No abstract

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˚.

TEI successfully tracks LD in in vitro experiments based on a single US transducer and is robust to catheter/tissue contact, ablation time and even tissue heterogeneity. The presence of a TEB suggests thermal expansion as the main strain mechanism during coagulation, accompanied by compression of the adjacent non-ablated tissue. The isolation of thermally induced displacements from in vivo motion is a matter of future research. TEI is potentially applicable to other treatments such as percutaneous RFA of liver and high-intensity focused ultrasound.