Novel Integrated System Architecture for an Autonomous Jumping Micro-Robot

As the capability and complexity of robotic platforms continue to evolve from the macro to micro-scale, innovation of such systems is driven by the notion that a robot must be able to sense, think, and act [1]. The traditional architecture of a robotic platform consists of a structural layer upon which, actuators, controls, power, and communication modules are integrated for optimal system performance. The structural layer, for many micro-scale platforms, has commonly been implemented using a silicon die, thus leading to robotic platforms referred to as "walking chips" [2]. In this thesis, the first-ever jumping microrobotic platform is demonstrated using a hybrid integration approach to assemble on-board sensing and power directly onto a polymer chassis. The microrobot detects a change in light intensity and ignites 0.21mg of integrated nanoporous energetic silicon, resulting in 246µJ of kinetic energy and a vertical jump height of 8cm

Investigating Energetic Porous Silicon as a Solid Propellant Micro-Thruster

Energetic porous silicon has emerged as a novel on-chip energetic material capable of generating thrust that can be harnessed for positioning of millimeter and micron-scale mobile platforms such as microrobots and nano-satellites. Porous silicon becomes reactive when nano-scale pores are infused with an oxidizer such as sodium perchlorate. In this work, energetic porous silicon was investigated as a means of propulsion by quantifying thrust and impulse produced during the exothermic reaction as a function of porosity. The baseline porous silicon devices were two millimeter diameter and etched to a target depth of 25 microns. As a result of changing porosity, a 7x increase in thrust performance and a 16x increase in impulse performance was demonstrated. The highest thrust and impulse values measured were 680 mN and 266 micron Newton seconds respectively from a 2 mm diameter porous silicon device with 72 % porosity. Limitations and trade-offs associated with arrays of devices were presented by studying the effects of scaling porous silicon area, and characterizing thrust when arrays of porous silicon micro-thruster devices were ignited simultaneously. In addition, the effects of sympathetic ignition were evaluated to better understand how closely independent devices could be physically spaced on a 1 cm2 chip. 3D nozzles were fabricated to study confinement effects by varying nozzle throat diameter, and divergent angle. It was shown that integration of a nozzle (throat diameter of 0.75 mm and a divergent angle of theta = 10 degrees) resulted in approximately 4X increase in thrust, and 4X increase in impulse. This study highlighted enhancements to thrust and impulse generated by porous silicon, identified trade-offs associated with simultaneous activation of multiple devices on a 1 cm2 chip, and showed energetic porous silicon as a viable solid propellant for propulsion of nano-satellites and micro-robots