Device for continuously measuring the local skin-sweating rate

Abstract: A device for continuously measuring the local skin sweating rate includes a sensor (1) used for applying to human skin at a measuring point and an air supply element (10) for supplying dehumidified air to the sensor (1). A first chamber (3) is formed between the sensor and the skin for mixing water vapor perspired from the skin and the dehumidified air supplied from the air supply element. A second chamber (6) is also formed within the sensor (1) and connected with the first chamber (3) through a communicating hole (31). The device further includes a humidity detector (4) in the second chamber. The humidity detector (4) varies its capacitance according to the relative humidity of the mixture. A temperature detecting element (5) is disposed in the second chamber for detecting the temperature in the second chamber and for outputing signals corresponding to the temperature. A humidity detector output element (7) is mounted on the sensor (1) and is electrically connected with the humidity detector (4) for outputing a humidity signal. A processor (18) calculates the sweating rate, which is independent of the temperature of the mixture, based on the humidity and temperature signals. An element is provided for continuously recording the data of the sweating rate obtained from the processor.

Description: The present invention relates to a device for continuously measuring the skin local sweating rate including rate of emotional perspiration as well as that of heat-sensitive perspiration. The devices for continuously measuring the skin local sweating rate are useful for a quantitive test of function of autonomic nervous system of a human body or sweating system for regulating body temperature, etc. Such devices are disclosed in Japanese Laid-Open Patent Publications Nos 63-46131 and also 63-57031 on which the precharacterising portion of claim 1 is based. Japanese Laid-Open Patent Publication No 63-46131 discloses a measuring device comprising a capsule and an air supply device. The capsule is applied on a skin at a sweating rate measuring point to form a chamber between the capsule and the skin. Air is supplied into the chamber from the air supply device, and the difference of the humidity of the air supplied into the chamber and discharged from the chamber is detected. The sweating rate at the measuring point is calculated based on the difference of the humidity thus detected. Japanese Laid-Open Patent Publication No 63-57031 discloses a system comprising a dehumidifying device between a capsule and an air supply device. In this system, only one humidity sensor is required. The prior art sweat measuring devices detect the relative humidity in the capsule, and the sweating rate is calculated on the assumption that the temperature of the capsule is invariable. However, the inventors of the present invention have proved that the influence of the variation in the capsule temperature cannot be neglected to obtain reliable sweating rate. Further, in these prior art devices, oscillators are fixed on the rear surfaces of the capsules and include the humidity detecting sensors as a circuit component, so that the frequency of the oscillators is varied according to not only the relative humidity but also to the temperature of the capsule and the temperature of the atmosphere. Therefore, accurate sweating rates could not be measured. It is, accordingly, an object of the present invention to provide a device for continuously measuring the skin local sweating rate which can measure the sweating rate in such a manner that the sweating rate is independent of the temperature. It is another object of the present invention to provide a device for continuously measuring the skin local sweating rate which can compensate variations in the output of a humidity detecting means caused by variations in temperature of its electric circuit. According to the present invention, there is provided a device for continuously measuring the skin local sweating rate comprising: a capsule for application to the skin at a measuring point; air supply means for supplying dehumidified air to said capsule; a first chamber formed between said capsule and the skin for receiving water vapour perspired from the skin and the dehumidified air supplied from said air supply means to produce a mixture of the said water vapour and the dehumidified air; humidity detecting means varying its electrical circuit characteristic according to the relative humidity of the mixture; humidity detecting signal output means mounted on said capsule and electrically connected with said humidity detecting means for outputting a detected humidity signal corresponding to the circuit characteristic of said humidity detecting means; calculation means for calculating the sweating rate from the signals from said humidity detecting signal output means; and recording means for continuously recording the data of the sweating rate obtained by said calculation means; characterised by: temperature detecting means for detecting the temperature of the mixture and for outputting signals corresponding to the temperature; temperature compensation signal output means disposed in the vicinity of said humidity detecting signal output means and having the same electrical construction and the same temperature characteristic as said humidity detecting signal output means, said temperature compensation