Support Evaluation Device

Abstract

A support evaluation device (10) comprising a series of pressure sensors in a stack (16), output means (34a, 34b, 34c) linked to the pressure sensors for indicating signals therefrom, and a power source, the series of pressure sensors including at least first and second pressure sensors within the stack (16), operational across respective first and second pressure bands, each pressure sensor including first and second electrical conductors (18, 20, 24, 28), and an insulator (22, 26, 30) separating the electrical conductors (18, 20, 24, 28), the pressure sensors being adapted to signal whether there is contact between their electrical conductors (18, 20, 24, 28), and the output means (34a, 34b, 34c) being adapted to provide at least one of an audio or visual output corresponding to signals from the pressure sensors, in use indicating the pressure band reached for a patient sat on the device (10), each pressure band corresponding to a predetermined cushion strength for prescribing a cushion to that patient.

Claims

1. A support evaluation device comprising a series of pressure sensors in a stack, output means linked to the pressure sensors for indicating signals therefrom, and a power source, the series of pressure sensors including at least first and second pressure sensors within the stack, operational across respective first and second pressure bands, each pressure sensor including first and second electrical conductors, and an insulator spacing the electrical conductors, the pressure sensors being adapted to signal whether there is contact between their electrical conductors, and the output means being adapted to provide at least one of an audio or visual output corresponding to signals from the pressure sensors, in use indicating the pressure band reached for a patient sat on the device, each pressure band corresponding to a predetermined cushion strength for prescribing a cushion to that patient.

2. A support evaluation device as claimed in claim 1, in which a third pressure sensor is also provided in the series of pressure sensors in the stack.

3. A support evaluation device as claimed in claim 1 or claim 2, in which at least one of the pressure sensors shares a common electrical conductor with another of the pressure sensors.

4. A support evaluation device as claimed in any of claims 1 to 3, in which the series of pressure sensors is concatenated in the stack, the electrical conductors and insulators being provided in alternating strata.

5. A support evaluation device as claimed in any preceding claim, in which the uppermost pressure sensor in the stack operates above a first pressure threshold, and each subsequent pressure sensor in the stack operates above a successively higher pressure threshold.

6. A support evaluation device as claimed in any preceding claim, in which the insulators are resilient and made of foam.

7. A support evaluation device as claimed in any preceding claim, in which the insulators are made of combustion modified high resilience (CMHR) foam.

8. A support evaluation device as claimed in any preceding claim, in which each insulator includes one or more apertures through which the electrical conductors can come into contact.

9. A support evaluation device as claimed in any preceding claim, in which the insulator in the uppermost pressure sensor of the stack is thinner than the insulators in the subsequent pressure sensors.

10. A support evaluation device as claimed in any preceding claim, in which each electrical conductor includes a carbon-printed surface.

11. A support evaluation device as claimed in any preceding claim, in which each electrical conductor includes carbon-printed polythene.

12. A support evaluation device as claimed in any preceding claim, in which the output means includes a speaker for providing audible output.

13. A support evaluation device as claimed in any preceding claim, in which the output means includes one or more LEDs for providing visual output.

14. A support evaluation device as claimed in any preceding claim, in which the output means includes a signal for communication with an external device.

15. A support evaluation device as claimed in any preceding claim, incorporated into a cushion or a seat.

16. A kit comprising a support evaluation device as claimed in any of claims 1 to 15, and at least first and second pressure monitoring cushions, the first cushion having a predetermined cushion strength corresponding to the first pressure band of the support evaluation device, and the second cushion having a predetermined cushion strength corresponding to the second pressure band of the support evaluation device.

17. A support evaluation device comprising at least one pressure sensor, output means linked to the pressure sensor for indicating signals therefrom, and a power source, the or each pressure sensor including first and second electrical conductors, and an insulator spacing the electrical conductors, the or each pressure sensor has a capacitance in an uncompressed state and a different capacitance in a compressed state, and the controller is adapted to measure pressure sensor capacitance, triggering an output from the output means if the measured capacitance of the or each pressure sensor when compressed remains substantially unchanged for a predetermined period of time.

18. A support evaluation device as claimed in claim 17, in which the controller can derive the pressure applied to the or each pressure sensor from the measured capacitance value(s).

19. A support evaluation device as claimed in claim 17 or 18, in which the controller is programmable with one or more custom capacitance thresholds per pressure sensor.

20. A support evaluation device as claimed in any of claims 17 to 19, in which a plurality of pressure sensors is provided in different parts of the device, at or near the surface of the device.

