Force sensing data spikes error

Other Hardware Sensors
1

Hi,

I'm linking 7 force sensitive sensors (Teskscan sensor) to Arduino nano for measuring foot pressure at 50Hz, but eventually ideally to 100Hz, with the non inverting op amp circuit below (it shows one sensor connection), because of the different sensing range, I use different resistors for each sensor connecting the the op amp. But typically I always get problems with the the red curve in image A, it shows a sudden spike in between two normal peaks, that happens quite a lot especially when I walked for a long time. I'm suspecting if that is the op amp problem or the capacitor. (not sure spikes from image A and C are resulted from the same problem) could anyone advice?

For the sensor data, x-axis is time in millisecond,
image sensor data A shows data of 7 sensors;
image sensor data B shows data of just one sensor (which is the red curve in the image A)
image sensor data C is the zoomed in version of image B

sensor data B.png
sensor data B.png1920×1080 108 KB

sensor data C.png
sensor data C.png1920×1080 110 KB

sensor data A.png
sensor data A.png1021×997 126 KB

2

Sorry just found out the circuit image is not attached.

circuit.png
circuit.png1274×1125 218 KB

3

Where's the decoupling on the inverting input? Or the Opamp supplies?
Add a resistor between the opamp and Arduino, the opamp is running above the Arduino's voltage so you must
protect it. Suggest 4k7 or so.

Could be noise pickup given the lack of decoupling.

4

Double check your wiring for loose connections or shorts.

5

I will check for the connection and the decoupling issues then. Thank you!

For decoupling, as I'm pretty new on electronics, MarkT, could you explain a little bit? Since I have searched around, and just found decoupling with capacitor. Hope you could give me some hints on that. Thanks