GB2444145A - Body temperature detection clothing piezoelectrically powered from body motion - Google Patents

Abstract

A detector device, for sensing skin temperatures as an aid to diagnosis of cancers or pre-cancers, comprises piezoelectric yarns or fibres (14, fig 3) in a textile fabric which is made up into a garment such as briefs, brassiere or bodice, etc. to generate electricity due to flexure during movement of the body, e.g. in respiration. The fabric also contains thermal detectors with microwave signal generating elements (12, fig 4) which transmit a temperature related signal to a sensor and a microprocessor.

Description

I

Temperature Detection The present invention relates to the detection of temperature in particular as evidenced by electromagnetic radiation emitted from a body at microwave frequencies, and primarily of use in medical detection.

The levels of electromagnetic radiation emitted by a human body are proportional to the subsurface temperature of the body tissue. In diagnosis, use is made of the fact that thermal changes in the body are caused by illness, malfunctioning of internal organs, cell metabolism, physical stress and the like, some of which can lead to cancer. Internal thermal changes in tissue can lead to or be caused by anatomical or tumour generating changes. These changes can be detected using established non-invasive techniques including ultrasound, x-rays, or MRI or invasive methods including biopsy.

Infra-red thermography involves imaging of the exterior of all or part of the body at infra-red frequencies to measure external temperature variations on the time surface.

Breast cancer is the most common cancer among women, whilst prostate cancer is the most common cancer in men, other than skin cancer. It is the leading cause of cancer related deaths in people aged between 40 and 55. Screening and early diagnosis are currently the most effective ways to reduce mortality from this cause. It is a well known and established fact that the success in curing such cancers with therapeutic treatments increases substantially if they are detected at an early stage.

There exist a number of methods and techniques available to facilitate detection and diagnosis of such cancers including self awareness and examination, clinical tests, mammography, magnetic resonance imaging and so on. However, they are capable of analysing the existing condition and require trained personnel to use the equipment.

Meanwhile, the detection of the earliest forms of cancers has recently increased significantly worldwide, and this is attributed to the successful medically assisted screening programs which are expensive, time consuming and require the patient to visit the expert medical practitioner. There are no effective early warning systems available that are self indicating and can be used without the assistance of qualified personnel.

US 4,055,166 (Simpson) proposes the use of a brassiere which includes a number of skin temperature sensors, for detecting the presence of tumourS by measuring the surface temperature at points on the breast. The sensors comprise silicon transistors, the conductivity of which varies with the temperature of the transistor. These sensors are connected to circuitry which enable the temperatures determined to be recorded and accessed for interpretation. US 6179786 (Young) provides an apparatus for sensing the temperatures of breast tissues in a breast cancer risk assessment system, the apparatus comprising a harness to be worn on the breast wherein a number of temperature sensors are arranged in a ring around the aureole area. The sensors are connected electrically to a monitor unit which records the data produced and then can provide the data for interpretation. The sensors are temperature monitor integrated circuits of the temperature in -current out type.

The coverage of the sensors in both prior patents is discontinuous and without the use of an expensive and burdensome number of sensors provides incomplete coverage which leaves the temperatures of intermediate zones to be inferred.

It is therefore an object of the present invention to provide a device which lends itself to the early detection of subsurface tissue abnormalities, which are usually warmer than the unaffected tissue, and which can develop into cancerous cells and subsequently tuniours.

The invention accordingly provides a device for detecting variations in body tissue temperatures which comprises thermal detector elements to be worn in relation to the body, and yarns or fibres are incorporated in the device which contain piezo-electric filaments which respond to movement of the body due for example to respiration to generate electrical energy.

The detector elements may be connected to a micro-processor, preferably through a threshold gating system which filters out all normal temperature indications.

An audible alarm or signal light alarm, or both may be provided to be activated by detection of an abnormality.

The piezo-electric fibres may be incorporated as a core element in a yarn, which is preferably incorporated by weaving or otherwise into a garment to be worn by the test subject. The garment may according to the gender of the subject be embodied as briefs or as a brassiere or bodice.

The piezo-electric fibre or yarn material preferably comprises PZT (lead zirconate titanate) which is a piezo-electric ceramic material, or may comprise polyvinylidene fluoride and its co-polymers (referred to as PVDF hereinafter), which is a polarised fluoropolymer.

