C-MEMS and C-NEMS

Abstract

Our work in carbon-microelectromechanical systems (C-MEMS) suggests that C-MEMS might provide a very interesting material and microfabrication solution to the battery miniaturization problem, active DNA arrays and a wide variety of chemical and biological sensors. We established that it is possible to use C-MEMS to create very high aspect ratio carbon structures (e.g. posts with an aspect ratio > 10), suspended carbon plates and suspended carbon nano-wires (CNEMS). In C-MEMS, photoresist is patterned by photolithography and subsequently pyrolyzed at high temperatures in an oxygen free environment. By changing the lithography conditions, soft and hard baking time and temperature, additives to the resist , pyrolysis time, temperature and environment, C-MEMS permits a wide variety of interesting new MEMS and NEMS applications that employ structures having a wide variety of shapes, resistivity and mechanical properties. From the manufacturing and materials point of view the advantages of using photoresists as the starting material for carbon electrodes include the fact that photoresists can be patterned by photolithography techniques resulting in much finer features than possible with the more traditional silkscreening of carbon inks, and, since photoresists are very controlled and reproducible materials, more reproducible carbon electrode behavior can be expected. In earlier work, we demonstrated that photoresistderived carbon electrodes show excellent electrochemical kinetics comparable to that of glassy carbon for selected electrochemical reactions in aqueous and nonaqueous electrolytes. Here we will demonstrate that arrays of high aspect ratio carbon posts can be charged discharged with Li and that this enables the fabrication of a smart switchable array of batteries (each individual battery is called a baxel). We will also show that C-MEMS can be used in DNA micro-arrays and in a wide variety of novel electrochemical sensors.