When using appropriate materials and microfabrication techniques, with the small dimensions the mechanical stability of microstructured devices allows for processes at high pressures without loss in safety. The largest area of applications has been demonstrated in green chemistry and bioprocesses, where extraction, synthesis and analyses often excel at high densities and high temperatures. This is accessible through high pressures. Capillary chemistry has been used since long but, just like in low-pressure applications, there are several potential advantages in using microfluidic platforms, e.g., planar isothermal set-ups, large local variations in geometries, dense form factors, small dead volumes and precisely positioned microstructures for control of reactions, catalysis, mixing and separation. Other potential applications are in, e.g., microhydraulics, exploration, gas driven vehicles, and high-pressure science. From a review of the state-of-art and frontiers of high pressure microfluidics, the focus will be on different solutions demonstrated for microfluidic handling at high pressures and challenges that remain.
Microoptoelectromechanical (MOEMS) systems with InP based micromechanics are proposed for devices with wide tuning ranges in the optical wavelengths where InP optoelectronics are normally used. To evaluate if these InP based micromechanical structures may be strong enough the mechanical strengths of surface micromachined epitaxial InP micro beams are evaluated. Reactive ion etching (RIE) with CH4:H2:H2Ar is used to structure the beams. A sacrificial InGaAs layer is below the InP microstructures and selectively etched by HCl:H2O2:H2O in ratios 1:1:10 to release the InP beams. Sublimation of tert-butanol is used to dry the micro structures. The RIE conditions are shown to be of large importance, since the induced surface defects are here the dominant reasons for fracture. Bending strength values up to 3.1 GPa were measured, i.e. much higher than for the strongest construction steel. Weibull statistics show that it is possible to make micromachines for typical MOEMS applications with acceptable loss in yield due to fracture probability, i.e. with a fracture probability of 0.0001 for 100 MPa maximum bending stress.
An empirical relationship between the long wavelength edge of the residual ray band in the IRreflectance
of partly ionic compounds and bulk hardness is demonstrated. The group of materials studied
includes alkali halides, semi-conductors and some hard compounds, mostly with cubic structure and a few
with hexagonal. The correlation is shown for the Young modulus, the melting temperature and also to
some extent the indentation hardness. The Young moduli cover a range from 10 to almost 500 GPa and the
melting temperatures vary from 600 to 3000°C.
Conference Committee Involvement (7)
Smart Sensors, Actuators and MEMS
4 May 2009 | Dresden, Germany
Smart Sensors, Actuators and MEMS
2 May 2007 | Maspalomas, Gran Canaria, Spain
Photonic Crystal Materials and Devices
3 April 2006 | Strasbourg, France
Smart Sensors, Actuators, and MEMS II
9 May 2005 | Sevilla, Spain
Photonic Crystal Materials and Nanostructures
27 April 2004 | Strasbourg, France
Device and Process Technologies for Microelectronics, MEMS, and Photonics
10 December 2003 | Perth, Australia
Smart Sensors, Actuators, and MEMS
19 May 2003 | Maspalomas, Gran Canaria, Canary Islands, Spain
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