, reads the 155 result of the conversion and stores it into its memory only during the signal recording period which takes place during the certain time intervals (usually 10- 100ms). Processing unit software monitors the operation of A/D converter and, as soon as the conversion is completed, processing unit stores the digital value of the EDA voltage into its memory (2).

ECG processing circuit (30, Fig. 9) is available on the market in many different versions.

160 This circuit comprises ECG amplifier and filter used to filter the signal using the band pass filter between 5-40Hz. In case that more detailed characteristics of the ECG are required the band pass filter should be designed to operate between 0.05Hz and 150Hz in combination with notch filter operating at 50 or 60Hz depending on the power frequency. ECG signal filtered this way is sent further to the analog input of the A/D converter (9).

165 ECG processing circuit operates continually and sends the ECG signal to the A/D converter which is sampled in certain time intervals defined by the processing unit software (usually 1-lOms). Sampled ECG signal is stored in the memory and then processed within the processing unit in order to determine user's heart rate and other ECG characteristics.

170 ECG signal can be recorded only in embodiment 2 of the invention. In order for ECG recording to take place, the processing unit must first determine which of the electrode groups (W1-W4) are in contact with the user and, based on this analysis, select signals from demultiplexer (31, 32), so that the positive input of the ECG processing circuit (30) receives the signal from the right hand of the user, while the negative input receives the

175 signal from the left hand of the user. Electrode selection system (Fig. 8, Fig. 9) is used only in embodiment 2 of the invention. This system consists of three demultiplexers (31-33) which can be realized with electronic analog demultiplexers or signal selectors, analog switches, mechanical switches or relays.

Demultiplexer A (31) is used to select signal from one of the electrode groups (W1-W4) 180 and to conduct it to the positive input of the ECG processing circuit (30).

Demultiplexer B (32) is used to select signal from one of the electrode groups (W1-W4) and to conduct it to the negative input of the ECG processing circuit (30).

Demultiplexer C (33) is used to select signal from one of the electrode groups (W1-W4) and to conduct it to the EDA processing circuit (14).

185 Signal selection on demultiplexers is controlled by the processing unit. The role of demultiplexers is to allow the usage of the same electrodes for both EDA and ECG signal processing.

For ECG recording it is necessary to have the user connected, over the electrodes, in such way that at least one emission electrode from handgrips/rests be on zero potential, that 190 user's left hand is in contact with one of the reception electrode groups (W1-W2), while user's right hand is in contact with any of the groups (W3-W4) of reception electrodes. Fig. 9 shows an example where four groups of electrodes are placed on four different handgrips/rests. Greater number of electrode groups can be accomplished by greater number of handgrips/rests connected using the same principle.

195 Zero potential is brought to emission electrodes over the signal generator (8). Contact with zero potential is made as soon as the user touches the handgrip/rest, and with it, at least one of the emission electrodes.

In case of underwater emission electrode (44, Fig. 11), handgrips/rests (18-21, Fig. 8) can be equipped with only one reception electrode (23, 25, 45, 46), using which signal is

200 conducted over the leads W1-W4 (26-29) to the signal selection system (Fig. 9). In this case zero potential is, over the signal generator (8), conducted to the underwater electrode (44) which, being in contact with the water, distributes the zero potential, through the water, to the user. Principle of ECG signal recording is based on the idea to distribute the zero potential to the user, through water, to make the contact between user's left hand and

205 leads Wl or W2, and to make the contact between user's right hand and leads W3 or W4. In this case the ECG is recorded using the standard lead 1 configuration.

In the beginning, processor sends the command to the signal generator to activate certain voltage level used for EDA recording. On the other hand, processor successively selects signals from the electrode groups W1-W4 over selector (33) which further takes the signal 210 to the EDA processing circuit (14). This circuit sends the processed EDA signal to the A/D converter which samples it and sends it in a digital form to the processing unit. This way, processor scans the leads W1-W4 in order to detect EDA activity in any of the leads Wl- W4. EDA activity will be detected only on those electrodes which are in contact with the user's skin.

