Apparatus and method for monitoring contact pressure between body parts and contact surfaces

• US 5,993,400 A
• Filed: 10/18/1993
• Issued: 11/30/1999
• Est. Priority Date: 05/23/1991
• Status: Expired due to Fees

• Current Assignee: Paul J. Moore Jr, Richard G. Rincoe
• Original Assignee: Paul J. Moore Jr, Richard G. Rincoe
• Inventors: Moore, Paul J. Jr., Rincoe, Richard G.
• Primary Examiner(s): Buiz, Michael
• Assistant Examiner(s): REIP, DAVID OWEN
• Application Number:
  US08/138,396
• Time in Patent Office: 2,234 Days
• Field of Search: 128/774, 128/779, 128/782, 128/748, 73/172, 73/862.04, 623/33, 623/35, 623/36, 623/66, 623/901, 364/556, 364/558, 364/413.01, 364/413.02
• US Class Current: 600/595
• CPC Class Codes: A61B 2562/0247 Pressure sensors
• CPC Class Codes: A61B 2562/046 in a matrix array
• CPC Class Codes: A61B 5/1036 Measuring load distribution, e.g. podologic studies
• CPC Class Codes: A61B 5/447 specially adapted for aiding the prevention of ulcer or pressure sore development, i.e. before the ulcer or sore has developed
• CPC Class Codes: A61B 5/6892 Mats
• CPC Class Codes: A61F 2/76 Means for assembling, fitting or testing prostheses, e.g. for measuring or balancing, e.g. alignment means
• CPC Class Codes: A61F 2/80 Sockets, e.g. of suction type
• CPC Class Codes: A61F 2002/505 using CAD-CAM techniques or NC-techniques
• CPC Class Codes: A61F 2002/7635 for measuring force, pressure or mechanical tension
• CPC Class Codes: A61F 2002/7695 Means for testing non-implantable prostheses
• CPC Class Codes: G01L 1/205 using distributed sensing elements
• CPC Class Codes: G01L 1/2256 involving digital counting
• CPC Class Codes: G01L 5/228 using tactile array force sensors

Abstract

An apparatus and method for monitoring pressure between the surface of a body part and a contact surface employ a plurality of pressure sensors disposed in a matrix array between the contact surface and the body part. The sensors produce analog force signals proportional to pressure, and a monitor receives the analog signals and produces output signals, preferably digital, having pressure data corresponding to the pressure at each sensor. A computer processor receives the output signals from the monitor to create a force profile for the sensor array. The sensors may be scanned as a read event in variety of manners, including periodic, continuous and triggered scanning. Where triggered scanning is desired, one or more switches act to initiate a read event. This monitoring apparatus and method is used, for example, to fit prosthetics, to monitor bed-ridden and wheelchair-bound patients, to reduce pain and sores caused by uneven distribution of pressure and to monitor pressure between a cast and a person. The sensors may be mounted on a single sheet or on strips for positioning along the body, and monitoring is accomplished by multiplexing and digitizing the analog force signals.

Claims

1. Apparatus adapted to monitor pressure at a plurality of locations along an exterior surface of a body part of a user to produce a force profile corresponding to a distribution of force caused by pressure of said body part against a contact surface, comprising:

(a) a plurality of pressure sensors organized in an array and adapted to be interposed between and in contact with the exterior surface of said body part and said contact surface at selected locations at which pressure is to be monitored, each of said sensors operative in response to compressive pressure between the exterior of said body part and said contact surface at its respective location to generate a force signal proportional to the pressure therebetween;

(b) monitor means in communication with the array of said sensors for receiving the force signal produced by each respective said sensor and for producing an output signal having pressure data corresponding to the pressure sensed by the respective sensor;

(c) processing means in communication with said monitor means for receiving and processing the output signals to produce the force profile defining the distribution of force corresponding to the magnitude and location of pressure exerted between the contact surface and the exterior surface of said body part, said processing means including command means for generating a read signal operative to cause said monitor means to generate said output signals and to communicate a set of said output signals correlated to each of said sensors to define a read event; and

(d) at least one switch means adapted to be positioned remotely of said processing means and in proximity to said body part, said switch means for producing a switch active signal in response to one of a plurality of events initiated by force caused by said body part acting on said switch means and indicative of specific pressure states on said body part, said monitor means operative after receipt of said read signal to initiate a read event in response to said switch active signal.

