GB2329022A - Clothing mounted temperature sensor - Google Patents

Abstract

An inner sole (6) for a shoe carries a plurality of thermistors (9a-9f) which are arranged spaced apart along the inner sole so as to be thermally isolated from the inner sole and so as to stand slightly proud of the upper surface of the inner sole. These thermistors enable the temperature distribution across the sole of a foot within a shoe to be determined while, for example, the wearer is running or walking. Also a shoe has means responsive to pressure applied by the wearer's foot during use to cause heat to be transferred from the interior of the shoe to the outside. The heat conducting means may, for example, comprise a collapsible bladder which collapses under the pressure of the wearer's foot so as to bulge outwardly of the shoe and to cause heat conducting fluid to come into contact with the atmosphere thereby enabling heat transfer to atmosphere.

Description

A TEMPERATURE SENSING DEVICE AND ITEMS OF CLOTHING This invention relates to a temperature sensing device especially but not exclusively for detecting the temperature of the foot and items of clothing such as shoes for enabling temperature regulation.

Considerable research has been undertaken into the modern sports shoe with the aim of providing for shock absorption and support for the athlete while enabling the use of lightweight materials which do not hinder the athlete's performance and also reduce or at least mitigate the possibilities of injury.

It is well understood that regulation of the temperature of the human body is primarily affected by the temperature of the extremities. The human body can tolerate only a drop of 10 C and an increase of 5"C in the deep core temperatures and it is vital that the core temperature of the body, especially the deep tissues, remains balanced this meaning, in human beings, that the temperature is maintained in a narrow range of 36.1"C to 37.8"C. Maintenance of the correct core temperature is of particular concern to athletes taking part in long duration events especially under extremes of heat and humidity. The problems of core temperature regulation are also of concern to the military for similar reasons.

In order to maintain the body core temperature, most shoes are thermally insulated. However, the overall effects of sports shoes and military wear shoes, in particular, on the temperature distribution within the feet after long periods of wear and thus the effect of those shoes on the human temperature regulatory system are not well understood because it is difficult to measure the temperature of the foot inside a shoe. For example, thermal cameras and the like cannot be used.

In one aspect the present invention provides a device for determining the temperature profile of an area of the human body such as the foot. The device may comprise, for example, an item of clothing in which temperature sensors such as thermistors are distributed.

In another aspect, the present invention provides an inner sole for a shoe such as a sports shoe or military boot at predetermined locations of which are mounted thermal sensors such as thermistors.

In another aspect, the present invention provides an item of clothing or an inner for a shoe or glove carrying temperature sensors such as thermistors thermally isolated from the item of clothing or inner.

In another aspect, the present invention provides an item of clothing such as, for example, a glove or shoe having means for conducting heat from the interior to the exterior of the item of clothing.

In another aspect, the present invention provides a shoe having means responsive to the pressure of the foot on the sole of the shoe such as may occur when the heel or toe of the shoe hits the ground during walking or running, to conduct heat from the interior to the exterior of the shoe.

The heat conducting means may comprise, for example, a collapsible bladder. The collapsible bladder may, for example, be connected to heat conducting tubing running around the outside of the shoe. The collapsible bladder contains a heat transfer material such as for example a suitable oil such as a mineral oil or other type of oil used for cooling purposes or even possibly water.

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows schematically a side elevational view of a sports shoe.

Figure 2a is a plan view of an inner sole for sensing the temperature profile within a shoe during use; Figure 2b is a cross-sectional view taken along the line 2-2 in Figure 2a; Figure 3 shows a circuit diagram for deriving an output voltage representative of temperature from a thermal sensor carried by the inner sole shown in Figure 2a; Figure 4 shows processing apparatus for processing the output of the circuit shown in Figure 3; Figures 5a to Sc show temperature distribution profiles along the inner sole shown in Figure 2a prior to commencement of exercise, and ten and twenty minutes, respectively, into a period of exercise.

Figures 6 and 7 are schematic side elevational views showing shoes embodying the present invention.

