The study of different pH and chemical surface modification on a piezoresistive microcantilever biosensor
Date Issued
2007
Date
2007
Author(s)
Lai, Yu-Cheng
Abstract
With the advancement of technology, relevant disease detection and health examination are growing with prosperity. However, most of the biological sensors are still using chemical or fluorescent markers as detectors, which are having lower sensitivities. This work utilized single-beam micro-cantilever biosensor for measuring biological signal, and for targeting the development of a more sensitive detecting method. n most of the studies double-beam micro-cantilever biosensors are constructed as two resistances of the Wheatstone bridge and one is taken as reference to compensate for background noises resulting from fluid field and temperature change. But this work discovered that the difference of surface materials of the two beams may result in ignoring effects of chemical reactions to biological signals. In the present study we select single free-beam devices as measuring mechanism to maintain the temperature change in 5oC. Utilizing immune analysis, the beam surface was treated by gold-sulfur bonding to explore the effect of surface modification (HS-(CH2)7-COOH) on micro cantilever beams. The results show that pH does make effect on the cantilevers at the values of 2, 3, 11, 12, while pH does not make effect on cantilevers at pH values between 4 to 10. The signals increase at smaller pH values and decrease at larger pH values. For results mentioned above, the unwanted signal arisen from the single-beam piezoresistive cantilever response to varying pH value can be eliminated in the detection of biological for future reference. We have successfully discovered the response to varying pH value effect on the single-beam micro cantilever and measured the decline of output signals after chemical adsorption.
Subjects
piezoresistive microcantilever
pH
chemical surface modification
Type
thesis
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