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    Item type:Publication,
    Symmetrical poly MUMPs-based piezoresistive microcantilever sensors with on-chip temperature compensation for microfluidics applications
    (2008-05-01)
    Tuantranont, Adisorn
    ;
    Lomas, Tanom
    ;
    Jaruwongrungsee, Kata
    ;
    Jomphoak, Apichai
    ;
    Wisitsoraat, Anurat
    Microelectromechanical systems (MEMS)-based cantilever beam sensors for microfluidics applications with on-chip temperature sensors for temperature drift compensation were developed. The stress induced on gold surface with polysilicon piezoresistive sensing is demonstrated. In principle, adsorption of biochemical species on a functionalized surface of the microfabricated cantilever will cause surface stress and, consequently, cantilever bending. The sensing mechanism relies on the piezoresistive properties of the doped polysilicon wire encapsulated in the beam. The beam is constructed through multiusers MEMS Process (PolyMUMPs) foundry with postprocessing silicon etching. Bending analysis is performed so that the beam tip deflection can be predicted. The piezoresistor designs on the beams were varied, within certain constraints, so that the sensitivity of the sensing technique could be measured by external read-out circuit. The mass detection of 0.0058-0.0110 g is measured by the beam resistor series as a balanced Wheatstone bridge configuration. The voltage output of the bridge is directly proportional to the amount of bending in the MEMS cantilever. The temperature dependency and sensor performance have been characterized in experiments. Compensation by resisters on the substrate significantly reduces the temperature dependence. © 2008 IEEE.
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    Item type:Publication,
    Design consideration and finite element modeling of MEMS cantilever for nano-biosensor applications
    (2005-01-01)
    Klaitabtim, Don
    ;
    Tuantranont, Adisorn
    This work has focused on the design and finite element modeling of a MEMS cantilever beam for biosensor applications. The stress induced on gold surface with polysilicon piezoresistive sensing is demonstrated. In principle, adsorption of biochemical species on a functionalized surface of the microfabricated cantilever will cause a surface stress and consequently the cantilever bending. The sensing mechanism relies on the piezoresistive properties of the polysilicon wire encapsulated in the beam. The beam is constructed and bending analysis is performed so that the beam tip deflection could be predicted. The twelve independent beams were combined onto a single chip. The piezoresistor designs on the beams were varied, within certain constraints, so that the sensitivity of the sensing technique could be studied. The chip was laid out using Tanner L-edit and the design rules of the MUMPs process were followed. The device model was simulated using CoventorWare™, a commercial finite element analysis (FEA) tool designed specifically for MEMS applications. Finally, the MEMS cantilever beam was operated and caused increment in tip deflection due to biochemical adsorption on the gold surface. ©2005 IEEE.