AN IN-SHOE COMPLIANCE MONITOR FOR THERAPEUTIC FOOTWEAR
FIGURE 2. AN FSR POSITIONED ON THE UNDERSIDE OF A
SHOE INSOLE FOR EXPERIMENTAL TESTING.
Figure 1 shows the FSR and Figure 2 shows the sample and digitize sensor voltages, process the
location of an FSR on the underside of a shoe insole samples, store the results in non-volatile memory,
for experimentation purposes. We monitored the and receive commands and send out data upon
voltage output of a typical FSR sensor circuit versus request. The microcontroller also can use its digital
time for the FSR positioned in the shoe as in Figure input-output ports to turn on and off power to other
2 for several persons walking for 1 min., standing for devices or circuits and to receive digital inputs from
1 min., sitting with feet flat on the floor for 1 min., other devices.
sitting with legs outstretched and heels on the floor
for 1 min., and sitting with legs outstretched and
6. NEXT STEPS
heels resting up on a stool for 1 min. As hoped, we
found that the FSR circuit output can be used to The next steps are to integrate and fully test the
distinguish different conditions of shoe usage and combined in-shoe hardware and software and to
subject activity. develop the most appropriate package for the in-shoe
5.3. MICROCONTROLLER
components for patient comfort and robustness,
including allowing the clinician to place the sensor
wherever desired. Also needed is to develop the
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The heart of the compliance monitor is an cable interface for communicating between the
integrated circuit chip called a microcontroller. A in-shoe monitor and a PC. This interface must
microcontroller is a miniature computer that can supply an appropriate level of power to the in-shoe
Pedorthic Footcare Association www.pedorthics.org