21. A support evaluation device as claimed in claim 20, in which the plurality of sensors operates in parallel.

22. A support evaluation device as claimed in any of claims 17 to 21, in which two or more pressure sensors are provided in series in a stack in the device.

23. A support evaluation device as claimed in any of claims 17 to 22, in which the insulator is resilient and made of foam.

24. A support evaluation device as claimed in any of claims 17 to 23, in which the insulator is made of combustion modified high resilience (CMHR) foam.

25. A support evaluation device as claimed in any of claims 17 to 24, in which each electrical conductor includes a carbon-printed surface.

26. A support evaluation device as claimed in any of claims 17 to 25, in which each electrical conductor includes carbon-printed polythene.

27. A support evaluation device as claimed in any of claims 17 to 26, in which the output means includes a speaker for providing audible output.

28. A support evaluation device as claimed in any of claims 17 to 27, in which the output means includes one or more LEDs for providing visual output.

29. A support evaluation device as claimed in any of claims 17 to 28, in which the output means includes a signal for communication with an external device.

30. A support evaluation device as claimed in any of claims 17 to 29, incorporated into a cushion or a seat.

31. A support evaluation device substantially as described herein, with reference to and as illustrated in FIGS. 1 to 3 of the accompanying drawings.

32. A support evaluation device substantially as described herein, with reference to and as illustrated in FIG. 4 of the accompanying drawings.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0052] For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made by way of example only to the accompanying drawings, in which:

[0053] FIG. 1 shows an exploded perspective view of a first embodiment of a support evaluation device;

[0054] FIG. 2 shows a partial side cross-sectional view through the device of FIG. 1;

[0055] FIG. 3 shows a side cross-sectional view of the device of FIG. 1 in use, with a person seated atop the device; and

[0056] FIG. 4 shows a side cross-sectional view of a second embodiment of a support evaluation device in use, with a person seated atop the device.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0057] Referring firstly to FIG. 1, a first embodiment of a support evaluation device is indicated generally at 10. The device 10 is a cushion including a top cushion 12 and a bottom cushion 14. Each cushion 12, 14 includes a sheet of foam. The foam is resilient and can be compressed. A stack 16 of pressure sensors is disposed between the cushions 12, 14. The cushions 12, 14 are each 10 mm thick in this embodiment. Each pressure sensor has an area of approximately the same size and shape. The pressure sensors are disposed coaxially through the stack 16.

[0058] The stack 16 includes a first pressure sensor consisting of electrically conductive sheets (or layers) 18, 20 on either side of a foam layer (or sheet) 22. In this embodiment, the foam layer in the first pressure sensor is 5 mm thick. The stack 16 also includes a second pressure sensor consisting of electrically conductive sheets 20, 24 on either side of a secondary foam layer 26. The stack 16 also includes a third pressure sensor consisting of electrically conductive sheets 24, 28 on either side of a tertiary foam layer 30. The secondary and tertiary foam layers are each 10 mm thick in this embodiment. The foam layers 22, 26, 30 are electrically insulating. Each foam layer 22, 26, 30 is resilient and compressible.

[0059] The pressure sensors are arranged in layers or tiers within the stack 16. The layers are substantially parallel. Each pressure sensor lies in a different horizontal plane of the stack. In other words, the pressure sensors lie on top of one another. The conductive sheets 18, 20, 24, 28 and foam layers 22, 26, 30 alternate within the stack, concatenating the pressure sensors. Each pressure sensor functions as a pressure switch. Higher pressures are needed to operate pressure sensors disposed lower down in the stack. This is because more material must be deformed to bring the corresponding conductive sheets into contact.

[0060] The foam layers 22, 26, 30 and cushions 12, 14 in this embodiment are all 50/230 grade foam. Additionally, the foam layers 22, 26, 30 and cushions 12, 14 are combustion modified high resilience (CMHR) foam. Each foam layer 22, 26, 30 is a spacer between the conductive sheets 18, 20, 24, 28. The foam layers 22, 26, 30 each include a plurality of apertures or holes 22a, 26a, 30a. The axes of each aperture 22a, 26a, 30a runs approximately in line with the length of the stack 16. The apertures 22a, 26a, 30a are arranged in rows extending from one side to the other of the respective foam layers 22, 26, 30. The apertures 22a, 26a, 30a may be arranged regularly or irregularly in other embodiments.