signal output means outputting a temperature compensation signal substantially corresponding to the temperature of said humidity detecting signal output means, said temperature compensation signal being supplied to said calculation means so as to compensate said humidity detecting signal; a second chamber formed within said capsule and connected with said first chamber through a communicating hole for allowing the mixture to flow from said first chamber into said second chamber and wherein the humidity and temperature detecting means are disposed to detect the humidity and temperature of the mixture in the second chamber, and in that said calculation means is adapted to calculate the sweating rate which is corrected in dependence on the temperature of the mixture based on the signal from said temperature detecting means. In the present invention thus constructed, the water vapour perspired from the skin is uniformly diffused and mixed with the dehumidified air supplied from the air supply means in the first chamber of the capsule. The water contents in the mixture and its temperature is detected by the humidity detecting means and the temperature detecting means, respectively. The calculation means calculate the sweating rate which is independent of the temperature, based on the signals from the humidity detecting signal output means and the temperature detecting means. Thus the calculation means correct the relative humidity obtained from the humidity detecting signal output means to the real humidity, or the temperature dependence of the signal from the humidity detecting signal output means is eliminated. Therefore, the continuous measurement of the sweating rate can be made easily and highly precisely. The device also includes temperature compensation signal output means disposed in the vicinity of the humidity detecting signal output means and having the same electrical construction and the same temperature characteristic as the humidity detecting signal output means. The temperature compensation signal output means outputs a temperature compensation signal substantially corresponding to the temperature of the humidity detecting signal output means. The temperature compensation signal is supplied to the calculation means so as to compensate the humidity detecting signal. Thus, the calculation means compensate the temperature drift of the humidity detecting signal output means, and provide more accurate sweating rate. A microprocessor can be employed as a main part of the calculation means so as to correct the relative humidity through its software and to display the sweating rate with a format to suit the purpose and to connect with an external general purpose computer. The systematisation and the extension of the system can be made by employing the microprocessor. Further, the invention may be embodied in a portable-type device comprising the capsule, air supply means, a first and second chamber, humidity detecting means, temperature detecting means, humidity detecting signal output means, the air supply means being in a portable box, and the device also having portable record means for continuously recording information concerning a function of a human body on detachable recording media for a long time, e.g. over extended periods, so that the humidity detecting signal and the temperature compensation signal can be recorded on the portable record means. The device of this portable-type may be used with a base station, comprising: regeneration means for regenerating and demodulating the signals recorded on the detachable recording media; the calculation means for calculating the sweating rate which is independent of the temperature of the mixture from the signals demodulated by the regeneration means; and the means for continuously recording the data of the sweating rate obtained by said calculation means and which may display the data. Thus, the system of this type can be generally divided into two sections, one of which is sweat measuring and recording section and the other of which is regeneration and displaying section. The sweat measuring and recording section may constitute a portable section. For this purpose, the air supply means disposed in the portable box may include a compressor of relatively small size so as to save energy. The portable box may include therein the electric circuit for processing the output signals from the humidity detecting means and the temperature detecting means disposed within the capsule. For recording the relative humidity and the temperature, an existing recording means such as a Holter's electrocardiograph which permits recording for a long time is available. The recorded data is regenerated by the regeneration means and may be processed by the calculation means such as a microprocessor. Thus, the system of this type permits daily continuous measurement of the sweating rate without rendering restriction to the subject. In the case that the Holter's electrocardiograph has been used as a recording means, the electrocardiogram can also be recorded simultaneously with the above data. Further, in this case, an approach to diagnosis of the cardiac function can be made using the sweating rate as a barometer by displaying the cardiogram together with the sweating rate. The device of the present invention can be used in the field of clinical medicine and sport medicine for testing the function of the autonomic nervous system of human body or the