Microchannel based Flexible Dynamic Strain Sensor

The dynamic measurement of strain is needed in several applications where frequent bending is experienced. For example, in the case of robotics and prosthesis, the strain sensors could indicate the bending of fingers or hand joints [1] , [2] . Likewise, it is needed to detect the damages to interconnects due to frequent bending in the flexible and wearable electronics [3] - [5] . To this end, microchannel based technology can provide an efficient solution. This paper presents a flexible microfluidic channel-based sensor for the detection of dynamic strain. The sensor has been developed using Polydimethylsiloxane (PDMS). The micro-channel (dia~175 pm), fabricated using replica molding technique, was made conductive by filling with poly (3.4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT: PSS) polymer. The developed strain sensor was subjected to various strains, which led to changes in the channel diameter and hence the resistance. We observed about 3 order (Δ R / R ~2800) increase in the resistance ( R ) value for 10% applied strain (Δ L / L. L = length of sensor) This lead to a gauge factor (GF= (Δ R / R )/(Δ L / L )) of ~280 for 10% applied strain, which is better (~70 times) than reported polymer based strain sensors [6] - [9] .