MEMS-Based Flexible Force Sensor for Tri-Axial Catheter Contact Force Measurement

Atrial fibrillation (AFib) is a significant healthcare problem caused by the uneven and rapid discharge of electrical signals from pulmonary veins (PVs). The technique of radiofrequency (RF) ablation can block these abnormal electrical signals by ablating myocardial sleeves inside PVs. Catheter contact force measurement during RF ablation can reduce the rate of AFib recurrence, since it helps to determine the effective contact of the catheter with the tissue, thereby resulting in effective power delivery for ablation. This paper presents the development of a 3-D force sensor to provide the real-time measurement of triaxial catheter contact force. The 3-D force sensor consists of a plastic cubic bead and five flexible force sensors. Each flexible force sensor was made of a PEDOT:PSS strain gauge and a polydimethylsiloxsane (PDMS) bump on a flexible PDMS substrate. Calibration results show that the fabricated sensor has a linear response in the force range required for RF ablation. To evaluate its working performance, the fabricated sensor was pressed against gelatin tissue by a micromanipulator and also integrated on a catheter tip to test it within deionized water flow. Both experiments simulated the ventricular environment and proved the validity of applying the 3-D force sensor in RF ablation.