This paper describes an active catheter with flexible polyimide-based integrated CMOS interface circuits for communication and control (C&C IC) to be used for applications in biomedicine. The active catheter has a multilink structure. Distributed micro shape memory alloy (SMA) coils are utilized as actuators for multidegree of freedom movement. The C&C IC's, which are incorporated on the links, require three common lead wires to address all the links and control the selected SMA actuators in the active catheter. An MOS transistor with large channel width is used for switching the SMA actuator. To reduce the system size and simplify the assembly work, the C&C circuit and three lead wires are fabricated on the same substrate using CMOS-compatible polyimide-based process. The outer diameter of the fabricated active catheter is approximately 2.0 mm. The fabricated active catheter has a four-link structure and six degrees of freedom of movement per one link. A simple bending model of one unit is presented and compared with the experiments. The fabricated C&C IC measures 1.0 mm×3.35 mm×0.2 mm. The link addressing and the actuator switching functions of the fabricated chip were confirmed. The minimum access time for addressing and actuating a single unit was 6.4 μs. The active catheter was actuated by the fabricated C&C IC chip with flexible interconnect leads in response to the C&C signals from the outside controller.
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