The thermal detector elements preferably comprise thermally sensitive micro-wave signal generating elements also incorporated in the textile fabric, which are excited by current generated in the piezo-electric fibre cores, to create a temperature related signal which can be detected by a sensor connected to the micro-processor.

These, and the piezo-electric yarns or fibres, may be distributed throughout the garment, being incorporated uniformly in the fabric from which the garment is made, or concentrated in higher risk zones, that is in the cups of a brassiere for detection of breast cancer, or in the groin area of briefs for detection of prostate cancer.

The fabric may also include electrically conductive polymer fibres, to connect the piezo-electric material to the sensor.

Preferred embodiments of temperature detection apparatus for detecting anomalies in body heat, in accordance with the invention, will now be described by way of example, with reference to the accompanying drawings, wherein:-Figure 1 is a diagrammatic view of a garment for wear by a female for detecting body heat anomalies; Figure 2 is a similar view of a garment for wear by a male for detecting body heat anomalies; Figure 3 is an enlarged view of temperature detector yams to be incorporated into a garment such as shown in Figure 1 or 2; Figure 4 is an enlarged view of microwave transmitter elements to be activated for signalling by body heat measurements, also for incorporating into a garment such as shown in Figure 1 or 2; Figure 5 is a schematic layout of the components of the device according to the invention; Figure 6 illustrates a first operating mode of the device; Figure 7 illustrates a second operating mode; Figure 8 is a flow diagram showing operation of the device; Figure 9 is a further diagram showing operation of the device; and Figure 10 illustrates further operating mode of the device.

Figures 1 and 2 respectively illustrate temperature detector garments for use in for example cancer diagnosis. Figure 1 shows a female gannent in the form of a brassiere 10, which has detector means built into the cups in order to be in contact with the skin of the breasts, to directly sense the surface temperature of all or most parts thereof.

Figure 2 similarly shows a male garment in the form of a brief or thong 11, which has detector means built into the groin covering area, for the purpose again of directly sensing the surface temperature of all or most parts of the groin area.

Detector elements are woven into the fabric of the garments 10, 11, and include transmitter elements, in the form of antenna discs 12 are distributed over the area of the respective garment to be monitored for occurrence of temperature anomalies. These are exaggerated in size in Figures 1 and 2 for clarity and may be more closely spaced. Each disc 12 has an associated LED, shown as a central spot in each disc in the drawings. The LED's of the sensors 12 over a detected hot spot' will illuminate to show the extent and intensity of the localised anomaly so that the site can then be appropriately investigated, to elimate non-cancerous causes, such as may be caused by localised bacterial or virus infections such as skin abscesses or inflamrnations, swollen lymph glands, or the like. These can then be treated and monitored to ensure that any tissue damage which can lead to cancer later can be detected.

Suspected cancerous sites can also be subjected to biopsy, or monitored and treated with appropriate therapy. * 6

Elements including piezoelectric fibres in the form of yarns 13 are shown in Figure 3, where a short section of a number of parallel yarns 13 are shown. Each yarn 13 comprises a core filament 14 of a piezo-electric material such as lead zirconate titanate (PZT) which is a ceramic material, or polyvinylidene fluoride and its co-polymers (PVDF), which is a polarised fluoropolymer. The core 14 is enclosed in a sheath 15 of an electrically conductive fibre material. This may be a metallic film coating instead. These yarns are woven or laid in the fabric from which the garments 10, 11 are made and create electricity in response to flexure due to breathing by the

subject for example.

The microwave elements 12, are in actual fact smaller and more closely spaced than the discs shown in Figures 1 and 2, and are shown magnified, in Figure 4.

In use, the garment may be worn at say weekly intervals as part of a self- checking routine by the subject. The garment is used in conjunction with a micro-processor which establishes a reference image of the normal' condition of the heat distribution over the body area concerned, such as the breast or groin.

in subsequent sessions, the image or map obtained is compared with the reference image, and any deviations, particularly the occurrence of a new hot spot' which was not detected previously, can be used to trigger an audible and/or visual alarm. The visual alarm may include the illumination of the LED's 15 over the area in which the hot spot' is detected.

The subject, thus alerted can then consult a medically qualified person to carry out a proper examination to determine the cause and treat a non-cancerous infection, or undertake appropriate tests, monitoring and treatment for a suspect cancer or pre-cancer.

This monitoring routine can be carried out by the subject in his or her own house, by themseif without intervention by Irained medical personnel.

