A Novel Micro-Biopsy Actuator for Capsular Endoscope using LIGA Process

This paper presents the LiGA (a German acronym for lithographie, galvanoformung, abformung) process based microactuator to be used for microbiopsy in capsular endoscopes. This microactuator is designed to be integrated into a capsular endoscope and to extract tissue samples inside small gastrointestine which a conventional endoscope cannot reach. The proposed microactuator was fabricated as a cylindrical shape of diameter 10 mm and length 1.8 mm. This actuator consists of 3 parts: microbiopsy part with microspike, actuating part with torsion spring, and triggering part with shape memory alloy (SMA) heating wire and polymer string. In order to extract sample tissue, a micro-spike in the developed actuator moves forward and backward using slider-crank mechanism. For the low power consumption triggering, polymer-melting scheme was applied. The SMA heating wire consumed approximately 1.5 V times 160 mA times 1 sec (66.67 muWH) for triggering. The precise components of the microactuator were fabricated using the LiGA process in order to overcome the limitations in accuracy of conventional precision machining. The developed microactuator was evaluated by extracting tissue samples from small intestine of a pig ex vivo, and examining the tissue with the Hematoxylin and Eosin (H&E) staining protocol. The experimental tests demonstrated that developed microactuator with microspike successfully extracted tissue samples from the pig´s small intestines.