Acoustic Propulsion in Liquid and Air

本研究探讨微机器人在液体和空气中的声学推进，在没有机械发动机或螺旋桨的情况下，仅用电信号和电力驱动，导航到目的地。本研究是基于液体中声流效应使液体射流从聚焦超声换能器中射出，引起换能器在液体中运动的前期工作。在空气中，通过孔的合成空气射流已经被示出为在射流的相反方向上移动换能器。本文将研究液体和空气中声推进的基本原理和机理。将探索各种基于微机电系统（MEMS）的螺旋桨，具有高效率和方向性。在空气和液体中进行声学推进研究的新奇在于，它不需要移动部件、热量、可听声音或燃料燃烧，并且对环境非常友好。研究的成功结果将产生一个超小型电力推进装置（包括驱动电子设备），可以在空气和液体中分别产生10：1和40：1的推力比。因此，这项研究将极大地影响微型机器人和植入式设备的推进技术。该研究还将为如何在40 kHz至900 MHz的宽频率范围内使用MEMS压电换能器和超小型电子器件产生强大的超声波提供新的见解。来自代表性不足群体的学生将被积极招募，并有机会参与拟议的研究。高中生将参与声学螺旋桨的设计和实验。该研究旨在探索各种基于MEMS的声换能器，用于在宽频率范围（空气中40 - 500 kHz，液体中0.5 - 900 MHz）内在空气和液体中产生超声。随着换能器的设计和微制造，换能器的声强度和它们的场模式将被模拟和测量。为了确保大的声音输出和控制推进方向性，换能器将在其谐振频率下工作，并将探索和开发新的聚焦技术。拟议研究的最终目标是为液体和空气中的微型机器人开发基于MEMS的无线和电池供电的声学推进系统。将探讨用于处理换能器和相关部件的各种微加工技术。将开发带有传感器和电子设备的原型装置，并将研究推进系统单位重量（或体积）推力的基本限制和推力方向的精确控制。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This research explores acoustic propulsion of microrobots in liquid and air, to navigate to destinations without mechanical engine or propeller and driven only with electrical signal and power. This research is based on the preliminary work that in liquid, acoustic streaming effect makes liquid jet be shot out from a focused ultrasonic transducer, causing the transducer to move in liquid. In air, synthetic air jet through an orifice has been shown to move the transducer in the opposite direction of the jet flow. Here the fundamental principles and underlying mechanisms in acoustic propulsion in liquid and air will be studied. Various microelectromechanical systems (MEMS) based propellers with high efficiency and directionality will be explored. The novelty of the proposed research of acoustic propulsion in air and liquid is that it does not require moving parts, heat, audible sound, or combustion of fuel, and is very friendly to environment. The successful outcome of the research will result in a subminiature electric propulsion unit (including the drive electronics), that can produce thrust ratios of 10:1 and 40:1 in air and liquid, respectively. Thus, the research will greatly impact propulsion technology for microrobots and implantable devices. The research will also produce new insights on how to produce powerful ultrasound with MEMS piezoelectric transducers and sub-miniature electronics over a wide frequency range from 40 kHz to 900 MHz. Students from underrepresented groups will actively be recruited and given opportunities to be involved in the proposed research. The high school students will participate in the design and experimentation of acoustic propellers. The research is to explore various MEMS based acoustic transducers for ultrasound generation in air and liquid over a wide frequency range (40 - 500 kHz in air and 0.5 – 900 MHz in liquid). As the transducers are designed and microfabricated, the transducers’ acoustic intensities and their field patterns will be simulated and measured. To ensure large sound outputs and controlled propulsion directionality, the transducers will be operated at their resonant frequencies, and novel focusing techniques will be explored and developed. The ultimate goal of the proposed research is to develop MEMS-based, wireless and battery-powered acoustic propulsion systems for microrobots in liquid and air. Various microfabrication technologies for the processing of the transducers and associated components will be explored. Prototype units with the transducers and electronics will be developed, and fundamental limits on thrust force per unit weight (or volume) of the propulsion system and precision control of the thrust direction will be studied.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.