Novel electrode material synthesis for energy storage applications: is the synthesis of novel electrode materials with microstructures engineered for efficient charge storage for applications including lithium-ion batteries, electrochemical capacitors, biofuel cells, etc. A host of materials both pristine and composites, with different morphologies have been fabricated including transition metal oxides (TMOs), nano-confined SnO2, lithium containing TMOs, nanostructured carbons, etc. using electrostatic spray deposition (ESD), electrospinning, and electrophoretic deposition (EPD).
Microsupercapacitors: The development of miniaturized electronic systems such as smart cards, wireless sensors and sensor networks, RFID tags, miniaturized MEMS and implantable devices, etc. has stimulated the demand for miniaturized power sources. Typically, the power consumption for most implantable devices ranges from µW-mW. In order to address the energy and power demands for microsystems, Dr. Wang has actively worked toward fabricating micro-electrochemical energy storage devices – including microsupercapacitors and also micro-hybrid capacitors. The device realization comprises a three-step process: i) synthesis of Au or C microelectrodes; typically the carbon microelectrodes are synthesized using carbon microelectromechanical systems (C-MEMS), which involves the pyrolysis of patterned photoresists; ii) material development and integration onto the microelectrode platform; and iii) electrochemical characterization of the final device.
C-MEMS based micro-biofuel cells: Biofuel cells, which convert biochemical energy into electrical energy, are expected to be a potential solution to the drawbacks presented by conventional batteries, but the power density and operational lifetime requirements for implanted devices have not been met by the current biofuel cells. In order to address the aforementioned shortcomings of biofuel cells, Dr. Wang’s group has investigated C-MEMS based electrodes for micro-biofuel cell applications both theoretically and experimentally. The work includes i) finite element approach for the optimization of electrode design in both steady state and transient state; ii) construction of carbon microelectrodes via C-MEMS; iii) functionalizing different functional groups such as –COOH and –NH2 on the surface of the carbon microelectrodes; iv) immobilizing enzymes on the carbon micro-pillar electrode arrays, and v) characterizing the final device.
C-MEMS based bio-sensing: Dr. Wang’s group has also focused on investigating different strategies to develop functionalized high surface area bio-carbon interface for electrochemical and biosensing applications. The research efforts were mainly dedicated toward 3D carbon microelectrode array synthesis, conformal coating of nanostructured carbons onto the microelectrode, comparing different surface functionalization methods including direct amination, oxygen plasma treatment, diazonium grafting, vacuum UV-treatment, UV/ozone treatment, electrochemical activation, quantification of functionalization, verification of biomolecule attachment, and testing different types of biosensors, i.e., DNA sensor, H2O2 sensor, and protein sensor, based on C-MEMS/NEMS electrode arrays.