function of regulation of temperature. The device can also be used in the field of subsistence stores for testing the influence of vaporisation of water on a cosmetic etc or the migration of water in clothing. Particularly in the clinical application, the device can be used for the evaluation of the effect of medicines, or for judgment of the effect of the rehabilitation remedy. Thus, the invention can provide a device for continuously measuring the skin local sweating rate which can be used by a subject for daily measurement without rendering inconvenience or restriction and which can utilise an existing means such as a Holter's electrocardiograph as an instrument for recording the measured data. The invention will become more fully apparent from the claims and the description of preferred embodiments, described in connection with the drawings, in which:- Figure 1 is a block diagram showing a device for continuously measuring the skin local sweating rate according to a first embodiment of the present invention; Figure 2 is a diagram showing the digital calculating circuit of the device shown in Figure 1; Figure 3 is an enlarged sectional view of the capsule shown in Figure 1; FIG. 4 is a block diagram showing a device for continuously measuring the skin local sweating rate according to a second embodiment of the present invention; and FIG. 5 is a diagram showing several circuits incorporated in the portable box shown in FIG. 4. Referring to FIGS. 1 to 3, there is shown a device for continuously measuring the skin local sweating rate according to a first embodiment of the present invention. As shown in FIGS. 1 and 3, a capsule 1 is applied on a human skin 2 at a measuring point, and a first chamber 3 is formed between the capsule 1 and the skin 2. Within the capsule 1, a second chamber 6 is formed next to the first chamber 3, and both chambers 3 and 6 are communicated through a communication hole 31. The first chamber 3 produces a diffused mixture of perspiration oriented water vapor and a dehumidified air. The second chamber 6 includes therein a humidity sensor 4 and a temperature sensor 5. The humidity sensor 4 is electrically connected with a first oscillator 7. The first chamber 3, the humidity sensor 4, the temperature sensor 5, the second chamber 6 and the first oscillator 7 form a detecting section for detecting the sweating rate and the temperature. A second oscillator 8 is disposed on the same substrate as the first oscillator 7 and forms a temperature compensation section for the first oscillator 7. An air supply section for supplying the dehumidified air is formed by an air channel 9, a dehumidifying device 10 having silica gel and a compressor 11 therein. A processing section of a detected signal of sweating rate is formed by a first F/V converter 12 and a first amplifier 13 connected with the first oscillator 7. A temperature measuring section of the diffused mixture is formed by a second amplifier 14. An output section of a temperature compensation signal is formed by a second F/V converter 15 and a third amplifier 16 connected with the second oscillator 8. The other circuits subsequent to a differential amplifier 17 form a differential operational section, a data processing section and a recording and displaying section, respectively, as will be hereinafter explained. The first chamber 3 of the capsule 1 has an opening, so that the capsule 1 can closely contact the skin 2 at the opening. The humidity sensor 4 disposed within the second chamber 6 is a capacitance type sensor such as a ceramic humidity sensor which varies its electric capacity according to the relative humidity of the diffused mixture produced in the first chamber 3. Such variation is immediately converted into variation in the frequency of the first oscillator 7, and is subsequently converted by the first F/V converter 12 into the voltage according to the frequency. The voltage thus obtained is amplified by the first amplifier 13, so that the output voltage of the first amplifier 13 corresponds to the sweating rate from the skin 2 superposing the ingredient caused by the variation in the temperature of the electric circuit forming the first oscillator 7. The second oscillator 8 is disposed on the same substrate as the first oscillator 7 and the circuit constant of the second oscillator 8 is so determined that the temperature characteristic of the electric circuit forming the second oscillator 8 is the same as that of the electric circuit of the first oscillator 7. Therefore, the frequency of the second oscillator 8 varies in the same manner as the frequency of the second oscillator 8 depending on the temperature. The output signal of the second oscillator 8 is supplied to the differential amplifier 17 through the second F/V converter 15 and the third amplifier 16. The output voltage of the differential amplifier 16 thus corresponds to the sweating rate from the skin 2 eliminating the ingredient caused by the variation in temperature of the first oscillator 7. The output of the differential amplifier 16 is processed by a digital calculating circuit 18 together with the output of the second amplifier 14 which corresponds to the temperature of the diffused mixture detected by the second amplifier 14, so that the sweating rate and the temperature variation of the capsule 1 is recorded by a pen-recorder 19, and the total amount of sweat during a predetermined test period, and the average sweating rate and