(Invited) Nanotechnology for Biosensing Applications

Sensor related research has greatly increased over the last two decades due to the need for technology and devices for health and environmental monitoring as well as for biological warfare detection.  New developments in biosensor design are crucial as these devices play important roles in daily life. This research work focuses on the development of sensors including microelectromechanical systems (MEMS) sensors and glucose biosensors that are integrated with advanced nano-materials and bio-coatings to create novel devices that are highly sensitive, inexpensive, accurate, and reliable.

More specifically, this paper presents a device based on electrochemical sensing using a working electrode with bio-functionalized zinc oxide (ZnO) nanorods.  Among all metal oxide nanostructures, ZnO nano-materials play a significant role as a sensing element in biosensors due to their properties such as high isoelectric point (IEP), fast electron transfer, non-toxicity, biocompatibility, and chemical stability. Further, the diameter of these nanostructures is usually comparable to the size of the biological and chemical species being sensed which is beneficial in generating signals that interface well with macroscopic instruments and have high device sensitivity.  The nanorods were immobilized with glucose oxidase (GOx) because of its stability and high selectivity to glucose.  The sensor was characterized for electrical response for the evaluation of the bio-functionalization, sensitivity and response time and yielded a linear range of 0.1mM-10.6mM, sensitivity of 18.15μA cm^-1 mM^-1and a limit of detection of 0.1mM

In addition, a MEMS sensor that incorporates a lead zirconate titanate (PZT) film will be presented.  For this device the piezoelectric properties of the PZT are exploited to produce sensors that perform optimally for mass sensing applications for sensing biochemical agents.  The sensor is designed to operate as a thin-film bulk acoustic resonator (TFBAR) whereas a piezoelectric is sandwiched between electrodes and senses a change in mass by measuring a change in resonance frequency. The effect of the PZT thickness on device resonance is also presented. The TFBAR sensor consists of 150 nm of PZT, 150nm of silicon dioxide, the silicon substrate, titanium/platinum bottom electrodes, and aluminum top electrodes.  The top electrodes are segmented to increase the sensitivity of the sensor.  The resonance frequency of the device is 3.2 GHz.  This research involves master’s and undergraduate level students.  Thus, the challenges as well as best practices in incorporating beginning-level researchers will also be presented.