EAGER: Opto-Radiometric Powered Untethered MEMS Microfliers

EARLY概念探索性研究资助（EAGER）项目建立在对无系留微型飞行器（即自由飞行的微尺度结构）的初步演示的基础上。横跨微型飞行器底盘的温度梯度驱动从热侧到冷侧的净气流，并且通过从该气流到微型飞行器主体的动量传递产生升力。这种效应被称为“辐射力”，世纪以来一直是物理学家和流体力学家研究的对象，但直到最近才开始出现全面的理解。虽然辐射力太弱，在大气压力下无法影响较大的物体，但对于特征长度小于1毫米的物体，辐射力的缩放是有利的。随着微机电系统（MEMS）制造技术的进步，激光驱动的光辐射测量微型飞行器有可能将人类控制飞行的范围推向前所未有的小型化水平。该项目将朝着这一目标前进，具有互补的理论和实验组成部分。这些结果将为一类新的航空微型机器人铺平道路，其应用包括监视，微装配，空气污染监测和空气威胁检测。尽管存在微型飞行昆虫，但航空微型机器人以前没有被研究过。热（辐射）力已被证明可以移动空气中的微米级颗粒，自1873年克鲁克斯辐射计发明以来，人们已经研究了由光吸收结构的光学加热引起的辐射力。该项目将验证实现无约束、受控光辐射测量微尺度飞行的可行性，即通过聚焦光束照射无约束微加工结构产生的热梯度推动飞行。研究团队将开发大气压下光辐射微尺度飞行的新理论，研究在不增加微型飞行器质量的情况下增加光辐射功率传输的新型材料和微制造工艺，使用微制造技术和双光子立体光刻相结合制造和测试无系留微型飞行机器人的原型，并研究获得飞行稳定性和控制的生物启发机制。

This EArly-concept Grant for Exploratory Research (EAGER) project builds upon preliminary demonstrations of untethered microfliers, that is, free-flying microscale structures. A temperature gradient across the microflier chassis drives a net flow of air from hot to cold side, and lift is generated by momentum transfer from this flow to the microflier body. Known as "radiometric force," this effect has been an object of study by physicists and fluid dynamicists for over a century, but only recently has a comprehensive understanding begun to emerge. Though too weak to affect larger objects at atmospheric pressures, radiometric forces scale advantageously for characteristic lengths less than a millimeter. Together with advances in fabrication of micro electro mechanical systems (MEMS), laser-driven opto-radiometric microfliers have the potential to push the envelope of human controlled flight to unprecedented levels of miniaturization. This project will advance towards that goal, with complementary theoretical and experimental components. The results will pave the way for a new class of aerial microrobots with applications such as surveillance, microassembly, airborne pollution monitoring and airborne threat detection.Despite the existence of microscale flying insects, aerial microrobots have not been previously investigated. Thermal (radiometric) forces have been shown to move micron-sized particles in air, and radiometric forces caused by optical heating of light-absorbing structures have been studied since the invention of the Crookes Radiometer in 1873. This project will validate the feasibility of achieving untethered, controlled opto-radiometric microscale flight, i.e. flight propelled by forces generated via a thermal gradient from a focused optical beam illuminating untethered microfabricated structures. The research team will develop new theory of opto-radiometric microscale flight at atmospheric pressures, investigate novel materials and microfabrication processes that increase the opto-radiometric power transfer without increasing the microflier mass, fabricate and test prototypes of untethered microscale flying robots using a combination of microfabrication technologies and 2-photon stereolithography, and investigate biologically-inspired mechanism for attaining in-flight stability and control.