the frequency of sweating during a unit of time are printed as digital values by a printer 20. Referring to FIG. 2, the circuit diagram of the digital calculating circuit 18 is shown in detail. The digital calculating circuit 18 includes a CPU (microprocessor) 21 as a main part. The output of the differential amplifier 17 corresponding to the relative humidity and the output of the second amplifier 14 corresponding to the temperature of the diffused mixture are converted into digital values by an A/D converter 22 and are stored in RAM 23 as measured data. The CPU 21 corrects the measured data so as to obtain the absolute sweating rate which is independent of the temperature, and linearizes the same based on a calculation program and a calculation table which are written in a P-ROM 24. The CPU 21 further calculates the total amount of sweat during a predetermined test period, the average sweating rate and the frequency of sweating during a unit of time, the temperature of the capsule 1, etc. which are stored in the RAM 23 as calculated data. The calculated data concerning the sweating rate and the temperature of the capsule 1 stored in the RAM 23 is converted into analogue data by a D/A converter 25 and is recorded by the pen-recorder 19. The calculated, data can be directly transmitted to the printer 20 through an output port 26 and a printer interface 27, so that they can be printed as digital data by the printer 20. The printer 20 may print the other digital data than the calculated data. All the data can be supplied to an external general purpose computer through a serial interface 28 which is connected with a data bus. A timer 29 administrates the period of measurement, the time of measuring, etc. The detecting section for detecting the sweat and the temperature shown in FIG. 1 will be hereinafter described with reference to FIG. 3. The capsule 1, the first chamber 3, the humidity sensor 4, the second chamber 6 and the oscillator 7 form a sweat detecting section. On the other hand, an inlet port 30, a communicating hole 31 connecting the first chamber 3 with the second chamber 6, an outlet port 32 and the air channel 9 form an air supply passage. The water vapor perspired from the skin 2 and filled in the first chamber 3 is diffused and mixed with the dehumidified air supplied from the air channel 9 through the inlet port 30. The diffused mixture flows into the second chamber 6 through the communication hole 31 and thereafter flows out of the capsule 1 through the outlet port 32. As the sweating rate varies, the capacitance of the humidity sensor 4 disposed within the second chamber 6 also varies, and consequently the frequency of the first oscillator 7 varies. The output of the first oscillator 7 is supplied via a line 33 to the first F/V converter 12 and thereafter to the first amplifier 13. The output of the first amplifier 13, therefore, corresponds to the relative humidity of the diffused mixture in the second chamber 6. On the other hand, the temperature sensor 5 disposed in the second chamber 6 outputs the voltage signal based on the variation of its resistance. The output of the temperature sensor 5 is supplied to the second amplifier 14, so that the output of the second amplifier 14 corresponds to the temperature in the second chamber 6. The seconed oscillator 8 is disposed on the same substrate as the first oscillator 7 and is connected to the second F/V converter 15 via a line 35 and subsequently to the third amplifier 13. The variation in the output voltage of the third amplifier 13, therefore, corresponds to the variation in the frequency of the second oscillator 8 caused by the temperature variation in the electric circuit forming the second oscillator 8. Referring to FIGS. 4 and 5, shown therein is a device for continuously measuring the skin local sweating rate according to a second embodiment of the present invention. As shown in FIG. 4, a capsule 51 of relatively small size has a first chamber 53 and a second chamber 56. The first chamber 53 produces a diffused mixture of sweat or water vapor and a dehumidified air. The second chamber 56 includes therein a humidity sensor 54 and a temperature sensor 55. The humidity sensor 54 is electrically connected with a first oscillator 57. The first chamber 53, the humidity sensor 54, the temperature sensor 55, the second chamber 56 and the first oscillator 57 form a detecting section for detecting the sweating rate and the temperature. A second oscillator 58 is disposed on the same substrate as the first oscillator 57 and forms a temperature compensation section of the first oscillator 57. A portable box 59 accommodates an electric circuit for processing the data signal from the first oscillator 57, the second oscillator 58 and the temperature sensor 55 as will be hereinafter explained. The portable box 59 also accommodates air supply means for supplying a dehumidified air to the first chamber 53 of the capsule 51 through an air channel 78. A Holter's electrocardiograph 60 constitutes a long-time recording section and records on a micro cassette tape 61 the detected signal corresponding to the sweating rate and the detected signal corresponding to the temperature of the mixture which have been modulated into low frequency by the electric circuit in the portable box 59. The holter's electrocardiograph 60 as well as the capsule 51 and the portable box 59 are portable by a subject of the test. On the other hand, a regenerator 