(Outstanding Achievement Award of the Sensor Division) From Antibody to X-ray 25 Years in MEMS Sensors

Micromachining silicon with anisotropic etching solutions has been a core technology in MEMS for over twenty years and resulted in some novel structures including high emissivity surfaces to increase heat transfer and X-ray focusing devices built for Argonne National Laboratories.  A key challenge in biosensing is achieving selectivity which is often provided by immobilizing antibodies at an electrode surface or on a magnetic bead for preconcentration of a target. Impedance based sensing for low power, and direct detection of microbial toxins was studied at porous platinum electrodes, at the University of Illinois at Chicago and Illinois Institute of Technology. This method can be compared with energy generation by enzymes using thermopiles, such as glucose sensors, and redox recycling at interdigitated electrode arrays for the detection of cytokines in a sandwich assay. We are currently investigating methods to improve sampling and pre-concentration through efficient bead-based manipulation using rotating magnetic fields. The use of a CD platform with centrifugal micro-fluidic pumping system will also provide a high throughput approach for target capture using magnetic beads. Manipulation of fluid transport using magnetic bi-directional latching microvalves was investigated for direct methanol fuel cells and miniature gas chromatography systems. The control of sample injection is a critical component of GC systems. Miniature GC columns with integrated heaters have now been developed to improved separation efficiency. These systems show great promise for low power portable chemical analysis systems. Low power sensors are needed, which can include cantilever sensors possessing exquisite sensitivity for chemical detection. We have investigated metal organic framework films, a nanoporous coating, in collaboration with Sandia National Laboratories, on cantilever sensor for detection of VOC’s. This mechanical based detection approach shows improved reproducibility and stability while using minimal power. MEMS accelerometers and gyroscopes are now in most cell phones, while ultra-low power chemical sensors are yet to be integrated. However sensors based upon changes in the thermophysical properties of gases, under development in collaboration with KWJ Engineering, may soon provide gas detection to monitor the environment, improve safety, and even provide breath analysis for heath care.