Nanoscale ISFET (ion sensitive field-effect transistor) pH sensors are presented that produce the well-known sub-nernstian pH-response for silicon dioxide (SiO(2)) surfaces and near ideal nernstian sensitivity for alumina (Al(2)O(3)) surfaces. Titration experiments of SiO(2) surfaces resulted in a varying pH sensitivity ∼20 mV/pH for pH near 2 and >45 mV/pH for pH > 5. Measured pH responses from titrations of thin (15 nm) atomic layer deposited (ALD) alumina (Al(2)O(3)) surfaces on the nanoISFETs resulted in near ideal nernstian pH sensitivity of 57.8 ± 1.2 mV/pH (pH range: 2-10; T = 22 °C) and temperature sensitivity of 0.19 mV/pH °C (22 °C ≤ T ≤ 40 °C). A comprehensive analytical model of the nanoISFET sensor, which is based on the combined Gouy-Chapman-Stern and Site-Binding (GCS-SB) model, accompanies the experimental results and an extracted ΔpK ≈ 1.5 from the measured responses further supports the near ideal nernstian pH sensitivity.

We report a new membrane system showing dynamic controllable multiphase transport and separation under steady-state pressure.

We report a new low-cost top-down silicon nanowire fabrication technology requiring only conventional microfabrication processes including microlithography, oxidation, and wet anisotropic plane-dependent etching; high quality silicon nanowire arrays can be easily made in any conventional microfabrication facility without nanolithography or expensive equipment. Silicon nanowires with scalable lateral dimensions ranging from 200 nm down to 10-20 nm and lengths up to approximately 100 microm can be precisely formed with near-perfect monocrystalline cross sections, atomically smooth surfaces, and wafer-scale yields greater than 90% using a novel size reduction method where silicon nanowires can be controllably scaled to any dimension and doping concentration independent of large contacting regions from a continuous layer of crystalline silicon.

A new low-cost, top-down nanowire fabrication technology is presented not requiring nanolithography and suitable for any conventional microtechnology cleanroom facility. This novel wafer-scale process technology uses a combination of angled thin-film deposition and etching of a metal layer in a precisely defined cavity with a single micrometer-scale photolithography step. Electrically functional silicon and metallic nanowires with lengths up to several millimeters, lateral widths of 100 nm, and thicknesses 20 nm have been realized and tested. Device characterization includes a general description of device operation, electrochemical biasing, and sensitivity for sensor applications followed by electrical measurements showing linear i-v characteristics with specific contact resistivity rhoc approximately 4 x 10-4 ohm's cm2 and electrochemical behavior of the oxidized silicon nanowires is described with the site-binding model.

We demonstrate the utilization of selective functionalization of carbon-silicon (C-Si) alkyl and alkenyl monolayers covalently linked to all-(111) surface silicon nanowire (Si-NW) biosensors. Terminal amine groups on the functional monolayer surfaces were used for conjugation of biotin n-hydroxysuccinimide ester. The selective functionalization is demonstrated by contact angle, X-ray photoelectron spectroscopy (XPS), and high-resolution scanning electron microscopy (HRSEM) of 5 nm diameter thiolated Au nanoparticles linked with streptavidin and conjugated to the biotinylated all-(111) surface Si-NWs. Electrical measurements of monolayer passivated Si-NWs show improved device behavior and performance. Furthermore, an analytical model is presented to demonstrate the improvement in detection sensitivity of the alkyl and alkenyl passivated all-(111) Si-NW biosensors compared to conventional nanowire biosensor geometries and silicon dioxide passivation layers as well as interface design and electrical biasing guidelines for depletion-mode sensors.