Pressure sensor - Voltage measuring from a pressure sensitive thin films

Thread Starter

arulkashmir

Joined May 25, 2018
1
Hi friends,
I am a Chemist. Very recently I started to work on pressure sensors. I have a two-electrode pressure sensitive device, which will be generating voltage changes upon applying pressure. So far I have been using multimeter to monitor the voltage change upon applying pressure. But, now I would like to make a portable pressure sensor module. For that, I need to make my own voltage reading unit PCBs which can measure the voltage output from my pressure sensitive parallel plate two electrode piezoelectric device. Please kindly bear with me because I am zero in electronics. If someone help me to understand how to design a PCBs circuits and component choice... I will be highly gratified...
 

danadak

Joined Mar 10, 2018
3,605
Typically transducers like his implemented in a bridge configuration.

That in turn requires a good differential amplifier to eliminate common mode
unwanted noise. Instrumentation Amplifier, IA for short. Also helps if shielded
cables used between transducer and signal conditioning circuits.

More advanced sensor processing can use processors, and there exist ones
with analog and A/D conversion that make life easy. Even high precision
differential inputs which help with the Common Mode problem. And DSP to
do advanced filtering.



The A/D in pic configed as 8 bit, actually goes to 20 bits.

More than you want to know about IAs -

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0ahUKEwj_w7-_7KDbAhVM3IMKHco6BQcQFgg4MAE&url=http://www.analog.com/media/en/training-seminars/design-handbooks/designers-guide-instrument-amps-complete.pdf&usg=AOvVaw1sSxTBpXd1697BmJ1D0uNS


Regards, Dana.
 
Last edited:

Picbuster

Joined Dec 2, 2013
979
Hi friends,
I am a Chemist. Very recently I started to work on pressure sensors. I have a two-electrode pressure sensitive device, which will be generating voltage changes upon applying pressure. So far I have been using multimeter to monitor the voltage change upon applying pressure. But, now I would like to make a portable pressure sensor module. For that, I need to make my own voltage reading unit PCBs which can measure the voltage output from my pressure sensitive parallel plate two electrode piezoelectric device. Please kindly bear with me because I am zero in electronics. If someone help me to understand how to design a PCBs circuits and component choice... I will be highly gratified...
There are many examples in schematic and programming available from Microchip.
Your sensors loads are probably slow (changing in seconds not in milli or micro seconds)
Resulting in simple filters ,software and hw design
Look at the Pic18f87k22 (12bit ADC on board). (sample HW and software available excellent for the starter in electronics)

Picbuster
 

KMoffett

Joined Dec 19, 2007
2,770
danadak,
"pressure sensitive parallel plate two electrode piezoelectric device"
The output from piezoelectric sensors is a voltage. A bridge is for resistive sensors.

arulkashmir,
What are you getting for a range of output voltages from you sensor?

Ken
 

danadak

Joined Mar 10, 2018
3,605
The output from piezoelectric sensors is a voltage. A bridge is for resistive sensors.
Excellent comment on my oversight. However bridges are, in a general sense,
good for impedance measurement, not just resistive.

The prior solution post with diff ADC would still apply. Single ended or differential.

Regards, Dana.
 
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