Yanou Yang

Virus detection using nanoelectromechanical devices

We have used a resonating mechanical cantilever to detect immunospecific binding of viruses, captured from liquid. As a model virus, we used a nonpathogenic insect baculovirus to test the ability to specifically bind and detect small numbers of virus particles. Arrays of surface micromachined, antibody-coated polycrystalline silicon nanomechanical cantilever beams were used to detect binding from various concentrations of baculoviruses in a buffer solution. Because of their small mass, the 0.5μm×6μm cantilevers have mass sensitivities on the order of 10−19g∕Hz, enabling the detection of an immobilized AcV1 antibody monolayer corresponding to a mass of about 3×10−15g. With these devices, we can detect the mass of single-virus particles bound to the cantilever. Resonant frequency shift resulting from the adsorbed mass of the virus particles distinguished solutions of virus concentrations varying between 105 and 107pfu∕ml. Control experiments using buffer solutions without baculovirus showed small amounts (<...

A scanning tip electrospinning source for deposition of oriented nanofibres

We present a method for controlled deposition of oriented polymeric nanofibres. The method uses a microfabricated scanned tip as an electrospinning source. The tip is dipped in a polymer solution to gather a droplet as a source material. A voltage applied to the tip causes the formation of a Taylor cone, and at sufficiently high voltages, a polymer jet is extracted from the droplet. By moving the source relative to a surface, acting as a counter-electrode, oriented nanofibres can be deposited and integrated with microfabricated surface structures. For example, we deposited fibres of polyethylene oxide with diameters ranging from 100 to 1800 nm, with the diameter primarily depending on the concentration of the polymeric solution. In addition to the uniform fibre deposition, the scanning tip electrospinning source can produce self-assembled composite fibres of micro-and nanoparticles aligned in a polymeric fibre. We also deposited oriented conductive polymeric fibres of polyaniline and investigated the conductivity of these fibres as components for polymeric nanoelectronics.

Microfluidic encapsulated nanoelectromechanical resonators

Resonant nanoelectromechanical systems have been demonstrated as sensitive mass detectors with subattogram and even single molecule sensitivity [Ilic et al., Nano Lett. 5, 925 (2005); Ilic et al., J. Appl. Phys. 95, 3694 (2004)]. Measurements of sub-ng/ml protein concentrations and DNA hybridization using deflection based microelectromechanical system (MEMS) devices have also been shown [Wu et al., Nat. Biotechnol. 19, 856 (2001); Fritz et al., Science 288, 316 (2000)]. Sample delivery is generally difficult in such cases requiring the entire device chip to be submersed into an analyte containing mixture. Additionally, in the case of MEMS resonators, high vacuum is required to remove viscous damping to improve sensitivity. In this work, the authors present a method where arrays of nanoelectromechanical devices are encapsulated in individually accessible, parallel microfluidic channels. The microchannels were used for delivery of liquids and nitrogen (for drying). The channels were pumped down to pressures...

Chapter 6:Microfabricated Parylene Electrospray Tips Integrated with Cyclo-Olefin Microchips for ESI-MS

Microchip electrospray ionization mass spectrometry has become an active research area in recent years, driven by the need for high-throughput analysis in areas such as proteomics, drug screening, pharmaceutical research and environmental analysis. For many modern mass spectrometric-based analyses, ...