Flexible Force-sensitive Sealed Packet with Single Fluidic Chamber

Tactile sensor developments have been seen in the past years. The flexible and soft type of these sensors became popular due to their capability to ensure safe physical interactions with humans. This paper presents a flexible force-sensitive sealed packet that can detect normal force acting on its surface. Our sensor used poly(3,4 ethylenedioxythiophene):poly(styrene sulfonate) or PEDOT:PSS and liquid binder to form a conductive liquid mixture and put it inside the sealed packet of thin plastic. One notable difference between our proposed sensor and other PEDOT:PSS-based sensors is that ours is low-cost and easy to fabricate. For our data acquisition setup, we used a voltage divider circuit with a 68k ohm resistor connected to an analog pin of an Arduino Uno. We also used the DAYSENSOR’s DYZ-101 5-kg load cell to determine the amount of force applied, which served as our ground truth. The changes in resistance were compared against the force applied. Linear regression analysis was done to show the correlation between the two quantities, and its slope corresponds to the sensor’s sensitivity. We performed a repeatability analysis of the proposed sensor, although some challenges were observed since manual pressing was done. We also tested the change in sensitivity once a different material, such as cardboard, foam, and copper tape, is placed between the load cell and our proposed sensor. Our results showed that we can achieve higher sensitivity and better linearity using foam. For future works, we plan to extend this study to skin-like wearable devices and tactile sensing.