John Garvey
University: University of Maryland, College Park
Major: Electrical Engineering
Graduation Date: May 2012
Hometown: Boyds, MD
Project: In the Microscopic Robotics Project, I designed and implemented a modification to the control procedures that direct movement of currently operable microscopic robots in NIST’s Microelectromechanical Systems (MEMS) Laboratory. In addition, I introduced a modification to the microfluidic deposition system used to mark these micro-robots with a fluorescent solution, which increases their detectability during interferometric dynamic observation. The micro-robots currently being fabricated at NIST have dimensions measuring in the micrometer (10-6 meter) scale, and consist of two polysilicon components – an untethered scratch drive actuator (USDA) and a curved, cantilevered steering arm. Rather than receiving power directly, these components respond to dynamic control signals by interacting with their operation substrate through a capacitive coupling, in which the micro-robot actuator and arm, along with the insulating dielectric and silicon substrate on which they are placed, form a capacitor-like electromechanical structure. The grid of metal electrodes on the top layer of the substrate directly receives the control signals from a signal generator as two distinct, amplified voltage waveforms.
These signals direct the micro-robots to move forward through the flexing and relaxing of the USDA, or turn in one direction by first lowering the steering arm and then flexing and relaxing the USDA. Using an application programming interface (API) found at the National Instruments (NI) website [2], I designed and wrote source code programmed with NI’s LabVIEW software which interacts with a Nintendo Wiimote and with a multifunction signal generator through Bluetooth and USB connections, respectively, to enable an external, remote-controlled method of teleoperation of the micro-robots. This method of operation, in which the Wiimote buttons are used to control the forward and turning motions of the micro-robots with a single computer program, eliminates the need to use a computer mouse, multiple windows and source code files, and the Run and Stop buttons of each of these files to switch between the transmission of the forward and turning control signals during teleoperation.
The microfluidic deposition system that I created utilizes various plastic unions, nuts, sleeves, ferrules, and adaptors, along with a syringe pump and glass micropipette, to produce a very controlled, filtrated method of transferring the fluorescent solution used to track the micro-robots during operation. This design is an improvement over the previous system because it not only provides more control of the volume of solution deposited − through the use of a filtration system − but also allows for reuse, since a broken micropipette can be replaced simply by loosening a nut and inserting a new pipette. With the previous system, an entirely new apparatus had to be fabricated each time the micropipette at the end of the system broke.
Possible future plans in the Microscopic Robotics Project to increase robot capability include adding a second steering arm to allow bidirectional turns and enabling the independent control of two robots operating simultaneously on the same surface. Applications for this specific type of electrostatically-controlled micro-robots are in the field of micromachining: to construct precise micrometer- or nanometer-scale devices by manipulating individual molecules or atoms in exacting routines.
About me: I grew up in Boyds, MD, just 15 minutes from NIST. I first became interested in electrical engineering, specifically robotics, when a high school physics course inspired me to begin studying electric circuits. This interest led to my experimentation with fabricating robots from scratch at my house. As I designed, constructed, and programmed these robots, I was exposed to various new software programs and circuit theory techniques that prompted me to read more books about robotics. The more I learned, the easier it was to develop ideas for building new robots, and I now realize the extent to which this chain reaction of knowledge and application drives the endless possibilities in the field of robotics in the world today. In an effort to get a chance to work with robots as a researcher in a laboratory setting, rather than solely as a hobbyist, I applied to work on the Microscopic Robotics Project in the NIST SURF program. I have learned a great deal this summer about the nascent, but growing field of micro-robots, which has huge application potential in fields such as medicine and micromachining. I look forward to working more with robots at the micrometer scale in the future and am excited to see how this field of research continues to develop. After graduation, I hope to pursue a career in military robotics.
References:
[1] Donald, B. R., C. G. Levey, C. D. McGray, I. Paprotny, I. Paprotny, and D. Rus. “An untethered, electrostatic, globally controllable MEMS Micro-Robot.” Journal of Microelectromechanical Systems, 1 Feb. 2006, vol. 15, no. 1.
[2] Shearman, S. “Communities: LabVIEW interface to a Wii Remote (“Wiimote”).” 4 Jun. 2009. National Instruments. 8 Jul. 2009 <http://decibel.ni.com/content/docs/DOC-1353>.
