.Microelectromechanical Systems (hlEMS) packaging is much different from conventional integrated circuit (IC) packaging. Many MEMS devices must interface to the environment in order to perform their intended fimction, and the package must be able to facilitate access with the environment while protecting the device. The package must also not interfere with or impede the operation of the MEMS device. The die attachment material should be low stress, and low outgassing, while also minimizing stress relaxation overtime which can lead to scale factor shifts in sensor devices. The fabrication processes used in creating the devices must be compatible with each other, and not result in damage to the devices. Many devices are application specific. requiring custom packages that are not commercially available. Devices may also need media compatible packages that can protect the devices from harsh environments in which the MEMS device may operate. Techniques are being developed to handle, process, and package the devices such that high yields of ftmctional packaged parts will result. Currently, many of the processing steps are potentially harmful to MEMS devices and negatively affect yield. It is the objective of this paper to review and discuss packaging challenges that exist for MEMS systems and to expose these issues to new audiences from the integrated circuit packaging community.
This paper reports a new type of energy cell based on micromachined carbon nanotube film (CNF)-lead zirconate titanate cantilevers that is fabricated on silicon substrates. Measurements found that this type of micro-energy cell generates both AC voltages due to the self-reciprocation of the microcantilevers and DC voltages due to the thermoelectric effect upon exposure to light and thermal radiation, resulting from the unique optical and thermal properties of the CNF. Typically the measured power density of the micro-energy cell can be from 4 to 300 μW cm(-2) when it is exposed to sunlight under different operational conditions. It is anticipated that hundreds of integrated micro-energy cells can generate power in the range of milliwatts, paving the way for the construction of self-powered micro- or nanosystems.
In every engineering course there is a concern about how much the students are actually learning. The physics community has addressed this through the development of an assessment instrument called the Force Concept Inventory. More recently this has been expanded to the development of Engineering Concept Inventories. Universities affiliated with the N.S.F. sponsored Foundation Coalition have developed a number of these inventories. A Materials Concept Inventory has been developed by faculty from Arizona State University and Texas A & M University. They have reported on their work at the 2003 and 2004 A.S.E.E. Annual Conferences 1,2. They have encouraged further refinement of the inventory as a way to help measure the effectiveness of introductory materials engineering courses. A Beta version of this inventory has been graciously provided to Louisiana Tech University. This inventory has been used in seven different sections of our introductory materials engineering course taught during the 2003-2004 and 2004-2005 school years. Approximately 210 students have taken the inventory at the beginning and end of the course. The use of this assessment instrument in our course has provided insight into what is being taught effectively and what areas need improvement. There was a reasonably good correlation between student performance on the inventory post test and the student grade in the course.
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