Spontaneous mechanical oscillation of a DC driven single crystal

There is a large interest to decrease the size of mechanical oscillators since this can lead to miniaturization of timing and frequency referencing devices, but also because of the potential of small mechanical oscillators as extremely sensitive sensors. Here we show that a single crystal silicon resonator structure spontaneously starts to oscillate when driven by a constant direct current (DC). The mechanical oscillation is sustained by an electrothermomechanical feedback effect in a nanobeam, which operates as a mechanical displacement amplifier. The displacement of the resonator mass is amplified, because it modulates the resistive heating power in the nanobeam via the piezoresistive effect, which results in a temperature variation that causes a thermal expansion feedback-force from the nanobeam on the resonator mass. This self-amplification effect can occur in almost any conducting material, but is particularly effective when the current density and mechanical stress are concentrated in beams of nano-scale dimensions

Role of Glomerular Proteoglycans in IgA Nephropathy

Mesangial matrix expansion is a prominent feature of the most common form of glomerulonephritis, IgA nephropathy (IgAN). To find molecular markers and improve the understanding of the disease, the gene and protein expression of proteoglycans were investigated in biopsies from IgAN patients and correlated to clinical and morphological data. We collected and microdissected renal biopsies from IgAN patients (n = 19) and from healthy kidney donors (n = 14). Patients were followed for an average time of 4 years and blood pressure was according to target guidelines. Distinct patterns of gene expression were seen in glomerular and tubulo-interstitial cells. Three of the proteoglycans investigated were found to be of special interest and upregulated in glomeruli: perlecan, decorin and biglycan. Perlecan gene expression negatively correlated to albumin excretion and progress of the disease. Abundant decorin protein expression was found in sclerotic glomeruli, but not in unaffected glomeruli from IgAN patients or in controls. Transforming growth factor beta (TGF-β), known to interact with perlecan, decorin and biglycan, were upregulated both on gene and protein level in the glomeruli. This study provides further insight into the molecular mechanisms involved in mesangial matrix expansion in IgAN. We conclude that perlecan is a possible prognostic marker for patients with IgAN. In addition, the up-regulation of biglycan and decorin, as well as TGF-β itself, indicate that regulation of TGF-β, and other profibrotic markers plays a role in IgAN pathology

CMOS biosensor using TSV interposer technology

This paper reports on the successful manufacture of metallized TSV interposer technology as a through molded via element in wafer level packaging of CMOS biosensors. The work has been executed by Silex Microsystems and Fraunhofer IZM, within the EU-consortium CAJAL4EU, where originally 29 partners were developing nanoelectronics-based biosensor technology platforms [1]. The finished metallized TSV interposers fabricated by Silex's 8" line were electrically characterized before molding and showed low resistance (mean resistance 10.3mΩ/Via, with Ï of 2.4) and a high yield of 99.6 %. The Chip in Polymer (CiP) reconfigured wafers were fabricated by IZM. The TSV interposers and CMOS biosensor chips die were interconnected using a PCB-based redistribution allowing lowcosi heterogeneous integrated packaging and separation between the active biosensor with wet I/Os and the dry electrical connections. The finished assembled package with the bio-sensor were optically inspected by X-ray CT, X-ray, cross sectioning and SEM. Preliminary results indicate that the complete molded module has an electrical contact, from top-bottom-top, with a resistance of 1-3Ω

Hybrid-mounted micromachined aluminum hotwires for wall shear-stress measurements

In this paper, we present a micromachined metal hotwire anemometer sensor for use in wall shear-stress measurements. We describe its design and fabrication. A novel hybrid assembly method has been developed to make it possible to measure close to the surface without contacting leads interfering with the flow. Experimental results illustrate the behavior and characteristics of this sensor

Hybrid mounted micromachined aluminium hot-wire for near-wall turbulence measurements

We present the first micromachined metal hot-wire anemometer sensor for use in near-wall turbulence measurements. To measure close to the surface without the circuitry interfering with the flow, a novel hybrid assembly of the sensor has been developed. We present the design, fabrication and characteristics of this sensor