Fabrication and C-Reaction Protein Testing of a Piezoresistive Microcantilever Beam Biosensor
Date Issued
2007
Date
2007
Author(s)
Lin, Kuan-Yi
DOI
zh-TW
Abstract
C-reaction protein( CRP ) is becoming one of important biomarkers in cardiovascular disease, myocardial infarction( MI ), and atherosclerosis. Higher concentration of CRP in serum elevates the risk of those diseases. Despite of existing techniques of surface plasmon resonance( SPR ), enzyme-linked immunosorbent assay( ELISA ) and others developed, the present piezoresistive microcantilever biosensors are sensitive, potentially inexpensive, label-free and of ease-of-use in miniaturization.
To be detected, the microcantilevers are placed inside a microfluidic system that has a volume of several ten microliters. As probed biomolecules are transported onto a sensing surface of microcantilevers, specific recognition occurs, resulting in biomolecular conformation change and associated nanomechanic deflection of induced surface stresses. The deflection is mostly detected by an optical lever of detection system. Despite sensitive detection, the entire optical measurement is bulky and hardly aligned in readout system.
For biomolecular recognition, the piezoresistive cantilever is required for operation in a phosphate buffered saline solution or human plasma which is to maintain a specific pH environment of a strong electrolyte. As a result of device electrical insulation to its solution, the piezoresistive cantilever is required to be surrounded by the insulating material to prevent electric leakage and unwanted chemical reaction on the sensing surface. The selected silicon nitride is used to conform to the requirements for the insulting material. The cantilevers are designed in 150 or 200 μm long, 50 μm wide and about 1.4 μm thick. The integrated piezoresistive resistors are 100 μm long, 50 μm wide and 200 nm thick, and the expected resistance is approximately 4 kΩ. Meanwhile, the gold layer (30 nm thick) coated on the cantilever surface is necessary for chemical reaction of biolinker, and thus the sensing surface of specific protein adsorption and its associated recognition. Preliminary result of CRP detection was obtained by this piezoresistive microcantilever. The device is confirmed to be tested in solution environment and thus its preliminary feasibility. More testing is required for further verification in CRP detection.
Subjects
C-反應蛋白
壓阻式微懸臂梁生物感測器
惠司通電橋
C-Reaction Protein
biomolecular recognition
piezoresistive cantilever
SDGs
Type
thesis
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