[0061] The apertures 22a, 26a, 30a in each foam layer 22, 26, 30 are co-aligned. The foam layers 22, 26, 30 are compressed when the device 10 is sat upon, but the apertures 22a, 26a, 30a substantially retain their size, shape and relative spacing. The conductive sheets 18, 20, 24, 28 cover the apertures 22a, 26a, 30a on the sides of the respective foam layers 22, 26, 30. In other embodiments, the apertures in different foam layers may be anti-aligned, or have another alignment.

[0062] The conductive sheets 18, 20, 24, 28 are each carbon-printed (or carbon-coated) sheets of polythene. Polythene is durable and can undergo deformation through the relevant apertures in the foam layers 22, 26, 30 over many cycles without wearing out. Using carbon as a conductor is better than metal because it is lighter, it will not undergo metal fatigue during repeated compression cycles. Additionally, internal arcing across air gaps will not occur if a small gap is present between a pair of conductive sheets.

[0063] The first, second and third pressure sensors function in series within the stack. The first pressure sensor is uppermost in the stack 16. The first and second pressure sensors are adjacent and share a common conductive sheet 20. Operation of the second pressure sensor is conditional on operation of the first pressure sensor. The second and third pressure sensors are adjacent and also share a common conductive sheet 24. The common conductive sheets each form an interface between respective foam layers. Operation of the third pressure sensor is contingent on operation of the first and second pressure sensors. Note that other embodiments may instead have distinct conductive sheets for each pressure sensor, which may be separated by an insulating layer.

[0064] By using three pressure sensors, pressure falling within four different pressure bands can be measured or detected using the device 10. At an applied pressure of less than around 80 mmHg, none of the pressure sensors are brought into operation. At a pressure threshold of around 80 mmHg, the first pressure sensor is activated. At a second pressure threshold of around 130 mmHg. At a third pressure threshold of around 170 mmHg, the third pressure sensor is activated. At an applied pressure above around 170 mmHg, all three of the pressure sensors are brought into operation.

[0065] From the above pressure thresholds, the four pressure bands correspond to pressure in the following ranges: less than around 80 mmHg, between around 80-130 mmHg, between around 130-170 mmHg, and above around 170 mmHg. Support cushions may be provided to provide incrementally firmer support corresponding to the successively higher pressure bands.

[0066] Each of the pressure sensors can be brought into operation under sufficient pressure. This is because, in use, the foam layers compress into a significantly smaller volume where the applied pressure is highest, shortening the distance the conductive sheets must bridge to make electrical contact through the foam layer. This allows detection of the highest pressure at any single point on the device 10, and hence any part of the person seated on the device. In other words, the device 10 provides a continuous sensing region or area, rather than being limited to individual sensor inputs located in discrete areas.

[0067] An output assembly 32 is provided at the side of the device 10. The output assembly is connected to each of the conductive sheets 18, 20, 24, 28 by electrical wires. The output assembly 32 includes three LEDs 34a, 34b, 34c. The output assembly also includes a battery for powering the LEDs and pressure sensors. The output assembly includes a controller (not shown) programmed to control the LEDs 34a, 34b, 34c according to input signals received from the pressure sensors. Together, the controller, the conductive sheets 18, 20, 24, 28, the LEDs 34a, 34b, 34c and the battery form parts of an electrical circuit.

[0068] In this embodiment, the controller controls the LEDs in the following manner. The first LED 34a is lit when the conductive sheets 18, 20 of the first pressure sensor connect. The second LED 34b is lit when the conductive sheets 20, 24 of the second pressure sensor connect. The third LED 34c is lit when the conductive sheets 24, 28 of the third pressure sensor connect. In alternative embodiments, the LEDs may flash or light concurrently, for example, depending on the pressure applied to the device 10 in use. It will be appreciated that the LEDs could be normally on, and individually deactivate to signal connection of the respective conductive sheets, for example.

[0069] In this embodiment, the LEDs 34a, 34b, 34c are green, amber and red. The green LED indicates the first pressure sensor is in operation. The amber LED indicates the second pressure sensor is in operation. The red LED indicates the third pressure sensor is in operation. This provides a visual cue regarding the strength of support cushion to be prescribed for a patient.

[0070] The foam layers 22, 26, 30 also each include a side cut-out or recess 22b, 26b, 30b. When assembled, the output assembly 32 fits into these recesses 22b, 26b, 30b so that it does not protrude from the side of the device 10.

