MEMS Update: What's Near What's HereAugust 1, 2006 By: Joseph M. Giachino Sensors
The biennial conferences at Hilton Head offer researchers and development engineers an opportunity to present their work in progress and to explore the commercial implications of the results.
The Solid State Sensors, Actuators, and Microsystems Workshop, or as it is more commonly known, the Hilton Head meeting, was held June 4–8, 2006, in Hilton Head, SC. This is one of the premier venues for researchers and development engineers to exchange information on the latest advances in microsystems. This thirteenth biennial assembly featured a number of commercial products that use MEMS (microelectromechanical) technology and some MEMS devices very near the commercial product stage.
This month s cover photo is courtesy of the Engineering Research Center for Wireless Integrated Microsystems (WIMS, www.wimserc.org, an NSF Engineering Research Center). The background image shows wafer-level integration of vacuum-sealed capacitive pressure sensors. On the fingertip are front and back views of a fully integrated microsystem for autonomous data gathering.
MEMS devices began serious commercialization in the late 1970s in response to the demand for automotive pressure sensors and have continued to expand in both automotive and non-automotive applications. Here is a short review of some of the devices already commercialized and some sensors that are nearing commercialization.
The Knowles SiSonic (www.knowlesacoustics.com) microphone is targeted at the low-cost, high-volume consumer electronics market. SiSonic is a condenser microphone comprising a MEMS die and a CMOS die in an acoustic housing (Figure 1). The one distinct advantage this microphone has over the electret condenser microphone (ECM) is that it can withstand the lead-free solder reflow cycles. The ECM must be inserted after the reflow cycles because it cannot withstand the reflow temperatures. This ability to be reflowed with other components permits the MEMS microphone to be pick-and-placed like any other component and thus leads to a lower cost for the integrator.
Figure 1. SiSonic condenser microphone package with lid removed; this is a first-generation version; subsequent generations have been developed
Near-Infrared Analysis Tool
The Polychromix Phazir (www.polychromix.com) is a handheld NIR analysis tool and is made possible by an innovative MEMS optical modulator. The near-infrared portion of the spectrum is particularly useful for solids and liquids analysis in the pharmaceutical and agricultural products industries. The unit can be used to collect application-specific spectra in the field. MEMS technology has taken a laboratory-quality device and made it portable.
The conventional way to perform chemical identification in many materials is to repeatedly measure the spectrum of a sample and then analyze that spectrum to identify characteristic absorption lines of target chemicals. This method can be expensive and time-consuming, and requires highly skilled technicians. The MEMS modulator makes analyses portable, flexible, and cost-effective. Moreover, many of the tasks can be performed by nontechnical staff with minimal training—and achieve the same high-quality results.
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