215 In case that user holds hands on the electrode groups W2 and W4, the apparatus will, during successive selection of EDA channels (scanning), detect EDA activity only in channels C2, C4 of the selector (33). In that case, processor starts recording of ECG signal by switching the selector (31) to A2 channel, and selector (32) to B4 channel. Processor, further, sends command to the signal generator to activate the zero potential. This way, the

220 circuit for ECG signal processing (30) receives signals from electrode groups W2 and W4, that is potentials of user's left and right hand. This is the standard lead 1 configuration in ECG recording.

System for water lighting is designed to color the water with regard to user's trend of relaxation. While user is in the relaxation trend, the water is colored blue. In case of that 225 trend is neutral, the water is colored green, and in case the user is in the excitement trend, the water is colored yellow or red. When user is not in contact with electrodes, the water is either colored white or the lights are switched off.

Lighting system is equipped with several light sources (11, 49, 52) of different color. Fig. 1 shows three light sources while its number could be even greater. Every new light source 230 attached to the system is connected using the same principle as light sources (11, 49, 52).

System consists of digital to analog (D/A) converter (37, 47, 50), over which the processing unit (1) adjusts the light intensity, amplifiers (10, 48, 51) whose role is to provide proper voltage and current levels for the light sources (11, 49, 52) which could emit blue (B), green (G), red (R) or any other light color.

235 Water lighting systems are explained in the prior art and are widely available on the market. Light sources must be produced in water proof cases to make the underwater usage possible.

Audio system comprises the sound generator (6) including the stereo sound decoder and amplifier connected to the processing unit (1), speakers or headphones (7). In this system,

240 processing unit, over the sound generator (6), which includes the D/A converter, generates sound waves of certain frequency which correlate with the level of user's excitement. The higher the excitement, the higher the frequency of the sound. This way, the user can train the control of relaxation or excitement. Besides, audio system could be used to playback the sound chosen by the user which could supports the processes of either relaxation or

245 excitement. Playback music could be stored in the digital form within the memory (2) or external memory (43).

System for temperature measurement of the user comprises the infrared temperature sensor T_1R (13) and classical conductive temperature sensors Tl (12).

Temperature sensor T_1R measures the temperature by measuring the intensity of the 250 infrared light that is emitted from the body. This type of sensor is explained in the literature and is widely available on the market. In the present invention, this type of sensor could be placed anywhere on the bathtub and be directed to the face and body of the user. Fig. 10 shows this sensor (13) mounted on the bathtub (34).

Large number of standard temperature sensors (Tl) can be placed on different locations

255 within the bathtub so that they measure the temperature on different locations. Fig. 1 shows the connection of this sensor (Tl), although several more sensors could be added to the system in order to measure the temperature on different bathtub locations. A number of these sensors allow direct connection to the processing unit since they are equipped with integrated A/D converter and system for communication with the processing unit. In case

260 of usage of sensors that do not support this kind of connection it would be necessary to connect them to the A/D converter.

User interface comprises the keyboard (3, Fig. 1) and display (4). Keyboard and display

(usually LCD) are connected directly to the processing unit (1). During the operation of the apparatus, processing unit checks the state of the keyboard and determines which of the

265 buttons is pressed. In case that button is pressed, the software of the processing unit decides about procedures that should be activated. LCD is also connected to the processing unit directly and is updated in certain time intervals.

Communication system (5) with other devices or systems is internally supported by the processing unit. The communication with other devices could be accomplished over the 270 USB, Ethernet, CAN, RS232, RS485, SPI or other types of communication. The communication system allows the connection of the presented apparatus with other devices such as PC, mobile phone, audio devices and similar.

