Acoustically powered micro-sonobots for enhanced fluorescence biodetection

Abstract

Artificially synthesized self-powered micro/nanorobots have evolved greatly based on the established micro/nano-fabrication technology. However, micro/nanorobots in multiple practical applications including biosensing, environmental governance, and drug delivery are still limited by their moving agility and biocompatibility. Here, we present an acoustically actuated microrobot fabricated by electrochemical deposition using 3, 4- ethylenedioxythiophene (PEDOT) and SiO2 as the basic materials, called PEDOT/SiO2 micro-sonobot. The proposed microrobot has a creative structure design of a tubular body with a conical inner space for trapping microbubbles, which helps to achieve an ultra-high moving speed. The streaming generated by the resonant microbubble propels the PEDOT/SiO2 micro-sonobot at a maximum speed of 1800 times body length per second. The multi-mode control strategy is attractive in manipulating the PEDOT/SiO2 micro-sonobot to trap and enrich cargos, providing a powerful tool for nano-sized biological target detection. Facilitated by the streaming induced by resonant microbubble and the negative charge carried by the PEDOT/SiO2 micro-sonobots, positively charged microparticles are therefore adsorbed and trapped. Furthermore, a V-shaped reflector was introduced as a solid isolator to aggregate the micro-sonobots as well as the carried target particles towards the bottom of the reflector. At last, 500 nm Poly(lactic-co-glycolic acid)(PLGA) fluorescent particles are selected to demonstrate the enhanced fluorescence biodetection using the multifunctional micro-sonobots. Featured with the capability of rapid locomotion, electrostatic attraction and on-demand aggregation, the proposed PEDOT/SiO2 micro-sonobot paves a new way for enhancing fluorescent biodetection signals in an active and fast manner.