Methods and apparatuses for the detection of incontinence or other moisture, methods of fluid analysis, and multifunctional sensor systems

Abstract

One embodiment of a method of interrogating a sensor to detect the presence of moisture on an occupant support comprises the steps of A) providing a moisture responsive sensor in a surveillance zone of the occupant support, the sensor being tuned to a center frequency; B) exciting the sensor with an electromagnetic signal having a frequency approximately equal to the center frequency; C) monitoring for a center frequency response from the sensor; D) comparing the center frequency response to an expected center frequency response; and E) if the center frequency response compares favorably to an expected center frequency response, issuing a first output consistent with the favorable comparison.

We claim: 
     
         1 . A method of interrogating a sensor to detect the presence of moisture on an occupant support comprising:
 A) providing a moisture responsive sensor in a surveillance zone of the occupant support, the sensor being tuned to a center frequency;   B) exciting the sensor with an electromagnetic signal having a frequency approximately equal to the center frequency;   C) monitoring for a center frequency response from the sensor;   D) comparing the center frequency response to an expected center frequency response; and   E) if the center frequency response compares favorably to an expected center frequency response, issuing a first output consistent with the favorable comparison.   
     
     
         2 . The method of  claim 1  comprising:
 F) if the center frequency response does not compare favorably with the expected center frequency response, exciting the sensor with one or more electromagnetic test signals having test frequencies different than the center frequency and monitoring for a test frequency response at each test frequency and, if the test frequency response from the sensor compares favorably to an expected test frequency response corresponding to the test frequency, issuing a second output consistent with the favorable comparison between the test frequency response and the expected test frequency response corresponding to the test frequency; and 
 G) if the test frequency response from the sensor does not compare favorably to an expected test frequency response corresponding to the test frequency at any of the test frequencies, issuing a third output consistent with the unfavorable comparison between the test frequency response and the expected test frequency response corresponding to the test frequency. 
 
     
     
         3 . The method of  claim 2  wherein the output issued at step F is issued in response to the favorable comparison without first exciting the sensor at any other test frequencies. 
     
     
         4 . The method of  claim 2  wherein the output issued at step F in response to the favorable comparison is not issued until the sensor has been excited at at least one frequency other than the test frequency that yielded the favorable comparison. 
     
     
         5 . The method of  claim 1  wherein the electromagnetic signals are radio frequency signals. 
     
     
         6 . The method of  claim 1  wherein the sensor is an RFID sensor. 
     
     
         7 . The method of  claim 1  wherein the first output is an indication that an incontinence pad is present and no incontinence is detected. 
     
     
         8 . The method of  claim 2  wherein the second output is an indication that an incontinence pad is present and incontinence is detected and wherein the third output is an indication that an incontinence pad is absent or a fault has occurred. 
     
     
         9 . A system for detecting the presence of moisture on an occupant support comprising:
 a moisture responsive sensor in a surveillance zone of the occupant support, the sensor being tuned to a center frequency;   a transceiver adapted to excite the sensor with an electromagnetic signal having a frequency approximately equal to the center frequency and to monitor for a center frequency response from the sensor;   a processor adapted to compare the center frequency response to an expected center frequency response; and to issue a first output if the center frequency response compares favorably to an expected center frequency response.   
     
     
         10 . The system of  claim 9  wherein the processor is also adapted to respond as set forth below if the center frequency response does not compare favorably with the expected center frequency response:
 A) command the transceiver to excite the sensor with one or more electromagnetic test signals having test frequencies different than the center frequency; 
 B) compare the test frequency response to an expected test frequency response corresponding to the test frequency; and 
 C) if the test frequency response from the sensor compares favorably to an expected test frequency response corresponding to the test frequency, issuing a second output consistent with the favorable comparison between the test frequency response and the expected test frequency response corresponding to the test frequency; and 
 D) if the test frequency response from the sensor does not compare favorably to an expected test frequency response corresponding to the test frequency at any of the test frequencies, issue a message consistent with the unfavorable comparison between the test frequency response and the expected test frequency response corresponding to the test frequency. 
 
     
     
         11 . The system of  claim 9  wherein the electromagnetic signals are radio frequency signals. 
     
     
         12 . The system of  claim 9  wherein the sensor is an RFID sensor. 
     
     
         13 . The system of  claim 12  comprising an exposed sensor and a protected sensor. 
     
     
         14 . The system of  claim 9  comprising two or more sensors at least some of which are individual sensors having an antenna. 
     
     
         15 . The system of  claim 14  wherein all of the sensors are individual sensors having an antenna. 
     
     
         16 . The system of  claim 9  comprising two or more sensors at least some of which are individual antenna components of a sensor assembly. 
     
     
         17 . The system of  claim 16  wherein all of the sensors are individual antenna components of a sensor assembly. 
     
     
         18 . A method of interrogating a sensor to detect the presence of moisture on an occupant support comprising:
 A) providing a moisture responsive sensor in a surveillance zone of the occupant support, the sensor being tuned to a center frequency;   B) exciting the sensor with an electromagnetic signal having a frequency approximately equal to the center frequency;   C) monitoring for a center frequency response from the sensor;   D) calculating a rate of change based on the center frequency responses received at different times;   E) comparing the rate of change to one or more thresholds; and   F) issuing an output depending on the comparison.   
     
     
         19 . The method of  claim 18  wherein the calculated rate of change is a function of a change in RSSI over an interval of time. 
     
     
         20 . The method of  claim 19  wherein the calculated rate of change is a function of the difference between two excitation frequencies each of which produces a response having approximately equal RSSI values.