62 of Holter's cardiogram for regenerating the signal recorded on the micro cassette tape 61, a first and a second F/V converter 63, 64 for demodulation, a digital calculating circuit 65, a pen-recorder 66 and a printer 67 which are connected with the regenerator 62 are stationarily disposed. The first chamber 53 of the capsule 51 has an opening, so that the capsule 51 can closely contact a skin 52 of a human body at the opening. The humidity sensor 54 disposed within the second chamber 56 is of a capacitance type, and its electric capacity varies with the relative humidity of the diffused mixture which has been produced in the first chamber 53 and enters the second chamber 56 through a communicating hole 90. Such variation is immediately converted into the variation in the frequency of the first oscillator 57. The second oscillator 58 is disposed on the same substrate as the first oscillator 57 and the frequency of the second oscillator 58 varies in the same manner as the frequency of the first oscillator 57 which depends on the temperature. The temperature sensor 55 is disposed in the second chamber 56 and detects the temperature of the diffused mixture. The output signals of the first and second oscillators 57, 58 are received by the electric circuit within the portable box 58, which modulates these signals into low frequency, and are recorded on the micro cassette tape 61 set in the Holter's electrocardiograph 60 as modulated signals corresponding to the sweating rate. The output signal of the temperature sensor 55 is also received and modulated by the electric circuit within the portable box 58 and is thereafter recorded in the micro cassette tape recorder 61 of Holter's electrocardiograph 60 as a modulated signal corresponding to the temperature. After the measurement of the sweating rate, the micro cassette tape 61 ejected from the Holter's electrocardiograph 60 is set in the regenerator 62 of Holter's cardiogram. The regenerator 62 regenerates the modulated signals corresponding to the sweating rate and the temperature recorded in the micro cassette tape 61 at high speed. The regenerated signals are demodulated into the variation in voltage by the first and second F/V converters 63, 64. The digital calculating circuit 65 corrects the demodulated signal to obtain the real sweating rate which is independent of the temperature, and calculates the total amount of sweat during a predetermined test period, the average sweating rate and the frequency of sweating during a unit of time, and the temperature of the capsule 51. The pen-recorder 66 records the data concerning the variation in the absolute sweating rate and the temperature. The printer 67 prints as digital values the total amount of sweat during a predetermined test period, and the average sweating rate and the frequency of sweating during a unit of time. The construction of the portable box 59 and the operation of the electric circuit disposed therein will be hereinafter explained with reference to FIG. 5. The first oscillator 57 outputs a signal which includes the ingredient caused by the variation in the temperature of the diffused mixture superposed on the ingredient caused by the variation in the temperature of the first oscillator 57 itself. The second oscillator 58 outputs a signal which includes the ingredient caused by the variation in the temperature of the oscillator 58 itself. The output of the first and second oscillators 57, 58 are changed into the voltage by the first and second F/V converters 84, 85, respectively, and are supplied to a differential amplifier 86 so as to be differentially amplified. The differential amplifier 86 thus outputs a signal corresponding to the sweating rate from the skin 52 in which the ingredient corresponding to the variation in the temperature of the first oscillator 57 has been eliminated. The output of the differential amplifier 86 is modulated by a third V/F converter 87 into low frequency such as 10 to 100 Hz for recording on the micro cassette tape 61 set in the Holter's electrocardiograph 60. The output of the temperature sensor 55 which detects the temperature of the diffused mixture in the second chamber 56 is amplified by an amplifier 83 and thereafter modulated into low frequency by a fourth V/F converter 88. The air supplied from a compressor 80 of small, size is dehumidified by a silica gel box 79 and is supplied to the first chamber 53 of the capsule 51 through the air channel 78. The silica gel box 79 has two chambers 81 and 82 which are separated from each other and are connected in series through a small communicating hole 89, so that the the air can be effectively dehumidified. In this embodiment, the micro cassette tape 61 set in the Holterls electrocardiograph 60 may also record the data concerning the cardiogram as well as the data concerning the sweating rate and the temperature. Further, an IC card, etc. can be used as recording means other than the Holter's electrocardiograph 60. Additionally, data concerning the blood pressure, respiration, etc. may be simultaneously recorded with the data concerning the cardiogram, so that the diagnosis of function of human body can be effectively performed. While the invention has been described with reference to preferred embodiments thereof, it is to be understood that modification or variation may be easily made without departing from the scope of the present invention which is defined by the appended claims.