[0071] Referring now to FIGS. 2 and 3, the device can be seen before and during use by a person 100 respectively. It can be seen that the foam layers 22, 26 in the first and second pressure sensors are substantially collapsed beneath the person 100 in FIG. 3, and the respective conductive sheets 18, 20, 24 come into contact. This signals the controller to light the LEDs 34a, 34b corresponding to those pressure sensors. The foam layer 30 in the third pressure sensor is not collapsed, and so the corresponding LED 34c is not lit. The device 10 therefore indicates that a cushion corresponding to support for pressure in the range 130-170 mmHg is appropriate for the person 100.

[0072] In use, it is envisaged that the device 10 will be used as part of a clinical assessment of a patient who spends significant amounts of time sitting or lying down. The device 10 may be provided integrated into (i.e. built into) a cushion of a chair, for example, and may be provided with a removable washable cover.

[0073] When a patient is sat atop the device 10, the pressure exerted on the device causes the uppermost conductive sheet 18 to enter one or more of the apertures 22a in the uppermost foam layer 22. Over time, depending on the pressure applied, other conductive sheets may also come into contact in either the second or the second and third pressure sensors beneath the first pressure sensor. This activates the LEDs 34a, 34b, 34c corresponding to the operational/active pressure sensors. In turn, this enables prescription of a cushion capable of providing support appropriate to the highest pressure band measured by the pressure sensors.

[0074] Referring now to FIG. 4, a second embodiment of the support evaluation device is indicated generally at 110. The device 110 is a cushion and includes a top cushioned layer 112 and a bottom cushioned layer 114. Each layer 112, 114 includes a sheet of foam which is compressible and resilient. A pressure sensor layer 116 is disposed between the cushioned layers 112, 114. The cushioned layers 112, 114 are each 10 mm thick in this embodiment.

[0075] The pressure sensor includes two electrically conductive sheets (or layers) 118, 120 on either side of a foam layer (or sheet) 122. The foam layer is electrically insulating, resilient and compressible. The other features of the sensor 116 are similar to those of the first embodiment, except that apertures are not provided through the insulating foam layer 122.

[0076] An output assembly 132 is provided at the side of the device 110. The output assembly is connected to each of the conductive sheets 118, 120 by electrical wires. The output assembly 132 includes three LEDs 134a, 134b, 134c. The output assembly 132 also includes a battery (not shown) for powering the LEDs 134a, 134b, 134c and pressure sensor 116. The output assembly 132 further includes a controller (not shown) programmed to control the LEDs 134a, 134b, 134c according to input signals received from the pressure sensor 116.

[0077] The controller is programmed to measure the capacitance of the pressure sensor 116. When the person 100 has sat on the cushion, depressions corresponding to the ischial tuberosities are formed in the device 110. This causes the capacitance of the cushion to change. The controller measures and records the initial (uncompressed) and final (compressed) values as signals from the pressure sensor 116.

[0078] The controller can determine the pressure being exerted on the cushion 110 based on the capacitance change, relative to its initial value. This also works if the initial state is another compressed state. This information is used to light up the appropriate LED (or LEDs) 134a, 134b, 134c to indicate the firmness of another cushion to be prescribed. A speaker may be used in another embodiment of the capacitive support evaluation device.

[0079] Other embodiments are envisaged within the scope of the claims. For example, a similar cushion to the first embodiment may be provided with capacitive pressure sensors, without apertures through the insulators, and the controller is adapted to measure the capacitance of each sensor. Alternatively, there may not be a controller for the output means, if contact between the conductive sheets is used to directly initiate output. Wires in the capacitive version may be connected across a plurality of points in the or each pressure sensor, allowing a series of capacitance/pressure measurements to be taken to distinguish regions of different pressure for different parts of the body. This could be an alternative or additional feature to having a plurality of sensors operating in parallel.

[0080] One or more speakers may be provided instead of or in addition to the LEDs. The speakers could output different tones to indicate the pressure bands measured during use. A signal (possibly wireless) could be sent to an external system, such as a hospital records system, to record the results of a patient using the evaluation device for future reference. The device may be incorporated into a mattress or bed, for evaluating support across the whole of a person's body. A combination of pressure sensors, some have apertures through the insulators and some being capacitive, may be provided. The weight of the person sitting on the device may be a power source for powering the output, for example.

[0081] The embodiments described above are provided by way of example only, and various changes and modifications will be apparent to persons skilled in the art without departing from the scope of the present invention as defined by the appended claims.