Miniature tri-axial force sensor for feedback in minimally invasive surgery

A miniature tri-axial force sensor has been developed that complies with the requirements of integration into biomedical and robotic devices due to its size and accuracy. The sensor is a machined Titanium alloy body of the overall dimensions 8.6 × Ø3.4 mm with semi-conductor strain gauges embedded on it. The sensing beam's size is 1 × 1 × 4.4 mm. We present here the design, calibration method and performance evaluation of our sensor. Properly calibrated, it can provide absolute resolution of 5 mN at 2 N full scale. The accuracy of the estimated angle of incidence is ±1°. The measured magnitude of the force is within the ±4% range of the actual one. At maximal load the accuracy of the shear angle is ±1°.