Carbon MEMS from the nanoscale to the macroscale: Novel fabrication techniques and applications in electrochemistry

Micro electromechanical systems (MEMS) have strongly impacted our way of life in the last two decades. From accelerometers and gyroscopes that ensure your driving safety, to inkjet printer cartridges that transpose your ideas onto paper, to micromirrors that enable your small projectors. MEMS have become more and more ubiquitous.; Silicon, the material on which the semiconductor industry based its revolution, has so far been the material of choice for MEMS. While silicon is a great platform for constructing electronics, it is less than ideal for applications that involve electrodes exposed to aggressive liquid and gaseous environments. Carbon is one of the most commonly used materials when it comes to electrochemical applications, it is therefore the best candidate to carry over the trend of miniaturization in arenas such as smart chemical sensing, biological microdevices, miniature power, etc.; Recent advances in engineering nanoscale structures show great promise towards delivering higher performance sensors, detectors, transistors, displays, etc. In order to leverage the power of nanostructures in general, new manufacturing processes that can bridge between the nanoscale and the macroscale are needed. Such integrated fabrication methods are essential in enabling the transfer of the advantages boasted by nanostructures from the research labs towards mass manufacturing.; The present work starts by introducing the basic photolithography technique that has been used so far to fabricate Carbon MEMS (C-MEMS). Several novel techniques stemming for the original process are then described in details and lithium-ion microbattery anodes are presented as an example application of these novel fabrication methods. These Carbon MEMS anodes are characterized through a combination of cyclic voltammetry and electrochemical impedance spectroscopy (OS). A new finite element analysis (FEA) technique is then proposed to more accurately model the current density distributions of 3Dimensional C-MEMS batteries without the need for very complex multiphysics modeling. The results show that variations in current density distributions, previously reported in the literature, were exaggerated.; The work then moves to describe two other novel multiscale C-MEMS fabrication techniques that attempt to bridge the gap between macro and nano scales. The first involves the combination of electrochemistry and photolithography in order to achieve fractal like structures made entirely of carbon. The second uses a solution based deposition technique that yields fine submicron glassy carbon wires suspended between microposts hundreds of microns apart. Although previously reported in the literature, the exact fabrication mechanism of these suspended nanowires was originally attributed to the wrong mechanism. The two phase flow deposition mechanism (i.e. stretching flow) is demonstrated and the original interpretation mechanism is rebutted.; It is then shown how Carbon MEMS structures can be used in a multitude of applications, e.g. dielectrophoresis, selective trapping, particle separation and manipulation.