Fabrication and electroosmotic flow measurements in micro- and nanofluidic channels

An easy method for fabricating micro- and nanofluidic channels, entirely made of a thermally grown silicon dioxide is presented. The nanochannels are up to 1-mm long and have widths and heights down to 200nm, whereas the microfluidic channels are 20-μm wide and 4.8-μm high. The nanochannels are created at the interface of two silicon wafers. Their fabrication is based on the expansion of growing silicon dioxide and the corresponding reduction in channel cross-section. The embedded silicon dioxide channels were released and are partially freestanding. The transparent and hydrophilic silicon dioxide channel system could be spontaneously filled with aqueous, fluorescent solution. The electrical resistances of the micro- and nanofluidic channel segments were calculated and the found values were confirmed by current measurements. Electrical field strengths up to 600V/cm were reached within the nanochannels when applying a potential of only 10V. Electroosmotic flow (EOF) measurements through micro- and nanofluidic channel systems resulted in electroosmotic mobilities in the same order of those encountered in regular, fused silica capillarie

A single-mask thermal displacement sensor in MEMS

Position sensing in MEMS is often based on the principle of varying capacitance [1]. Alternative position sensing principles include using integrated optical waveguides [2] or varying thermal conductance [3]. Lantz et al demonstrated a thermal displacement sensor achieving nanometre resolution on a 100mm range. However a multi-mask production process and manual assembly were needed to fabricate this displacement sensor. In this work we present a 1-DOF thermal displacement sensor integrated with an actuated stage, and its experimental characterization. The system was fabricated in the device layer of a silicon-on-\ud insulator (SOI) wafer using a single-mask process.\ud \u

Remote Nanoimaging on Mars - Results of the Atomic Force Microscope Onboard NASA's Phoenix Mission

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7-August 11, 201

Developing an Optical Microlever for Stable and Unsupported Force Amplification

— Optical micromachines have the potential to im prove the capabilities of optical tweezers by amplifying forces and allowing for indirect handling and probing of specimens. However, systematic design and testing of micromachine per formance is still an emerging field. In this work we have designed and tested an unsupported microlever, suitable for general-purpose optical tweezer studies, that demonstrates stable trapping performance and repeatable doubling of applied forces. Stable trapping was ensured by analysing images to monitor focus shift when levers oscillated repeatedly, before the best-performing design was selected for force amplification. This study also shows that direct measurement of trap stiffness using the equipartition theorem appears to be a valid method for measuring applied forces on the spherical handles of microlevers

Insects: a protein-rich feed ingredient in pig and poultry diets

The use of insects as a sustainable protein-rich feed ingredient inpig and poultry diets is technically feasible. Insects can turn lowgradebiowaste into proteins.• The amino acid profile of yellow mealworm, common housefly,and black soldier fly is close to the profile of soybean meal withmethionine or methionine + cystine, which are generally the mostlimiting essential amino acids for growing pigs and broilers. Argininecan also become a limiting essential amino acid for broilersfed housefly pupae and mealworm.• Additional research is recommended on digestibility of (processed)insects, inclusion levels in poultry and pig diets, functionalproperties, safety when using biowaste as a rearing substrate,extraction of nutrients, shelf life, and use of left-over substratesand residue products of insects.• To compete with conventional protein sources and become aninteresting link in the animal feed chain to fulfil the globally increasingdemand for protein, cost price of insect production andprocessing should be further reduced

Multiple Andreev Reflection and Giant Excess Noise in Diffusive Superconductor/Normal-Metal/Superconductor Junctions

We have studied superconductor/normal metal/superconductor (SNS) junctions consisting of short Au or Cu wires between Nb or Al banks. The Nb based junctions display inherent electron heating effects induced by the high thermal resistance of the NS boundaries. The Al based junctions show in addition subharmonic gap structures in the differential conductance dI/dV and a pronounced peak in the excess noise at very low voltages V. We suggest that the noise peak is caused by fluctuations of the supercurrent at the onset of Josephson coupling between the superconducting banks. At intermediate temperatures where the supercurrent is suppressed a noise contribution ~1/V remains, which may be interpreted as shot noise originating from large multiple charges.Comment: 7 pages, 7 figures, extended versio