DNA hybridization measurement by self-sensing piezoresistive microcantilevers in CMOS biosensor

Understanding the mechanism of how biological reactions produce mechanical loadings is fundamental to biomedical developments. A CMOS biosensor chip is developed to measure in situ the induced surface stress change by DNA hybridization. For 20-mer thiol-modified single stranded DNA (ssDNA), the mechanism of ssDNA attached to gold surface via a sulfur-gold linkage can be investigated by using the Langmuir adsorption model. Experimental results indicate that the immobilization response is less than I s, the total number of ssDNA molecules on the cantilever is about 3 x 10(11), and the induced surface stress is 0. 15 N/m. The surface stress sensitivity of the sensor is about 3.5 x 10(-5) m/N. The estimated adsorption rate of the ssDNA is 0.005 s(-1). The biosensor is capable of discriminating complimentary molecular targets and thus may provide a powerful platform for high throughput real-time analysis of DNA. (c) 2007 Elsevier B.V. All rights reserved.