Design And Application Of The High Ductility Crack-based Strain Sensor Based On Strain Isolation Bridge

In recent years,with the continuous development of materials preparation and microelectronic processing technology,flexible electronic devices are gradually replacing some traditional silicon electronic devices.Flexible and wearable strain sensors have potential in diverse applications while development of strain sensors with both high stretch ability and highly sensitivity is still a grand challenge.Based on the above consideration,this paper proposes a high sensitivity and stretchable resistive strain sensor based on microcracks was fabricated using an ultra-violet/ozone（UV/O₃）)technique and a thin eco-flex film bridged the top of the microcracks in a single device,and a layer of conductive graphite powder was laid on the surface,achieved a wide detectable range of up to 123%and a large Guage factor（GF）of>1000 while ensuring long-term reliability.The sensor has the following specifics:Using commercial raw materials such as PDMS and graphite powder,the experimental process is simple and the production cost is low,at the same time,it has a shorter production cycle.The strain sensor has both the advantages of high stretch ability and high sensitivity,and can adjust the performance balance between stretch ability and sensitivity by controlling the geometric parameters of the buffer layer.A mechanical model is established to explain the advantages of the sensor composite structure,and the results are verified by the finite element analysis.The strain sensor has high stability and durability.After 5000 cycles of strain between 0 and 30%,the resistance change rate of the sensor is stable around 200 and can be restored to its initial value after release.The response time of this sensor is very short,and it can monitor the movement of various deformation under different frequencies.It has a great application in the detection of human respiration,pulse,heartbeat and other aspects.By further adjusting the density of micro-cracks,the sensitivity factor of the sensor can be increased,which has great potential in detecting human respiration,pulse and heartbeat.The method proposed in this paper can be easily extended to the combination of other conductive materials and stretchable substrates,thus pointing out a new direction for the fabrication of low-cost,large-scale flexible strain sensors.