The Nanostructured Origami™ process consists of patterning a two-dimensional (2-D) membrane with desired micro- and nanoscale features and then folding it into a three-dimensional (3-D) configuration. Electrochemical capacitors, or supercapacitors, are ideal for origami fabrication because their performance can be enhanced through the use of 3-D geometry and nanostructured materials. A supercapacitor with an electrode area of 350×350μm was created using the origami process and characterized using electrochemical analysis methods. The experimentally measured capacitance values of approximately 1μF are consistent with theoretical predictions.

Nanowires of various materials and configurations have been shown to be highly effective in the detection of chemical and biological species. In this paper, we report a novel, nanosphere-enabled approach to fabricating highly sensitive gas sensors based on ordered arrays of vertically aligned silicon nanowires topped with a periodically porous top electrode. The vertical array configuration helps to greatly increase the sensitivity of the sensor while the pores in the top electrode layer significantly improve sensing response times by allowing analyte gases to pass through freely. Herein, we show highly sensitive detection to both nitrogen dioxide (NO(2)) and ammonia (NH(3)) in humidified air. NO(2) detection down to 10 parts per billion (ppb) is demonstrated and an order-of-magnitude improvement in sensor response time is shown in the detection of NH(3).

The application of silicon microfabrication technologies to electrochemical devices allows reduction of overall device package to potentially increase volumetric power densities. This review first focuses on some exciting developments in microfuel cells, in particular, solid oxide fuel cells (SOFCs) and proton exchange membrane fuel cells (PEMFCs). The emphasis is given to innovative 2D processing methods, novel 2D architectures of microfuel cells, and demonstrated performance in terms of area power densities. Emerging 3D fabrication techniques that are potentially promising to produce 3D electrochemical devices such as 3D cell and stack architectures on the micrometer scale will then be discussed. Lastly this paper highlights some new opportunities in electrode kinetics studies enabled by microfabricated devices}investigation of scaling relationship between microelectrodes and electrochemical responses, which has led to improved fundamental understanding of electrode reactions and rate-limiting steps.

A schematic of the sample chamber and vapor delivery system built in-house. A zero air generator, humidifier, and three mass flow controllers (MFCs) are used to generate the carrier gas and various analyte gas mixtures. The white arrows inside the sample chamber indicate the gas flow impacting onto the sensor. The sample chamber can also be heated for temperature studies.

Multiwalled carbon nanotubes (CNTs) with nickel and cobalt catalyst tips have been grown on foldable titanium nitride membranes. Once magnetized to saturation under an external magnetic field, these ferromagnetic tips, which reside atop each CNT, can be used to actuate the entire membrane on which the nanotubes are grown. Magnetic modeling is performed to analyze the magnetic properties of the teardrop-shaped CNT tips, and initial experimental results show that magnetic torques and forces arising from the CNT tips are sufficient to rotate the membrane up to 180° and keep it latched without springing back.