Biopsy needle tract cauterization using an embedded array of piezoceramic microheaters

This paper presents the use of an array of piezoceramic microheaters embedded in a biopsy needle for tract cauterization. Circular PZT-5A heaters of 200 ¿m diameter and 70-80 ¿m thickness are embedded in the wall of a 20-gauge stainless steel needle. Finite element modeling suggests that a PZT array with no gap between the elements to be the most suitable design. The temperature profile generated is measured at two resonance modes: the radial mode (10.3 MHz) and the thickness mode (22.3 MHz). The needle surface exceeds the minimum target temperature rise of 33°C for applied voltages of 17 V_RMS and 14 VRMS for radial and thickness mode, respectively. The corresponding input powers are 236 mW and 325 mW, respectively. The tissue cauterization extends 1-1.25 mm beyond the perimeter of needle.