An endoscopic force-position sensor grasper with minimum sensors

This study reports on the design, fabrication, testing, and mathematical modelling of a semiconductor microstrain-gauge endoscopic tactile sensor. The sensor can measure, with reasonable accuracy, the magnitude and the position of an applied load on a grasper. The designed assembly consists of two semiconductor microstrain-gauge sensors, which are positioned at the back face of a prototype endoscopic grasper. The intensity of the applied force can be seen on a light emitting diode (LED) device. Altogether, 20 different force magnitudes for seven different locations on the endoscopic grasper are tested experimentally. The magnitudes of force vary from 0.5 to 10 N with an increment of 0.5 N. The in-house electrical amplification system for the microstrain gauges is also designed, fabricated, and tested. The sensor is insulated and can operate safely in wet environments. It exhibits high force sensitivity, good linearity, and large dynamic range. To predict the behaviour of the designed system under various loading conditions, three-dimensional finite element modelling (FEM) is used. There is a good correlation between the computed theoretical results for the force magnitudes together with their points of application and the experimental results. The miniaturized electronic device could be integrated with an endoscopic grasper.