Shown here are descriptions, pictures, and videos highlighting a few research projects Craig has been involved in. A full list of his publications can be found on his Google Scholar page.
Jumping is a locomotion modality that allows microrobots to traverse terrain too difficult to walk over. The 80 milligram robot shown below1 was fabricated in a MEMS silicon-on-insulator process. The robot has an electrostatic inchworm motor etched into its 40 micrometer thick device layer silicon and uses it to store mechanical energy in a spring etched into its 550 micrometer thick silicon substrate.
The two videos below show the robot vertically jumping more than 3 millimeters in front of a piece of paper with 1mm vertical line spacing. A small flex PCB can be seen wirebonded to the robot, which contains three wire tethers that provide power and control to the robot from a microcontroller not seen in the videos. The first video is in real time, and the second video is in 1/8th real time. This design was both the highest jumping silicon microrobot fabricated using a standard process to date, as well as the first ever silicon microrobot to store energy in a substrate spring with an onboard motor and jump.
The two images at the bottom are 3D models of the fabricated robot showing how autonomous operation could be achieved by integrating the robot with a CMOS brain chip2 and CMOS solar cell chip3 using MEMS Zero Insertion Force sockets4.
Etching springs into the silicon substrate will one day allow autonomous microrobots to vertically jump more than one meter.
A video of the ionocraft5, a flying quadcopter-esque microrobot which has no moving parts and flies silently using electrohydrodynamic thrusters. Proclaimed as "the smallest flying robot ever made" by IEEE Spectrum in 2019.
A low-power MEMS microgripper6 to be used on a one cubic centimeter robot. The gripper here is shown holding a though hole resistor. The electrostatic inchworm motor on the gripper can travel up to 1 millimeter, produce more than 1 gram of force while consuming less than 1 milliwatt of power, and consume almost no power when holding.
Carbon Fiber Pushers
An electrostatic inchworm motor capable of linearly moving a 7 micrometer diameter carbon fiber with micrometer precision7. This device could be used to build a neural implant system for a brain-machine interface, as well as a microrobotic fiber crawling spider.
Miniature Rockets with MEMS Control Surfaces
Miniature rockets can be maneuvered aerodynamically with MEMS motors and control surfaces8, and may provide a solution for micro-air vehicle (MAV) swarm interception.
The first picture shows an assembled miniature rocket and the second picture shows a close-up view of the MEMS motor and control surface.
Electrostatic Inchworm Motors
High force (>1gf), large travel (>1mm), and low power (<1mW) linear micromotors can be made using a single mask in a silicon-on-insulator MEMS process6,9.
The first video shows a motor designed to displace 1 millimeter finally breaking after it is commanded to displace more than 2 millimeters. The motor contains more than 3,000 moving capacitor plates. The video is in real time. For scale, the entire width of the video is approximately 6 millimeters.
The second video shows a microrobot using a motor to store mechanical energy in a spring etched into substrate silicon. The motor's output shaft is attached to a 10:1 mechanical advantage gain mechanism. The motor contains more than 3,000 moving capacitor plates. The video is 4x faster than real time.
The Micro Inertial Measurement System (MIMSY)
MIMSY is a 1.6cm X 1.6cm open-source wireless sensor node with a 32-bit ARM Cortex-M3 microprocessor, 802.15.4 transceiver, and 9-axis IMU10. MIMSY has been used to create a smart mattress, to study the reliability and latency of various network topologies, for industrial automation control11, and as part of the avionics for miniature rockets8 and Crazyflie quadcopters12.