2. Apparatus according to claim 1 wherein said monitor means includes address means for addressing each of said sensors in said array with a unique address corresponding to its position in said array.

3. Apparatus according to claim 2 wherein said array is organized in a row and column format with the unique address of each sensor being represented by its row and column position.

4. Apparatus according to claim 3 wherein said monitor means consecutively communicates said output signals to said processing means upon receipt of the read signal.

5. Apparatus according to claim 1 wherein said force signals are analog force signals, said monitor means including converter means for converting said analog force signals to digital force signals.

6. Apparatus according to claim 1 wherein said sensors are supported on at least one strip of flexible substrate material that is adapted to be disposed between the contact surface and the exterior surface of said body part so that said strip conforms to the contour of the exterior surface of said body part to position each of said sensors at its selected location therealong.

7. Apparatus according to claim 6 wherein said processing means has memory means for storing the pressure data from each of said sensors during each said read event with said data being correlated to the address of each respective said sensor.

8. Apparatus according to claim 1 wherein the array of said sensors is adapted to monitor pressure between a prosthesis and a residual limb, said contact surface being a portion of said prosthesis interfacing said prosthesis to said residual limb.

9. Apparatus according to claim 1 wherein the array of said sensors is adapted to monitor pressure between said body part and a cast receiving said body part, said contact surface being a interior surface of said cast.

10. Apparatus according to claim 1 wherein the array of said sensors is adapted to monitor pressure between an article of furniture and a body, the contact surface defined by a support surface of said article of furniture and said body part being defined by a portion of the body contacting the support surface.

11. Apparatus adapted to monitor pressure at a plurality of locations along an exterior surface of a body part of a user to produce a force profile corresponding to a distribution of force caused by pressure of said body part against a contact surface, comprising:

(a) a plurality of pressure sensors supported on at least one strip of flexible substrate material and organized in an array such that each of said sensors has a coordinate address within the array, said strip and said sensors adapted to be interposed between and in contact with both the exterior surface of said body part and said contact surface at selected locations at which pressure is to be monitored, each of said sensors operative in response to pressure to generate an analog force signal proportional to the pressure between the exterior of said body part and said contact surface at its respective location;

(b) monitor means in communication with the array of said sensors for receiving the analog force signals produced by said sensors and for producing output signals having pressure data representative of the pressure sensed by said sensors, said monitor means including multiplexer circuitry adapted to select the force signal from a selected one of said sensors, an analog-to-digital converter operative to convert said analog force signals to digital force signals and a microprocessor operative to generate address signals whereby said multiplexer circuitry selects the force signal from an addressed sensor so that said converter produces a digital force signal corresponding to the addressed sensor, said monitor means operative to produce each of said output signals in response to the respective digital force signal from said converter;

(c) computer processing means in communication with said monitor means for receiving and processing the output signals to produce the force profile defining the distribution of force corresponding to the magnitude and location of pressure exerted between the contact surface and the exterior surface of said body part, said computer processing means including command means for generating a read signal operative to cause said monitor means to generate said address signals to generate said output signals and to communicate a set of said output signals correlated to each of said sensors to define a read event; and

(d) at least one switch means adapted to be positioned remotely of said computer processing means and in proximity to said body part, said switch means for producing a switch active signal in response to one of a plurality of events initiated by force caused by said body part acting on said switch means and indicative of specific pressure states on said body part, said monitor means operative after receipt of said read signal to initiate a read event in response to said switch active signal.

12. Apparatus according to claim 11 wherein said computer processing means has memory means for storing the pressure data from each of said sensors during each said read event with said data being correlated to the address of each respective said sensor and to the respective switch means.