Referring now to the drawings, as shown in Figure 1, a sports shoe 1 generally comprises a canvas or mesh-like upper which may, although not shown, have regions of leather or plastics material for reinforcement and support, especially in the ankle area. The shoe is provided, as is conventional, with a lace 3 closing arrangement.

The sole 4 of the shoe comprises a synthetic rubber or similar layer designed to cushion the foot against impact and also provides support. The rear of the sole may be provided with an added cushioning layer 4a which again may be formed of a synthetic rubber, for example.

As will be appreciated by those skilled in the art, the sole may also incorporate gels and other materials or honeycomb structures so as to increase lightness and provide cushioning for the foot of the athlete as it impacts the ground. A lower layer 5 of the shoe is profiled to provide a tread to provide both support and grip during use.

Figures 2a and 2b illustrate an inner sole 6 embodying the invention. The inner sole 6 is based on a conventional inner sole having a polyethylene lower layer 7 and a fabric cover 8 which is designed to absorb sweat from the foot of the user. In the inner sole embodying the invention, a number of temperature sensors 9 are embedded into the inner sole. In this example, each of the temperature sensors comprises a thermistor which may be, for example, a negative (NTC) or positive (PTC) temperature coefficient thermistor such as supplied by Siemens AG of Munich Germany for example their NTC B57867530 series of surface mount thermistors, their BS9701 series of PTC thermistors or the 23226405xxx series of NTC thermistors supplied by Philips Electronics NV of Eindhoven the Netherlands.

In the arrangement shown in Figure 2a, two thermistors 9a are located adjacent the heel of the inner sole, a single thermistor 9b is located centrally under the area where the arch of the foot would be in use. Two thermistors 9c are located symmetrically at about the location of the ball of the foot in use and two further thermistors 9d and 9e are located adjacent the big and little toes. Another thermistor 9f is located midway between the thermistors 9c and 9d and e.

Each of the thermistors is located in an aperture 10 formed in the inner sole 6 which is larger than the thermistor. The thermistor is held in place in the aperture 10 by means of a thermally insulating epoxy resin 11 so that the thermally responsive surface 9a of the thermistor stands proud of the upper surface 8a of the inner sole. The isolation of the thermistors from the surrounding inner sole serves to ensure that the detected temperature is not affected by the inner sole while the fact that the thermistors stand proud of the inner sole enables good contact with the foot of the athlete. The amount by which the thermistors stand proud of the surface 8a is of the order of only lmm or 2mm and the surfaces of the thermistors are rounded and so should not cause any discomfort to the athlete during use.

Wires from each of the thermistors are lead out along the rear surface 7a of the inner sole and are secured in place by means of a lower thin synthetic rubber layer 12 which is fixed by adhesive to the lower surface 7a of the inner sole.

The output leads from the thermistors are supplied via a cable 13 to respective signal processing circuits.

Figure 3 shows an example of the signal processing circuit 14 for one thermistor.

As can be seen from Figure 3, each thermistor which is, in the present case, a 15 kilo-ohm thermistor, is coupled in series with two series connected 10 kilo-ohm resistors R1 and R2 between a 15 volt supply line 15 and a ground or earth line 16. The resistor R2 is also coupled to the cathode of a 2.2 volt Zener diode whose anode is coupled to the ground supply line 16. The junction J1 between the resistor R1 and the thermistor 9 is coupled to the positive input of an operational amplifier OA1, for example a TL064N operational amplifier. The negative input of the operational amplifier OA1 is coupled to its output. Power is supplied to the operational amplifier by plus and minus 15 volt power supply lines 15 and 17 which are connected to the ground supply line 16 via respective 1.5 micro Farad capacitors C1 and C2.

The output V from each of the circuits 14 may be supplied to a conventional data logger, for example.

Alternatively, the outputs V from the circuits 14 may be supplied to an input/output interface of a personal computer which acts as a processing apparatus. Figure 4 shows schematically one example of such apparatus.

