Close
0%
0%

Flex Sensor ADC Buffer Flex Module

2.54mm 4 channel voltage converter opamp and RC filter for Spectra Symbol Flex Sensors

Similar projects worth following
This board is designed to buffer to ADC and perform a 2nd order low pass filter for Spectra Symbol flex sensors. These sensors can be glued directly to flexible PCB.

This board is part of Fyber Labs Flex Module project.

Flex sensor input to ADC will be essentially DC voltage so filtering isn't critical. The buffer provides uniform impedance and somewhat linear use of the 0-3.3V ADC input for the resistance range of the sensor.

Sample 4.5" and 2.2" flex sensors required significant break-in. Resistance varies depending on amount of break-in and will likely increase with age/use until failure.

2.2" sample flex break in (2 minutes of ~1/4" circumference bend hand rolled through flex sensor).

Sample1Sample2Sample3Sample4
Initial33-33-4520-20-3929-29-34.531-31-44
During28-35-6031-36-7731-42-7932-75-115
After
40-120-18040-118-15044-88-14039-88-150

Resistance in KOhm (reverse bend, relaxed, forward bend)

So 2.2" range is around 20-150KOhm. 4.5" is 8-90KOhm.

LTSpice simulations were stepped through a sensor resistance range of 8K-180KOhm showing the response for these channels utilizing a ST TSX561 op-amp and 150KOhm/0.1uF pairs for a fc=10Hz,Q=0.5 Sallen-Key LPF variation.

Any software related will be released under BSD or MIT license. SAAS or cloud based software will be AGPL.

Creative Commons License

  • 2 × CRA06E083150KFTA Resistor Arrays / Thick Film Arrays
  • 9 × GRM155R70J222KA01D Capacitors / Ceramic
  • 1 × TSV854IQ4T or TSX564IQ4T Amplifier and Linear ICs / Operational Amplifiers

View all 4 project logs

Enjoy this project?

Share

Discussions

Similar Projects

Does this project spark your interest?

Become a member to follow this project and never miss any updates