Marangoni‐Propulsion Micro‐Robots Integrated with a Wireless Photonic Colloidal Crystal Hydrogel Sensor for Exploring the Aquatic Environment

Abstract

In nature, some insects can rapidly propel by using the Marangoni effect without employing the oscillatory movements of legs. Inspired by nature's Marangoni‐propulsion principles, various Marangoni‐propulsion untethered micro‐robots are achieved to propel with small energy storage. For practical use of Marangoni‐propulsion micro‐robots, it is required to have the intelligence to detect the external environment. However, previous Marangoni‐propulsion micro‐robots integrated with wireless micro‐scale sensors that can sense the external environment and transmit the obtained information are not achieved. Herein, Marangoni propulsion micro‐robots integrated with a wireless photonic gel sensor for exploring the aquatic environment and transmitting the environmental information are proposed. The proposed micro‐robots can propel at the water–air interface by the Marangoni effect. The integrated photonic gel sensor can sense the external stimuli and transmit the information by the color change. In this research, the responsivity of the micro‐robots is evaluated by the propulsion velocity and the response time of the photonic gel. It is shown that the propulsion velocity is changed by the outlet area. The response time decreased as the diameter of the photonic gel decreased. Finally, it is demonstrated that the photonic gel sensor can dynamically sense the external stimuli while the micro‐robots propel.