In the arrangement shown in Figure 4, the outputs V from the, in this example, eight sensors 9 are input to a multiplexer MUX and supplied via an operational amplifier OA2 to an analogue-to-digital converter 18 which may form part of, for example, the sound card of the computer. The digitised output of the analogue-todigital converter is supplied to a RAM 11 of the computer with operation of the multiplexer, analogue-to-digital converter and RAM being under control of the central processing unit of the processing unit or mother board 10 of the computer. As is conventional, the computer also comprises a ROM 12, a hard disc drive 13, a floppy disc and/or CD ROM drive 14 into which a disc FD can be inserted to enable storage of data or supply of program instructions to the processor. The computer also has a keyboard 15a and a mouse 15b for enabling interaction with a user, a monitor 16 for displaying data and instructions to a user and a printer 17 for enabling a hard copy of the data to be obtained. The computer may also be equipped with a transceiver 18 such as a modem or infrared port to enable communication with other computers.

The thermistors 9 may be calibrated against a known standard temperature sensor such as an accurate thermocouple by, for example, placing the inner sole and the thermocouple in an oven and ramping the temperature up in known degree steps. The calibration information may then be stored in the RAM 11 of the computer.

Experiments were carried out in which a person ran on a treadmill at a speed of approximately 10km/hour wearing an inner sole as shown in Figure 2a in his sports shoes. The processing circuitry shown in Figure 14 may be, in this example, incorporated in a belt or thigh strap worn by the user and connection from the processing circuitry 14 to the processing apparatus 9 may be provided either via a long flexible cable or by a remote telemetry link such as an infrared or radio telemetry link.

The outputs from the nine temperature sensors were logged and processed by the processing apparatus 9 to produce the charts shown in Figures 5a to Sc which plot temperature T in degrees Celsius on a vertical axis while the x and y axes represent the area of the inner sole.

the locations of the thermistors 9 are represented by cones C of a height determined by the measured temperature. For convenience, the actual measured temperature for each of the cones C is given on the graphs.

Figure 5a shows the temperature distribution on the inner sole before exercise commenced. Figure Sb shows the temperature distribution after ten minutes running at approximately 10km/hour on the treadmill while Figure Sc shows the temperature distribution after twenty minutes of running. As can be seen from these graphs, the temperature especially at the heel and under the ball of the foot rises markedly during exercise reaching a level of about 44-46"C under the ball of the foot after only twenty minutes of this relatively moderate exercise.

An inner sole embodying the invention may thus be used to determine the temperature distribution across the sole of a foot within a sports shoe during exercise. Of course, as will be appreciated, a large number of thermistors 9 may be provided in the inner sole so as to provide a more detailed profile of the temperature of the foot. Also, it may be possible to provide only one of the temperature sensors 9a and 9c because the temperature distribution across the heel and ball of the foot in the lateral direction (that is transverse to the heel/toe direction) is approximately symmetrical.

As an alternative to incorporating the thermistors into an inner sole, the thermistors may be incorporated into a sock or inner shoe to be worn by the athlete within their sports shoe. This would enable the temperature profile on the top of the foot as well as on the sole of the foot to be measured.

Also, the temperature distribution of other areas of the body may be measured by, for example, incorporating the thermistors into, for example, gloves or hats, vests or other garments.

Also, temperature sensing devices other than thermistors may be used such as thermocouples although care would need to be taken to avoid damage to the athlete during use. It may also be possible to use other forms of temperature sensitive semiconductor devices.

Figure 6 shows schematically an example of a shoe la embodying the invention which is provided with means for facilitating regulation of the temperature of the foot by conducting heat from the interior of the shoe to the outside. In the example shown in Figure 6, the sole 4 of the shoe beneath the area where the ball of the foot would be in use is formed with a concavity 40 and a corresponding concavity 40a is formed in the raised portion 4a of the sole where the heel would be in use.

