Self-aligned nano-gaps and nano-channels via conventional photolithography and pattern-size reduction technique

A simple method for the fabrication of self-aligned nanogaps and fluidic nanochannels by using conventional photolithography combined with patterned-size reduction technique is presented. The method is based on the complete conversion of a photolithographically microstructured metal layer - exhibiting a high expansion coefficient - to a metal oxide with an improved pattern size resolution using thermal oxidation. With this technique, there are no principal limitations to fabricate nanostructures with different layouts down to several nanometer dimensions. In this work, the proposed method is experimentally demonstrated by preparing self-aligned nanogaps and nanochannels on a Si-SiO2 substrate down to 15-20 nm dimensions. (C) 2009 Elsevier Ltd. All rights reserved

Field-programmable gate array based controller for multi spot light-addressable potentiometric sensors with integrated signal correction mode

A light-addressable potentiometric sensor (LAPS) can measure the concentration of one or several analytes at the sensor surface simultaneously in a spatially resolved manner. A modulated light pointer stimulates the semiconductor structure at the area of interest and a responding photocurrent can be read out. By simultaneous stimulation of several areas with light pointers of different modulation frequencies, the read out can be performed at the same time. With the new proposed controller electronic based on a field-programmable gate array (FPGA), it is possible to control the modulation frequencies, phase shifts, and light brightness of multiple light pointers independently and simultaneously. Thus, it is possible to investigate the frequency response of the sensor, and to examine the analyte concentration by the determination of the surface potential with the help of current/voltage curves and phase/voltage curves. Additionally, the ability to individually change the light intensities of each light pointer is used to perform signal correction. (C) 2011 Elsevier Ltd. All rights reserved