At IIT Bombay we have successfully developed ?m sized sensors and biosensors based on conducting polymers. We have also shown that several sensors can be integrated to produce an ?electronic tongue?. Such structures have a great potential in developing low-cost diagnostic kits for health-care. Another area of potential application is in electromechanical devices where conducting polymers have a great advantage due to their unique electrochemical properties. Structures like cantilevers and diaphragms can be built by the ?bottoms up? approach. We have initiated studies with polyaniline and PEDOT cantilevers with a view to developing a sensing application. Besides, we believe such studies will provide a window to the fundamental molecular mechanisms involved in the transduction process and a direct measure of the inter-molecular forces. The expansion/contraction of the polymer film is the result of processes of ion insertion/ejection, solvation/desolvation, and coiling/uncoiling of polymer chains. Forces generated/exerted by these interactions are rarely accessible in such a direct manner as they are here. With nanometer size structures the ?signal/noise ratio? of such effects will become more favorable and one can hope to see differences with change in ionic radii, polarity of solvent, and polymer structure. This could lead to a way to estimate the magnitude of forces involved in weak interactions.
       Another class of materials that is being studied at our institute in this context is ceramics. Ceramic actuators and gas sensors are being developed and a nano-structured composite material will have advantages in terms of sensitivity and ease of fabrication.
       It is proposed to study nanometer sized structures of conducting polymers with particular reference to their potential applications. These structures will be fabricated by a variety of techniques including electrochemical, chemical, electrospinning and Langmuir-Blodgett. These structures/devices will be examined/characterized by microscopic techniques including, scanning electron and transmission electron microscopy and atomic force/scanning tunneling microscopy. Besides these, electrochemical, spectroscopic and electrical techniques will be used to characterize devices. EQCM and cantilever studies will also be undertaken to elucidate the actuation process.
       Nanoelectronics: There is a great scope for plastic eletronics because of flexibility, ease of processability and ease of fine tuning of the structures. However, this area is still in infancy because of the limited availability of semiconducting polymers. Polyaniline is easily available but is not stable to air or high temperatures and hence could not be used for commercial applications though it has been shown to exhibit transistor behavior. In case of PEDOT, though it is stable to air and elevated termperature, it can be used because it is not available in semiconducting form essential for nanoelectronics. The Baytron P is the only processable PEDOT materials, but it is in conducting form and can not be isolated in semiconducting form. Therefore, in order to get the reduced semiconducting PEDOT, one has to rely on true soluble PEDOT derivatives. Therefore, our materials are the right materials for these applications.
       Electronic Tongue: Lab on a Chip: Biomedical Sensors: We have demonstrated and published our results sometime back that PEDOT can be used for immunosensing and also for DNA sensing. These biomedical applications have huge commercial potential. However, we could not take this concept to next level because the sensors were made from electropolymerization route. This means one can make one sensor at a time and hence not viable for bulk production. However, we have now developed the soluble PEDOT materials, this means that we can now use the direct printing method for the fabrication of DNA and immuno and other biomedical sensors as printing is suitable for scale up.