USB communication can be accomplished by direct connection of the processing unit (1) with the USB port. SPI communication is accomplished in very short distances by direct 275 connection of the processing unit (1) with processing units of other devices. RS232, RS485, CAN and Ethernet communication require driver integrated circuits witch are, on one side, directly connected to the processing unit (1), while on the other side driver circuits are connected to the corresponding connector.

Besides mentioned communication protocols, communication system (5) supports wireless 280 connection that is accomplished with any RF integrated circuit connected directly to the processing unit (1) on one side, and to antenna on the other side. One of the RF solutions includes usage of Bluetooth integrated circuits which allows radio communication in short distances. In addition to radio communication, processing unit can also be connected to any of the available infrared communication circuits.

285 Present invention is designed to record exosomatic electrodermal activity, electrocardiographic activity and temperature of the user during the relaxation in a bathtub. Alteration in EDA activity occurs as a result of alteration of the activity of the autonomus nervous system of the user. The level of EDA activity rises as a result of a stressful event. Oppositely, during the relaxation or even drowsiness, the EDA level declines. ECG

290 activity and temperature are used as information that provides further evidence about the current psychological state of the user.

During the relaxation in a bathtub (hydro massage bathtub, shower booth or similar), software of the processing unit performs analyses of EDA, ECG and temperature signals and concludes about the user's relaxation/excitement trend. Based on this analysis, the 295 device undertakes certain actions which may be preprogrammed. The device can change the color of the water, showing to the user the actual trend of relaxation. By watching the water color, the user can learn how to relax or how to excite more efficiently. Bathtub could be equipped with water jets or air bubbles which could support the process of relaxation.

300 To present the relaxation trend based only on EDA activity, the apparatus uses the following procedure (Fig. 12). Using the previously described method, the apparatus reads (38) the EDA values from the user's body. Measured values of EDA are then analyzed (39). During this analysis, the apparatus determines whether the EDA values take the rising or falling trend. In case that the EDA trend is falling, meaning that the user is in relaxation,

305 the apparatus activates the blue light (40). In case that the EDA trend is neutral (neither falling nor rising), the apparatus activates the green light (41). In case of the rising EDA trend, the red light is activated (42).

The device can also be used for music selection that is played back over the audio system (6, 7). Also, the apparatus could send signal, over the communication system (5) to other 310 devices (other audio systems or PC) to activate certain musical playlists in accordance with the actual relaxation trend. Having in mind that electrodermal response could be recorded over multiple channels, over several different handgrips/rests, it is possible to bring conclusion about the position of the user's arms. This information could be useful in the estimation of the user's relaxation 315 trend.

Brief Description of Drawings

Fig. 1 is the schematic of the basic components of the apparatus in embodiment 1 and multichannel EDA recording.

Fig. 2 is the schematic of the basic components of the apparatus in embodiment 1 and 320 single channel EDA recording.

Fig. 3 shows the electrode connection in embodiment 1 and handgrips/rests with one emission and one reception electrode.

Fig. 4 shows the electrode connection in case that one handgrip contains one emission electrode, while the other handgrip contains one reception electrode.

325 Fig. 5 shows the electrode connection in case that underwater electrode is used as emission electrode, while reception electrodes are used as handgrips/rests each being connected to one EDA processing circuit (multichannel).

Fig. 6 shows the electrode connection in case that underwater electrode is used as emission electrode, while reception electrodes are used as handgrips/rests all of which are connected 330 to one EDA processing circuit (single channel).

Fig. 7 is the schematic of electrode connection in embodiment 2.

Fig. 8 is the schematic of electrode connection in embodiment 2, in case that the underwater electrode is used as emission electrode.

Fig. 9 is the schematic of basic elements in embodiment 2. 335 Fig. 10 shows the bathtub with electrodes and other elements of the system

Fig. 11 shows the bathtub with electrodes and other elements of the system in case that underwater electrode is used as emission electrode.

Fig. 12 describes the procedure for presentation of user's relaxation trend using different light colors.