A flexible synthetic rubber or plastics bladder 20 is incorporated into each of these cavities so that at least a portion of the bladder extends to the exterior of the shoe. Each bladder 20 is filled with a heat conducting material such as for example a suitable oil such as a mineral oil or other type of oil used for cooling purposes or even possibly water. In use of the shoe, when the athlete presses on either of the bladders as his heel or toe, as the case may be, hits the ground during running or walking, the bladder is caused to collapse and the heat conducting fluid within the bladder is forced outwardly to the exterior of the shoe where heat transferred from the sole or ball of the foot can be conducted to atmosphere. In order to prevent the pressure of the foot collapsing the bladder so completely that fluid cannot flow to the outside of the shoe, the upper or sole of the shoe in the region of the bladder may be formed with a reinforced aperture through which the bladder can protrude to the outside.

Figure 7 illustrates a modification of the shoe shown in Figure 6 in which each of the bladders 20 couples to a heat conductive hollow tube 21 which runs round, respectively, the heel or toe of the shoe 1b so that each end of the tube communicates with the bladder to provide a greater surface area from which heat can radiate. Again, pressure of the athlete's foot during walking or running causes fluid to be forced out of the bladder into the tube where heat can be conducted to atmosphere.

When the athlete lifts his heel or toe off the ground, the cooled fluid returns to the bladder where it can absorb heat from the interior of the shoe until the next time the foot presses on that particular bladder.

The bladders 20 may be shaped to cover any desired area of the ball and heel of the shoe.

Although the shoes shown in Figures 6 and 7 are socalled training shoes it will, of course, be appreciated that the same principles can be applied to other forms of sports shoes such as running shoes, rugby boots, cricket boots and the like and also to walking boots and military footwear or even everyday footwear.

As an alternative to a deformable bladder, a piston arrangement may be used wherein the piston is biassed, for example by spring biassing means, in an upwardly direction and is forced downwards by the pressure of the foot to cause heat conducting fluid to be pumped from a reservoir in the sole of the shoe to a portion of the reservoir or a heat conducting tube which extends on the outside of the shoe to enable conduction of heat to atmosphere.

The principles shown in Figures 6 and 7 for conducting heat to the exterior of the shoe may also be applied to other items of clothing such as, for example, gloves. However, in such cases, it would be necessary for the user to actively activate the bladder by physically pressing upon the bladder.

Claims (12)

1. A device for sensing the temperature distribution of an area of the human body comprising a substrate carrying one or more temperature sensing devices.

2. A device according to claim 1, wherein a plurality of temperature sensing devices are spaced apart over the substrate.

3. A device according to claim 1 or 2, wherein the or each temperature sensing device comprises a thermistor.

4. A device according to any one of the preceding claims, wherein the or each temperature sensing device extends slightly beyond the surface of the substrate which, in use, will contact the skin.

5. A device according to any one of the preceding claims, wherein the or each temperature sensing device is thermally isolated from the substrate.

6. An inner sole for a shoe comprising a substrate having formed therein a plurality of apertures arranged spaced apart at locations along the substrate so that at least one aperture is provided at the heel of the inner sole and at least one aperture in the region where the bulk of the foot would be in use of the inner sole, a respective thermistor being mounted in each of the apertures by means of a thermally isolating adhesive which spaces the thermistor from the inner sole, the mounting of the thermistors being such that each thermistor stands slightly proud of the upper surface of the inner sole.

7. An inner sole substantially as hereinbefore described with reference to Figures 2a and 2b.

8. An item of clothing comprising means for conducting heat from an inner surface of the item of clothing to atmosphere.

9. A shoe comprising means for conducting heat from the interior of the shoe to atmosphere.

10. A shoe according to claim 9, wherein the heat conducting means comprises at least one bladder containing a heat conductive fluid, the bladder being deformable under pressure applied by the foot during use of the shoe so as to force the heat conducting fluid to the outside of the shoe to enable heat to be transferred to atmosphere by the heat conducting material.

11. A shoe according to claim 10, further comprising a heat conducting tube extending from the or each bladder around a portion of the shoe to facilitate transfer of heat from the heat conducting material to atmosphere.

12. A shoe substantially as hereinbefore described with reference to, and as illustrated in, Figures 6 or 7 of the accompanying drawings.