Fish-inspired self-powered microelectromechanical flow sensor with biomimetic hydrogel cupula

Flow sensors inspired from lateral line neuromasts of cavefish have been widelyinvestigated over decades to develop artificial sensors. The design and function of thesenatural sensors have been mimicked using microelectromechanical systems (MEMS) basedsensors. However, there is more to the overall function and performance of these naturalsensors. Mimicking the morphology and material properties of specialized structures like acupula would significantly help to improve the existing designs. Toward this goal, thepaper reports development of a canal neuromast inspired piezoelectric sensor andinvestigates the role of a biomimetic cupula in influencing the performance of the sensor.The sensor was developed using microfabrication technology and tested for the detection ofthe steady-state and oscillatory flows. An artificial cupula was synthesized using a softhydrogel material and characterized for morphology and mechanical properties. Results showthat the artificial cupula had a porous structure and high mechanical strength similar tothe biological canal neuromast. Experimental results show the ability of these sensors tomeasure the steady-state flows accurately, and for oscillatory flows, an increase in thesensor output was detected in the presence of the cupula structure. This is the first timea MEMS based piezoelectric sensor is demonstrated to detect steady-state flows using theprinciple of vortex-induced vibrations. The bioinspired sensor developed in this workwould be investigated further to understand the role of the cupula structure in biologicalflow sensing mechanisms, thus contributing toward the design of highly sensitive andefficient sensors for various applications such as underwater robotics, microfluidics, andbiomedical devices