Figure 5 shows a flow diagram of the operation of the device. The current generated by warming of the piezo-electric fibres 14 is applied to a control circuit which operates the LED 15 and audible alarm, and also a rectification circuit which goes to a storage medium, where the sensed heat distribution may be compared with a reference signal distribution.

Figures 6, 7 and 10 are diagrams showing possible flow diagram for different reference sources.

In Figure 6, the reference voltage, Vref, is derived from the maximum normal temperature value, for the zone concerned. This is compared with the voltage from the piezo-electric material 14, and if the latter is greater, a gate 20 is opened, which operates an alarm control to activate visual and/or audible alarms.

In Figure 7, the reference voltage is derived from the reference noise signal.

The signal from the piezo-electric material is amplified by amplifier 22 and then compared at 24 with the reference voltage, and a multiplexer feeds to a micro-processor (not shown) which processes the signal and makes an alarm or other indication as appropriate.

In Figure 10, the reference voltage is the maximum temperature difference.

Here the signal from the piezo-electric material 14 is applied directly to the micro-processor 26, which compares the signal with a memory table, subtracts the temperature difference, and applies the result to a gate 28 where it is compared with the reference voltage Vref, and if higher the alarm control is activated and an alarm is given. * 8

The device is based on passive electromagnetic radiation principles, i.e. electromagnetic radiation emitted from the subsurface body tissue. It is a non-invasive and non-hazardous technique. The detection and diagnosis is conducted by measuring the intensity of natural electromagnetic radiation of internal body tissues at microwave frequencies. This intensity is proportional to the tissue temperature.

Tumours have a significantly different index of refraction and the internal tissue temperature changes due to inflammation changes in the blood supply or with increased metabolism of cells during the oncological transformation of tissue.

The electromagnetic radiation power is governed by the equation: E=BxfxT where E = energy received by the antenna B = Boltzman's constant f = frequency band width T = subsurface body tissue temperature.

Temperature changes can be detected at depths up to 10 cm depending on tissue composition, structure, and condition of the patient. Overweight people have lower internal temperature while those with thyroid and lung diseases have higher internal temperature. Normal people exhibit internal temperature around 3 7 C, but women during menstruation undergo internal temperature variations. Therefore, it is preferable, if temperature measurements are made in room environment conditions (20 C) and ten days away from the menstrual cycle. Also the device must be operated in normal atmospheric pressure and relative humidity levels up to 80%.

The device is a non-intrusive, self indicating system that can be used for early detection of cancers. It is incorporated in the bra structure in the case of women and in the brief structure in the case of men. Fast growing tissue changes are easier to detect since the heat generated during growth is higher and thus early detection of tumours can be diagnosed. In women the device can be employed during pregnancy and lactation periods to monitor thermophysiological changes and for other self examination purposes.

Electromagnetic radiation emitted from the body is picked-up by the microwave antenna system, operating at 1-12 GHz frequency and close to the skin surface. The temperature information in the form of voltage is amplified through microelectronic circuitry which compares with reference noise signal of 0.2 dB. The time taken for each temperature measurement from the 9 microwave antennae which are multiplexed is about 10 seconds. The antennae are positioned concentrically and surround the whole area of the targeted tissue. Each flexible microwave antenna covers an area up to 20 mm2 depending on the chosen frequency which is dependent on the selected depth under investigation. It is capable of detecting electromagnetic signal strengths of 5 x 1(i' W with a resolution of 1010 W for temperature differentials of 0.1 C. The difference of approximately 1 C indicates an abnormality within3-10 cm in depth. For different depth measurements, microwave antennae of different sizes are required.

Signals are fed through a conducting polymer fibre system (e.g. Figure 8).

The conducting polymer fibre sheath surrounds a concentric polymer piezoelectric (PVDF) core fibre. This piezoelectric core fibre acts as a micropower generator and whenever it is flexed or stretched it produces a voltage output that is proportional to the stress induced into the piezoelectric fibre material. The voltage produced in response to flexing or stretching action is then fed through the conducting polymer fibre, and through it the energy generated is stored in a capacitor or used on-line, as per need. Considering the fact that the electromagnetic radiation passing through the S different layers of body tissue materials undergoes different losses at different temperature differentials, the temperature measured by the device is not the absolute temperature of the targeted region. For this, suitable electronic circuit can also compensate for any reflections encountered between tissue and antennae. A threshold gating system is employed by the micro-processor which filters out all normal temperature indications and whenever an abnormality is diagnosed, an audible alarm andior a single light alarm is powered.

