ceramic based
Fabrication of piezoelectric thick-film bimorph micro-actuators from bulk ceramics using batch-scale methods
R.P.Jourdain and S.A.Wilson
Materials Department, School of Applied Sciences, Cranfield University, Cranfield, Bedfordshire, MK43 0AL, United Kingdom
Abstract
Piezoelectric ceramic films in the 20-60 micron thickness range are rarely employed today in commercial micro-mechanical devices, even though their expected force capability suggests that they are well suited to many micro-fluidic and micro-pneumatic applications. Some examples would be micro-scale fuel cells and micro-combustors. Head sliders, radio-frequency (RF) micro-switches and powered micro-optics are further potential application areas. These are only a few and the barriers in bringing them into reality are those of processing compatibility rather than commercial desirability. Such issues are being addressed in the EU Framework 6 Project ‘Q2M’, which focuses on batch-scale fabrication issues for high quality new micromechanical devices that are cost-effective and which have extended capabilities.
This paper discusses a potential batch-scale production route for piezoelectric thick-film bimorph microactuators that combines ultra-precision grinding of ceramics and femto-second laser machining, along with standard micro-fabrication techniques such as wafer bonding. This new method has the key advantage that many different shapes and thicknesses of actuator can be made with only minor process changes, meaning that actuators can be designed to suit their intended application. It contrasts with current practice whereby micro-actuators are often designed around a limited range of standard components, with consequent reduction in their achievable performance. The examples used are a 6mm diameter plane-spiral bimorph actuator for integration into a polymeric micro-valve and 2-5mm long bimorph cantilevers intended for use in
a new type of silicon ‘house’ micro-valve, with pneumatic applications.
categories
actuators | Bimorph | ceramic based | femto-second | Mechanical machining | MEMS | micro-actuator | PZT | ultra-precision grinding | wafer bonding
| 189 reads | Structure-Property Relationship of Dispersants used in Ceramic Feedstock Development
T. Hanemann(a)(b), R. Heldele(a)(b), J. Haußelt(a)(b)
a: Forschungszentrum Karlsruhe, Institut f. Materialforschung III, 76021 Karlsruhe, Germany
b: Albert-Ludwigs-Universität Freiburg, Institut f. Mikrosystemtechnik (IMTEK), 79110 Freiburg, Germany
Abstract
With respect to polymer-filler composite (feedstock) development for the different variants of powder injection molding the use of dispersants or surfactants is essential for a large filler load and a homogenous feedstock quality. In this paper the influence of a series of citrate derived dispersants on the viscosity of feedstock systems with different binder composition and ceramic fillers will be described. Citrates posses four polar functionalities, which can interact with the hydroxy-groups at the alumina or zirconia surface. The investigated surfactants differ in the extension of the lipophilic end chains (ethyl or butyl) and in the presence of one free hydroxy group, which is masked partially by an acetic acid group. The impact of the dispersant concentration, molecular structure, dipole moment and the used binder composition will be discussed in terms of the resulting composite feedstock flow behaviour, some structure-property relationships can be found.
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