Microfluidics Propulsion & System Integration in MEMS Devices

 An undergraduate led research group comprised of students from multiple disciplines of engineering  Mentored by faculty members including Professors Mustafa Yavuz and Omar Ramahi Research interests in:  Integration of microfluidics, RF, photovoltaics, and digital logic for creating advanced devices  Improving MEMS technologies for industry adoption

 Designing a 300 micron diameter device to compete at the 2009 Nanogram Robocup Competition  Robocup is an annual competition held to promote AI, robotics and related fields since 1993  Nanogram is a NIST supported initiative to advance integrated MEMS devices

 Cylindrical design utilizing a photovoltaic cell and two 10 micron air compressors  Pump actuation controlled by two phototransistors  Power delivery through photovoltaic cell  Two phototransistors control pump actuation

 Flexible conductive membrane placed above fixed electrode forms compression chamber  Attraction between membrane and electrode with potential difference leads to air compression

 Shaped nozzles direct air flow to create net force in one direction  Variation between two pumps allow for steering  Computationally derived oscillation of 1mhz creates optimum thrust without resonant effects

 Germanium based IR detector on aluminum substrate  100 micron diameter  Detects wavelengths from 850nm to 1550nm  0 to 10V bias  1 uA dark current

 Substrate is cleaned and Positive Photoresist is spincoated  PMMA (Microchem)  Achieve thickness of 2 microns  Substrate with photoresist is baked

 Mask patterns the electrode layer  Mask is removed and substrate is developed  Electrode layer is sputtered onto the substrate  Chromium (for adhesion) is used and sputtered to ~1 micron thickness  Remaining resists are removed

 PMMA and Copolymer is spincoated above the substrate  Used to pattern walls  Achieve thickness of 4 microns  Shape of pump and channels patterned with “v”-shape

 Patterned membrane shape and developed  Aluminum deposited onto Pattern  Approximately 2-3 microns thick  Remaining resist is removed

 Above membrane, photoresist is spincoated above again  Use of both PMMA and Copolymer  Bake photoresist and then deposit Aluminum  Remove Resist  Formation of top chamber

 Utilization of two different wavelengths for microcompressor control  Control each microcompressor individually

 Complete solar array design for integration onto robot  Theoretical design will be outsourced to a photovoltaic foundry for fabrication  Development of a thin-film RF antenna has begun to use inductive coupling as a method of power transfer  Biocompatibility materials studies  Surface interaction optimization for robotic device movement