Motion Tracking System for Robust Non-Contact Blood Perfusion Sensor

Circular pyramidal kirigami microscanner with millimeter-range low-power lens drive

This paper proposes an electrothermally-actuated circular pyramidal kirigami microscanner with a millimeter-range low-power lens drive for endoscopic biomedical applications. A variation of Japanese origami art, kirigami involves creation of out-of-plane structures by paper cutting and folding. The proposed microscanner is composed of freestanding kirigami film on which the spiral-curved thermal bimorphs are strategically placed. The kirigami microscanner is electrothermally transformed into an out-of-plane circular multistep pyramid by Joule heating. The circular pyramidal kirigami microscanner on a small footprint of 4.5 mm × 4.5 mm was fabricated by microelectromechanical system processes. A large four-step pyramidal actuation was successfully demonstrated, and a large 1.1-mm lens travel range at only 128 mW was achieved.

Development of a Robust Autofluorescence Lifetime Sensing Method for Use in an Endoscopic Application

Endoscopic autofluorescence lifetime imaging is a promising technique for making quantitative and non-invasive diagnoses of abnormal tissue. However, motion artifacts caused by vibration in the direction perpendicular to the tissue surface in a body makes clinical diagnosis difficult. Thus, this paper proposes a robust autofluorescence lifetime sensing technique with a lens tracking system based on a laser beam spot analysis. Our optical setup can be easily mounted on the head of an endoscope. The variation in distance between the optical system and the target surface is tracked by the change in the spot size of the laser beam captured by the camera, and the lens actuator is feedback-controlled to suppress motion artifacts. The experimental results show that, when using a lens tracking system, the standard deviation of fluorescence lifetime is dramatically reduced. Furthermore, the validity of the proposed method is experimentally confirmed by using a bio-mimicking phantom that replicates the shape, optical parameters, and chemical component distribution of the cancerous tissue.