A steerable smart catheter tip realized by flexible hydrogel actuator

This paper reports the first smart catheter tip realized by integrating a thermoresponsive hydrogel on a flexible strip of microfabricated heater, targeting at applications in minimally invasive vascular treatments and other surgical procedures. A bimorph-like active tip structure is fabricated by integrating a 500-μm-thick layer of poly(N-isopropylacrylamide) hydrogel on top of the 20-mm-long region of a 3.5-mm-wide flexible polyimide strip that embeds a micropatterned resistive heater. The activation of the heater stimulates the hydrogel layer to shrink and bend the flexible tip, providing the catheter with controlled steering ability for a wide range of navigation angles. Infrared imaging shows uniform heating over the entire hydrogel region within a ~2-°C variation. The fabricated prototypes are assembled on commercial catheter tubes and operated to demonstrate bending angles of up to 130°, which is significantly larger compared with other active catheters reported. Dynamic characterization of the device also shows promising results towards the target application.