UW NANOROBOTICS GROUPMicrofluidics Propulsion & System Integration in MEMS Devices

ABOUT UW_NRG

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

PROJECT

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

DESIGN OVERVIEW 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

MICROCOMPRESSOR – PRINCIPLE

Flexible conductive membrane placed above fixed electrode forms compression chamber

Attraction between membrane and electrode with potential difference leads to air compression

MICROCOMPRESSOR – DESIGN

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

POWER TRANSFER

Germanium based IR detector on aluminum substrate

100 micron diameter Detects wavelengths from

850nm to 1550nm 0 to 10V bias 1 uA dark current

PUMP FABRICATION

Substrate is cleaned and Positive Photoresist is spincoated PMMA (Microchem) Achieve thickness of 2 microns

Substrate with photoresist is baked

PUMP FABRICATION

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

PUMP FABRICATION

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

PUMP FABRICATION

Patterned membrane shape and developed

Aluminum deposited onto Pattern Approximately 2-3 microns thick

Remaining resist is removed

PUMP FABRICATION

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

CFD ANALYSIS

CONTROL OF MICROCOMPRESSOR

Utilization of two different wavelengths for microcompressor control

Control each microcompressor individually

NEXT STEPS

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