SYNTHESIS AND FABRICATION OF LASER SCRIBED NANO-COMPOSITES FOR STRAIN SENSING

Abstract

Flexible Strain sensors are an important constituent in soft robotics, health care devices and defense industry. In flexible strain sensors, achieving consistency and high sensitivity has always been challenging. A number of materials and their derivatives have been explored to achieve the ultimate balanced sensitivity and strain range. In this work we have fabricated thin film strain sensor device prepared by drop casting method. A specific intensity laser is used to draw 1 × 1 cm2 pattern on graphene oxide (GO) to convert it into reduced graphene oxide (RGO). Conversion of GO into RGO causes the material to become conductive and shows piezoresistive behavior upon applying strain. The device is fabricated on polydimethylsiloxane (PDMS) as a base material due to its flexibility and bio compatibility. It can easily stick with the human skin. A locally made test rig is used to produce the effect of torsion, bending and stretching on the strain sensor device. The resulting resistance change on the device has been measured. The sensitivity is calculated as gauge factor. The gauge factor of torsion, bending and stretching is observed to be 90.3, 3.5 and 12.1 respectively. The corresponding strain ranges are 0-11%, 0-150% and 0-140%. This sensor is found to be providing a balance between strain range and sensitivity. Hand test was performed for the detection of joint muscle movement. Change of resistance has been observed indicating the working performance of the device. A 2 × 2 pressure sensor array has also been fabricated by availing the same method. Pressure has been detected by manually exerting the pressure on this device. Change of resistance has been calculated by using multi-meter. These types of strain sensors are used for health monitoring e.g muscle motion of a diseased person, heartbeat and blood pressure measurement.

Flexible Strain sensors are an important constituent in soft robotics, health care devices and defense industry. In flexible strain sensors, achieving consistency and high sensitivity has always been challenging. A number of materials and their derivatives have been explored to achieve the ultimate balanced sensitivity and strain range. In this work we have fabricated thin film strain sensor device prepared by drop casting method. A specific intensity laser is used to draw 1 × 1 cm2 pattern on graphene oxide (GO) to convert it into reduced graphene oxide (RGO). Conversion of GO into RGO causes the material to become conductive and shows piezoresistive behavior upon applying strain. The device is fabricated on polydimethylsiloxane (PDMS) as a base material due to its flexibility and bio compatibility. It can easily stick with the human skin. A locally made test rig is used to produce the effect of torsion, bending and stretching on the strain sensor device. The resulting resistance change on the device has been measured. The sensitivity is calculated as gauge factor. The gauge factor of torsion, bending and stretching is observed to be 90.3, 3.5 and 12.1 respectively. The corresponding strain ranges are 0-11%, 0-150% and 0-140%. This sensor is found to be providing a balance between strain range and sensitivity. Hand test was performed for the detection of joint muscle movement. Change of resistance has been observed indicating the working performance of the device. A 2 × 2 pressure sensor array has also been fabricated by availing the same method. Pressure has been detected by manually exerting the pressure on this device. Change of resistance has been calculated by using multi-meter. These types of strain sensors are used for health monitoring e.g muscle motion of a diseased person, heartbeat and blood pressure measurement.