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I am currently working on a blood pressure monitoring system(for a class) and I was handed an old, non working wrist blood pressure monitor to salvage any components I could. So I tore it down, took out the air valve and air pump. There was yet another component soldered to the PCB which had a hose inlet(which led to the cuff), so I figured it must be the pressure sensor. Indeed it was, see the attached images:

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I figured it is a pressure sensitive resistor since it has only two pins, however the multimeter gave a reading exceeding 2000kOhm. I tried blowing into the inlet to simulate pressure rise, yielding no change in resistance whatsoever. From one of the attached images we can see that the two pins of the sensor were connected via some capacitors to the microcontroller. If anyone got any info on the name of this sensor, or maybe a similar one, it'd be appreciated.

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  • \$\begingroup\$ Emir, have you heard of cropping? \$\endgroup\$ – Bort May 31 '18 at 16:50
  • \$\begingroup\$ @Bort but I like the carpet ... static anyone... \$\endgroup\$ – Solar Mike May 31 '18 at 16:51
  • \$\begingroup\$ I edited the question, geez guys \$\endgroup\$ – Emir Šemšić May 31 '18 at 16:52
  • \$\begingroup\$ If the resistance seems non-reasonable then it could be a piezoelectric (strain-gauge) type device. Perhaps try to simulate pressure and measure DC volts on the u/m Ω scale. \$\endgroup\$ – Steve May 31 '18 at 16:53
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    \$\begingroup\$ Hey, it's comfy! \$\endgroup\$ – Emir Šemšić May 31 '18 at 17:11
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That is a capacitive/piezoelectric pressure sensor. The ones we use are in the 10 - 100 pF range for blood pressure.

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  • \$\begingroup\$ That could explain the 'infinite' resistance. \$\endgroup\$ – Emir Šemšić May 31 '18 at 17:03
  • \$\begingroup\$ Agreed. And not fun trying to find a replacement not knowing if its faulty. \$\endgroup\$ – T2JSplode May 31 '18 at 17:27

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