13. Apparatus according to claim 11 wherein said sensors are supported on at least one strip of flexible substrate material that is adapted to be disposed between the contact surface and the exterior surface of said body part so that said strip conforms to the contour of the exterior surface of said body part to position each of said sensors at its selected location therealong.

14. Apparatus according to claim 13 wherein said sensors are mounted in a plurality of strips adapted to be spaced apart from one another along the exterior surface of said body part.

15. Apparatus according to claim 13 wherein said sensors are supported in a two dimensional array on a sheet of flexible substrate material that defines said strip.

16. Apparatus according to claim 11 wherein said array of sensors is organized as a matrix of rows and columns, said multiplexer circuitry having first multiplexer means for selecting a selected one of said columns and second multiplexer means for selecting a selected one on said rows.

17. A method of monitoring pressure between a prosthesis and an exterior surface of a residual limb to produce a force profile corresponding to a distribution and magnitude of force caused by pressure of said residual limb against an interface portion of the prosthesis interfacing said prosthesis and said residual limb when said prosthesis contacts a support surface, comprising the steps of:

(a) interposing a plurality of pressure sensors between and in contact with both the exterior surface of said residual limb and said interface portion of said prosthesis at selected locations, each of said sensors operative in response to compressive pressure between the exterior of said residual limb and said interface portion of said prosthesis at its respective location to generate a force signal proportional to the pressure therebetween;

(b) monitoring the force signals to produce an output signal in response to each force signal having pressure data corresponding to the pressure sensed by the respective sensor wherein the step of monitoring said sensors is accomplished by executing a read event at a selected time so that an array of sensors is scanned to general said output signals;

(c) disposing at least one switch on said prosthesis for producing a switch active signal when said switch is in an active state, whereby said step of executing a read event occurs in response to said switch active signal;

(d) receiving said output signals and storing the pressure data correlated to the location of each respective sensor; and

(e) displaying said pressure date as said force profile indicating the distribution of force corresponding to the pressure and location of pressure exerted between the interface portion of said prosthesis and the exterior surface of said residual limb.

18. The method according to claim 17 wherein said sensors are positioned in an array of rows and columns along said residual limb, the step of monitoring said sensors being accomplished by scanning the sensors in each row.

19. The method according to claim 17 wherein the step of monitoring said sensors is accomplished by executing a read event at a selected time so that array of sensors is scanned to generate said output signals.

20. Apparatus adapted to monitor pressure at a plurality of locations along an exterior surface of a residual limb of a user wearing a prosthesis, said apparatus for contemporaneously producing a force profile when said prosthesis contacts a support surface, said force profile corresponding to a distribution of force caused by pressure of said limb against a contact surface of said prosthesis, comprising:

(a) a plurality of pressure sensors organized in an array such that said sensors may be interposed between the exterior surface of said residual limb and said contact surface at selected locations at which pressure is to be monitored, each of said sensors operative in response to pressure between the exterior surface of said residual limb and said contact surface at its respective location to generate a force signal proportional to the pressure therebetween;

(b) monitor means in communication with the array of said sensors for receiving the force signal produced by each respective said sensor and for producing an output signal having pressure data corresponding to the pressure sensed by the respective said sensor;

(c) processing means in communication with said monitor means for receiving and processing said output signals to produce the force profile corresponding to the magnitude and location of pressure exerted by the contact surface on the exterior surface of said residual limb, said processing means including common means for generating a read signal operative to cause said monitor means to generate said output signals and to communicate a set of said output signals correlated to each of said sensors to define a read event; and

(d) a switch disposed on a portion of said prosthesis, said switch for producing a switch active signal in response to contact of said portion against the support surface which contact is caused by an event initiated by said residual limb exerting a force on said switch and indicative of a specific pressure state of said residual limb, said monitor means operative after receipt of said read signal to initiate a read event in response to said switch active signal.

21. Apparatus according to claim 20 including a plurality of switches disposed at different switch locations on said portion of said prosthesis, each of said plurality of switches for producing a switch active signal in response to contact of said lower foot portion at its respective switch location against the support surface, said monitoring means thereby operative to initiate a separate read event in response to each said switch active signal.