340 Fig. 13 shows the connection of one underwater emission electrode, to handgrips with one reception electrode, two hand rests with one reception electrode and two handgrips with several emission and several reception electrodes.

Claims

1. Apparatus for relaxation analysis in bathtubs characterized by a bathtub equipped with electrodes organized in a way to create one group of emission electrodes and at least one group of reception electrodes using which the electrodermal and electrocardiographic signals are taken from the user, over the EDA processing circuit or ECG processing circuit to A/D converter where the said signals are sampled and forwarded to the processing unit, which by signal analyses, estimates the psychological state of the user, and according to that, activates light sources of different color using which the water in the bathtub is colored according to the psychological state of the user.

2. Apparatus according to claim 1 characterized by emission electrodes placed at the bottom or at side walls of the bathtub in order to make the electric contact with the water which further makes electrical contact with the user allowing this way the water to play the role of emission electrode.

3. Apparatus according to claim 1 characterized by emission and reception electrodes produced in the form of handgrips or hand rests.

4. Apparatus according to claim 1 characterized by emission and reception electrodes placed on handgrips or hand rests.

5. Apparatus according to claim 1 and embodiment 1 characterized by at least one of the reception electrode groups be connected to the EDA processing circuit which is further connected to the A/D converter that is in connection with the processing unit.

6. Apparatus according to claim 1 and embodiment 2 characterized by each of the reception group of electrodes being connected to signal demultiplexer which makes connection between each of the reception electrode groups and EDA processing circuit, which is further connected to the A/D converter that is in connection with the processing unit.

7. Apparatus according to claim 6 characterized by each of the reception group of electrodes being connected to the signal demultiplexer which takes the signal from every of the reception electrode groups and connects it with the negative input of the ECG processing circuit, which is further connected to the A/D converter that is in connection with the processing unit.

8. Apparatus according to claim 6 characterized by each of the reception group of electrodes being connected to the signal demultiplexer which takes the signal from every of the reception electrode groups and connects it with the positive input of the ECG processing circuit, which is further connected to the A/D converter that is in connection with the processing unit.

9. Apparatus according to claim 1 characterized by the signal generator that is, on one side connected to the group of emission electrodes, while on the other side it is connected with the processing unit which controls its operation.

10. Apparatus according to claim 1 characterized by infrared temperature sensor that is connected to the processing unit.

11. Apparatus according to claim 1 characterized by one or more temperature sensors connected to the processing unit.

12. Apparatus according to claim 1 characterized by underwater lighting system that consists of light sources of different colors that are activated by the processing unit over the D/A converter and amplifier, allowing this way generation of different light colors with different intensities.

13. Apparatus according to claim 1 characterized by the audio system that consists of stereo audio decoder that generates the sound signal over its D/A converter and sends it to speakers or headphones over the amplifier circuit.

14. Apparatus according to claim 1 characterized by keyboard and display connected to the processing unit and used as user interface.

15. Apparatus according to claim 1 characterized by memory connected to the processing unit.

16. Apparatus according to claim 1 characterized by the means for external memory reading and writing where the said external memory is carried by the user for the purposes of user identification and memorizing of options offered by the software of the apparatus.

17. Apparatus according to claim 1 characterized by system for communication with other devices and personal computer over the wired, radio or infrared connection.

18. Procedure for presentation of the level of relaxation in a bathtub characterized by activation of different light sources according to the determined trend of EDA activity.

19. Procedure according to claim 18, characterized by activation of light sources that color the water in a bathtub with red tones of color in case that EDA has a rising trend, that neutral trend of EDA activity activates the green light sources, while the fall in EDA trend activates the light sources of blue tones of color.

20. Procedure for ECG and EDA recording from the electrodes placed on the bathtub, characterized by identification of electrode groups that are in contact with user's hands through the process of EDA activity scanning over different electrode groups, and by recording of the ECG signal only from those electrode groups on which the contact with the user's skin was detected.