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

Suspended photonic waveguide arrays for submicrometer alignment

This paper presents a new alignment concept for the alignment of multichannel photonic intergrated circuits (PICs) using flexible photonic waveguides on one of the PICs that are positionable by integrated micro electro mechanical system (MEMS) actuators. The concept aims for high precision and high degree of assembly process automation. The proposed concept includes pre-alignment of both PICs on a common substrate followed by fine-alignment using the on-chip flexible waveguides and MEMS functionality. This paper introduces the alignment approach and reports on the development and fabrication of suspended and mechanically flexible photonic waveguides. Single suspended waveguide beams and suspended arrays with two and four coupled parallel waveguide beams of different lengths (250 ?mto 1000 ?m) and different widths (18 ?mto 34 ?m) are designed and fabricated. After fabrication, waveguide beam fracturing is observed. The fabrication process has been extended by an additional under-etching step in order to reduce beam fracturing. The static out-of-plane deflection of the fabricated devices follows a specific profile with a dominating upward curvature resulting in a measured maximum out-of-plane deflection of 2% of the length. The beam stiffness of the fabricated devices is measured and proves to be within the available force of microactuators.Precision and Microsystems EngineeringMechanical, Maritime and Materials Engineerin

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