|Abstract or Summary
- Since the dawn of the computer age, there has been a push to create miniature
devices. These devices were initially integrated circuit (IC) devices to perform
calculations for computers. As the technology progressed, the scope of the devices
diverged to included microelectromechanical (MEMS) devices, meaning that the devices
perform mechanical movements via electrical actuation. More recently, a new generation
of devices has evolved called microtechnology-based energy and chemical systems
(MECS). MECS may employ MEMS technology, however the systems are not designed
to produce only mechanical movement. MECS deal with heat and mass transfer, the
basic processes used in energy, chemical and biological systems, in the mesoscale realm.
Mesoscale devices range from the size of a sugar cube to the size of a human fist.
The possibilities of MECS have not been realized. Heating and cooling systems,
chemical mixing/distribution, and locking systems are all potential applications. The
devices require: 1) revolutionary design, accounting for the scaling effects on device
performance; 2) new fabrication technologies for the creation of these designs; and 3)
good material properties for mechanical and chemical interactions.
Fabrication requirements for MECS are different than for MEMS in that MECS
generally require non-silicon metals. Metal microlamination (MML) has been introduced
as a general practice for meeting the fabrication requirements for MECS. Prior MML
fabrication methods have emphasized the use of diffusion bonding, soldering, or brazing
This thesis will introduce: 1) a novel microflapper valve design fabricated in mild
steel using a novel microprojection welding technique; 2) a novel microfloat valve design
fabricated in mild steel using a novel capacitive dissociation process for creating free floating geometries. The devices are characterized by comparing actual flow rates to theoretical flow rates of equivalent orifice sizes.
Preliminary results show that the microfloat valve achieved an average diodicity (free flow versus leakage rate) ratio of 11.19, while the microflapper valve achieved an average diodicity ratio of 4.08. The theoretical orifice sizes of the microfloat and microflapper valves are 0.629 mm and 0.611 mm respectively. These results suggest that the float valve is the superior design.