Advances in Fiber‐Optic Technology for Point‐of‐Care Diagnosis and In Vivo Biosensing

Shawana Tabassum, and Ratnesh Kumar

Development of reliable, sensitive, selective, and miniaturized sensing technologies is critical for health assessment and early diagnosis and treatment of diseases/anomalies while simultaneously mitigating the challenges associated with in vivo measurements. Some critical constraints to the realization of in vivo measurements include the necessity to fabricate the sensor on a tightly constrained footprint while ensuring acceptable biocompatibility, accuracy, and reliability. The inherent light‐guiding properties of optical fibers over long distances, their microscopic cross‐section that can be structured at the nanoscale to manipulate the light transmittance/reflectance spectrum, excellent biocompatibility enabling their efficient integration with biorecognition molecules, immunity to electromagnetic interference, mechanical flexibility, and low cost have been inviting research attention to utilize these unique features for in vivo and label‐free point‐of‐care diagnostics. Hence, fiber‐optic biosensing has become a promising research thrust, with a plethora of emerging methodologies to develop ultrasensitive and selective sensing probes. A unified presentation of the research trends on biosensors incorporated into optical fibers is presented.

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Laser Controlled 65 Micrometer Long Microrobot Made of Ni‐Ti Shape Memory Alloy

Min‐Soo Kim Hyun‐Taek Lee Sung‐Hoon Ahn
Microrobotics has many potential applications, such as environmental remediation, in the biomedical arena. However, existing microrobots exhibit practical limitations including inadequate biocompatibility and imprecise control. Here, a microrobot made of shape memory alloy (SMA) actuator which can be driven by laser scanning to perform microscale motions is introduced. The 65 µm long microrobot having crawling‐like motion can demonstrate the movement with 10.0 µm s−1 of the maximum speed. The microrobot is controlled by a laser affording wireless, spatiotemporally selective capabilities. During actuation, the robot exhibits crawling‐like motions including trigger via the SMA as removal of adhesion to surface, propulsion induced by optothermal and optical trapping effects. Both theoretical predictions and experimental results confirm that the SMA microrobot can be actuated and controlled via laser scanning. The principle of SMA microrobots, and the optical actuation method, can be broadened to other applications that require deformable microscale structures suitable for mass production.

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