Additionally it is proposed that the PVDF core fibre be used to measure surface body temperature and mechanical stresses within the bra or undergarment. By placing additional fibres at right angles to those placed concentrically it will be possible to identify the location of any temperature "hot spots" and points of maximum stress within the undergarment. The measure of surface temperature can also be an indication of cancerous growths and the mapping of changes can give an early indication of the formation of growth tissue. They also help compare and contrast microwave sensor values from core body measurements to piezoelectric body surface measurements, thus providing a better multifunctional system.

Furthermore, a double piezoelectric arrangement can help stabilise the tissue in the presence of vibrations during movement or exercise. In this configuration the two piezoelectric fibre structures embedded in the underwear work in tandem, one bending the piezoelectric fibres and senses the vibrations and generates a charge which is collected by the attached conducting polymer electrodes. The charge and associated current is carried to an embedded microchip containing inductors, capacitors and resistors which return the current back to the fibres out of phase to reduce any vibrations by destructive interference, thus passively damping vibrations by converting vibrations into electric charge, which is dissipated through a resistor.

While other materials including nylon and PVC exhibit the piezoelectric effect, they are not as highly efficient in transferring energy or as highly sensitive as PVDF (polarised fluoropolymer-polyvinylidene fluoride) and its co-polymers. PVDF is also pyroelectric, capable of producing electrical charges from temperature changes stimuli. PVDF is highly absorbent of infrared energy in the 7-20 p.m wavelength, which is the same wavelength spectrum as heat from human tissue. It can be manufactured in long fibres, cylinders and hemispheres, thus allowing other geometric coniigurations to be accommodated when it is interlinked with conducting polymers. Coatings of PVDF as thin as 200A, using the spin card technique, can be deposited on conducting polymer core fibres thus making this configuration an alternative design for the device. Alternatively a piezoelectric foam can be used as a padding that can also act as energy regeneration system.

In operation, the device compares incoming data with previously stored signals and contrasts values to identify potential temperature increases that correspond to sub-tissue activity/changes. Information monitored which exceeds the threshold level and supersedes the previous readings over a specified time penod, triggers the audio aridJor visual alarm. Alternatively, the updated temperature data can be displayed on a small screen andlor transmitted to a separate host micro-processor for further processing and analysis through thermographic depictions. * 12

The device avoids the use of metal wires or metal platings onto fabrics and thus it is not affected by any textile processing and postprocessing (launderability) methods. It is designed to be interwoven into the underwear fabric (bra or brief) that has a body fit, or it can be interwoven into a strap fabric to provide the same effect.

The invention is not limited to use in briefs or other underwear, but may be incorporated in all maimer of wearable articles, including socks or stockings or bandages for example for use in detecting ulcers or DVT (deep vein thrombosis). * 13

Claims (8)

1. Claims I. A device for detecting variations in body tissue

   temperatures, comprising thermal detector elements to be worn in relation to the body, and yarns or fibres are incorporated into the device which contain piezo-electric filaments which respond to movement of the body, for example due to respiration to generate electrical energy.
2. 2. A device according to claim 1, wherein the detector elements are connected to a micro-processor through a threshold gating system which filters out all normal temperature indicators.
3. 3. A device according to claim I or 2, wherein piezo-electric fibres are incorporated as a core element in a yarn which is incorporated by weaving or otherwise into a garment to be worn by a test subject.
4. 4. A device according to claims 1, 2 or 3, wherein the piezo-electric fibre or yarn material comprises PZT (lead zirconate titanate), or polyvinylidene fluoride.
5. 5. A device according to any preceding claim wherein the thermal detector elements comprise micro-wave signal generating elements incorporated in a textile fabric which includes the piezo-electric yarns or fibres and are incorporated uniformly in the fabric.
6. 6. A device according to claim 5, wherein the fabric also includes electrically conductive polymer fibres to connect the piezo-electric material to a sensor which detect signal created by the microwave generating elements.
7. 7. A device according to claim 5 or 6, wherein the fabric is made up into a garment to be worn by the test subject.
8. 8. A device according to claim 7, wherein the garment is embodied as briefs, or as a brassiere or bodice.