Eric J Wilhelm's |
I am developing an additive
microfabrication technique based on liquid embossing nanoparticle
colloids. The potential applications include truly 3-dimensional MEMS
and logic, biological scaffolding, and photonic band gaps.
Publications and awards:
Fuller, S. B., E. J. Wilhelm, et al. (2002). "Ink-jet printed
nanoparticle microelectromechanical systems." Journal of
Microelectromechanical Systems 11(1): 54-60.
We report a method to
additively build three-dimensional (3-D) microelectromechanical
systems (MEMS) and electrical circuitry by ink-jet printing
nanoparticle metal colloids. Fabricating metallic structures from
nanoparticles avoids the extreme processing conditions required for
standard lithographic fabrication and molten-metal-droplet
deposition. Nanoparticles typically measure I to 100 nm in diameter
and can be sintered at plastic-compatible temperatures as low as 300
degreesC to form material nearly indistinguishable from the bulk
material. Multiple ink-jet print heads mounted to a
computer-controlled 3-axis gantry deposit the 10% by weight metal
colloid ink layer-by-layer onto a heated substrate to make
two-dimensional (2-D) and 3-D structures. We report a high-Q resonant
inductive coil, linear and rotary electrostatic-drive motors, and
in-plane and vertical electrothermal actuators. The devices, printed
in minutes with a 100 mum feature size, were made out of silver and
gold material with high conductivity,and feature as many as 400
layers, insulators, 10 : 1 vertical aspect ratios, and etch-released
mechanical structure. These results suggest a route to a desktop or
large-area MEMS fabrication system characterized by many layers, low
cost, and data-driven fabrication for rapid turn-around time, and
represent the first use of ink-jet printing to build active MEMS.
Bulthaup, C. A., E. J. Wilhelm, et al. (2001). "All-additive
fabrication of inorganic logic elements by liquid embossing." Applied
Physics Letters 79(10): 1525-1527.
We report an all-additive
patterning technique, liquid embossing, in which a thin liquid film is
embossed by an elastomeric stamp. We show that, for sufficiently thin
films, isolated features are produced as the stamp contacts the
underlying substrate, and that the liquid remains patterned even after
removal of the stamp. Such an approach enables the rapid patterning of
inorganic nanocrystal solutions, as capping groups and solvents can
volatilize efficiently at the exposed liquid surface. Using this
technique, we have fabricated all-printed all-inorganic transistors,
photodetectors, and resistors, as well as multilayer structures with
sacrificial layers and vias. Such an approach may enable a route to
all-printed inorganic semiconductor logic and machines.
Mihm, S. (2000). "Print your next PC." Technology Review 103(6): 66-70.
Winner of the 2000 Collegiate Inventors Competition (with Colin Bulthaup)
C. Bulthaup, E.J. Wilhelm, B.N. Hubert, B.A. Ridley, and
J.M. Jacobson, "Direct Fabrication of All-Inorganic Logic Elements and
Microelectromechanical Systems from Nanoparticle Precursors", Material
Research Society symposium on Non-lithographic and lithographic
methods for nanofabrication, 2000.
Perez, J. M., E. J. Wilhelm, et al. (2000). "The use of power
ultrasound coupled with magnetic separation for the solid phase
synthesis of compound libraries." Bioorganic & Medicinal Chemistry
Letters 10(2): 171-174.
Enhanced reaction rates are observed when
power ultrasound is utilized as a substitute for mixing during solid
phase organic chemical reactions on a paramagnetic support. Power
ultrasound is also used to facilitate the washing of the paramagnetic
support as it is magnetically separated from the reaction
mixture. Selective examples from a library targeting the kappa-opioid
receptor are presented.
Iagnemma, K., R. Burn, et al. (2000). "Experimental validation of
physics-based planning and control algorithms for planetary robotic
rovers." Experimental Robotics Vi 250: 319-328.
exploration is a major component of the United States' NASA space
science program. The focus of our research is to develop rover
planning and control algorithms for high-performance robotic planetary
explorers based on the physics of these systems. Experimental
evaluation is essential to ensure that unmodeled effects do not
degrade algorithm performance.. To perform this evaluation a low-cost
rover test-bed has been developed. It consists of a rocker-bogie type
rover with an on-board manipulator operating in a rough-terrain
environment. In this paper the design and fabrication of an
experimental rover system is described, and the experimental
validation of several rover control algorithms is presented. The
experimental results obtained are key to the evaluation and validation
of our research.
B.A. Ridley, B. Nivi, B.N. Hubert, C. Bulthaup, E.J. Wilhelm, and
J.M. Jacobson ,"Solution Processed Inorganic Transistors and
Sub-Micron Non-Lithographic Patterning Using Nanoparticle Inks",
Nanophase and Nanocomposite Materials III, Mater. Res. Soc. Proc. 581,
pp 115-120, 1999.