The ability to detect bio-molecule at ultra-low concentrations (e.g. atto-molar) will enable the possibility of detecting diseases earlier than ever before. A critical challenge for any new bio-sensing technology is to optimize two metrics --- shorter analysis time, and higher concentration sensitivity in clinically relevant small volumes. Moreover, practical considerations are equally important: simplicity of use, mass producible (low cost), and ease of integration within the clinical structure. Compared with other methods, nano-electro-mechanical system (NEMS) based bio-sensors are promising in clinical diagnostics because of their extremely high mass sensitivity, fast response time and the capability of integration on chip. We have demonstrated a low concentration DNA (atto-molar sensitivity) optically interrogated ultrasonic mechanical mass sensor, which has ordered nanowire (NW) array on top of a bilayer membrane. This method represents a mass-based platform technology that can sense molecules at low concentrations, which could be useful for early-stage disease detection. We can develop this sensor further to measure an array of biomarkers (e.g. DNA or proteins), by providing both the needed specificity and sensitivity in physiological disease (e.g. cancer) detection.
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