| Sensing of chemical and biological analytes has assumed great importance, especially for defense, homeland security and point-of-care medical diagnostics. There is a need for developing sensing systems that can be portable, cost-effective and do not necessitate trained personnel for their operation. Microsensors for chemical and biological species have the capability to selectively recognize liquid and gaseous analytes and convert the sensing event into a form that can be easily transmitted over a communication network, such as an electrical or optical signal. These devices integrate on-chip sensing, detection and sample acquisition/handling modules to provide a portable solution. Realizing chemical and biological sensors using microfluidic lab-on-a-chip techniques can lead to efficient sensing systems.; In this work, device structures for sensing chemical and biological species, finding application in sensing analytes exhibiting enzymatic activity are designed, fabricated and tested. The sensing schemes revolve around the dissolution/cleavage of a chemically/biologically functionalized membrane, by the analyte. Microfluidic devices to transduce the membrane dissolution event into electrical and optical signals are developed. Microsensors leveraging on orientational transitions of thermotropic nematic liquid crystals to sense vapor phase analytes are realized. Micro-structures enabling gas-liquid interactions in fluidic channels, with application in sensing air-borne analytes are also implemented. The fabrication platform for these systems is based on the merger of microfluidic tectonics and IC-based MEMS technology. The devices offer benefits in portability, cost, ease of fabrication and integration with electronics. |
