Simulation and fabrication of SiO₂-based piezoresistive microbridges for chem/biosensors

Abstract

This paper uses finite element design for optimization of piezoresistive silicon covered SiO 2 microbridges. Resistance changes of the microbridge due to the surface stress changes were systematically investigated by varying Si piezoresistor geometries and the boron doping concentrations in silicon. Our simulation results show that the resistance change of the microbridge is directly related to the arcuation of the microbridges and a better R/R response can be obtained with a thinner and narrower silicon piezoresistor. However, the S/N ratio was not significantly affected by the SiO 2 dimensions. A fabrication process of silicon covered SiO 2 microbridges is also reported.

Micro- and nano-structure based oligonucleotide sensors

“…It is believed that microbridges may prove more stable than microcantilevers, although potentially at the expense of reduced sensitivity. To date, microbridges have not been extensively investigated for biosensing applications (Adrega et al, 2006;Lu et al, 2006). The principle strengths of micro-or nano-cantilever-based oligonucleotide sensors are easy functionalisation, ready optimisation through manipulation of the sensor geometry, and scalability, with existing fabrication techniques translating into the preparation of large arrays Ziegler, 2004).…”

Design of an osmotic pressure sensor for sensing an osmotically active substance

“…The doping concentrations affect the piezoresistive coefficient in the [1 1 0] direction for P-type Si. The piezoresistive coefficients in the longitudinal (π l ) and transverse (π t ) directions are 71.8 × 10 −11 Pa −1 and −66.3 × 10 −11 Pa −1 , respectively, and these are assumed to be constant for low doping concentrations (<10 17 cm −3 ) [9,10]. The targeted doping concentration is approximately 4 × 10 18 cm −3 , and it is relatively high, although it will reduce the temperature dependence.…”

“…The material properties of Si and the piezoresistive coefficients for the P-type Si used in this work are listed in table 1 [10,13]. The reference glucose concentration inside the device cavity is kept at 100 mg dL −1 .…”

Design and analysis of MEMS based capacitive pressure sensor for the detection of colon cancer

“…Micro cantilevers have ability to show higher sensitivity [2][3]. Detecting mechanism of smaller scale cantilever biosensor varies as indicated by application [4][5][6]. The capacitive technique gives more sensitivity compared with mechanical stress and piezoresistive structure [7].…”