Photonics and Electronics Research Lab
Recent reports have shown that devices based upon silicon nanowire building blocks can be fabricated into high density, ultrasensitive, chemical and biological sensors. Top-down method allows silicon nanowire to be fabricated using standard CMOS techniques. Antibodies conjugated to the surface of the nanowires provide specific binding sites for target antigens which represent the analyte of interest. When an antigen attaches to the antibody on the nanowire, the net charged on the antigen displaces free carriers in the nanowire channel, changing its conductance. To date, detection methods have been based upon directly measuring the change in DC conductance. This is difficult and requires sensitive low noise amplifiers and high resolution Analog to Digital Converters, which is not ideal for low cost and highly integrated systems. There has been reported that the AC-transfer function of silicon nanowires resembles that of a high pass filter. As molecules with a higher net charge attach and displace more charge carriers within the nanowire channel, the filter’s corner frequency decreases. Based on this property, our project aims to build a low cost real-time antigen detection system using silicon nanowires.
Prof Christina Lim
Director, Photonics and Electronics