Claims: A device for continuously measuring the skin local sweating rate comprising: a capsule (1;51) for application to the skin at a measuring point; air supply means (9-11;78-82,89) for supplying dehumidified air to said capsule (1;51); a first chamber (3;53) formed between said capsule (1;51) and the skin for receiving water vapour perspired from the skin and the dehumidified air supplied from said air supply means (9-11;78-82,89) to produce a mixture of the said water vapour and the dehumidified air; humidity detecting means (4;54) varying its electrical circuit characteristic according to the relative humidity of the mixture; humidity detecting signal output means (7;57) mounted on said capsule (1;51) and electrically connected with said humidity detecting means (4;54) for outputting a detected humidity signal corresponding to the circuit characteristic of said humidity detecting means (4;54); calculation means (17,18;86,65) for calculating the sweating rate from the signals from said humidity detecting signal output means (8;58); and recording means (19;66) for continuously recording the data of the sweating rate obtained by said calculation means (17,18;86,65); characterised by: temperature detecting means (5;55) for detecting the temperature of the mixture and for outputting signals corresponding to the temperature; temperature compensation signal output means (8;58) disposed in the vicinity of said humidity detecting signal output means (7;57) and having the same electrical construction and the same temperature characteristic as said humidity detecting signal output means (7;57), said temperature compensation signal output means (8;58) outputting a temperature compensation signal substantially corresponding to the temperature of said humidity detecting signal output means (7;57), said temperature compensation signal being supplied to said calculation means (17,18;86,65) so as to compensate said humidity detecting signal; a second chamber (6;56) formed within said capsule (1;51) and connected with said first chamber (3;53) through a communicating hole (31;90) for allowing the mixture to flow from said first chamber (3;53) into said second chamber (6;56) and wherein the humidity and temperature detecting means (4,5;54,55) are disposed to detect the humidity and temperature of the mixture in the second chamber (6,56), and in that said calculation means (17,18;86,65) is adapted to calculate the sweating rate which is corrected in dependence on the temperature of the mixture based on the signal from said temperature detecting means (5,55). A device according to claim 1, further comprising: a portable box (59) having said air supply means therein (78-82,89); and portable record means (60) for continuous long-time recording of information concerning a function of a human body on detachable recording media (61), so that said humidity detecting signal and said temperature detecting signal can be recorded by said portable record means (60). A device according to claim 2, further comprising: a base station including regeneration means (62) for regenerating and demodulating said signals recorded on said detachable recording media (61), said calculation means (65) for calculating the sweating rate from said signals demodulated by said regeneration means (62), and said recording means (66) for continuously recording the data of the sweating rate obtained by said calculation means (65), said recording means (66) being adapted also to indicate said data.

Inventors: KAMEI TOMOYA C O SUZUKEN CO LT, OHHASHI TOSHIO, ONO NOBUYUKI, SAKAGUCHI MASAO, KAMEI, TOMOYA, C/O SUZUKEN CO. LTD., OHHASHI, TOSHIO, ONO, NOBUYUKI, SAKAGUCHI, MASAO
Applicants: SAKAGUCHI MASAO, SUZUKEN KK, SAKAGUCHI, MASAO, SUZUKEN CO. LTD.
Application year: 1990
Main classification: A61B5
IPC codes: A61B5