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Nano-scale Biological Sensors Background: Nanotechnology is an emerging field whose goal is to develop materials, devices, and sensors with controlled dimensions and properties at the nanometer scale. Properly designed nano-systems can have significant advantages over larger scale systems. Nanotechnology is highly multidisciplinary and is being applied to all areas of science including biology. One interesting biological application of nanotechnology is the sensor. Bio-sensors are transducers used to detect varying biological entities such as proteins, DNA, and viruses. The mechanism of transduction varies, as nano bio-sensors can be fabricated to use electrical, mechanical piezo-electric, or photonic detectors. Biosensors are of extreme interest for point-of-care applications where medical personnel need to know whether a patient is suffering from a number of illnesses within minutes. They are also useful in homeland security scenarios to detect very small concentrations of dangerous pathogens, enabling emergency personnel to provide an immediate and accurate response to any event. The analyte (the substance we are interested in analyzing) in the former scenario is typically some human fluid such as blood, and in the latter a dilute mixture of water vapor and other particles. Problem Statement: In many bio-sensing scenarios, the analyte is bio-hazardous. Therefore, for a commercially viable sensor solution, the probe in contact with the analyte must be inexpensive and disposable. This necessitates the use of radically different processing steps to fabricate traditional semiconductors. Ideally, disposable sensors should be made of plastic or glass, however neither of these materials can be subjected to the extreme temperatures that traditional semiconductors require for processing. A number of novel approaches are therefore required for a disposable, easy to manufacture nano-sensor. It is also necessary to implement significant error-checking and signal conditioning to limit the chance of an incorrect reading. This can be a huge problem for nano-sensors because their sensitivity and therefore signal noise is orders of magnitude greater than normal sensors. Inadequacy of Current Solutions:
Micro-scale sensors suffer a number of important disadvantages versus
nano-scale biological sensors. First, their sensitivity to small
concentrations of biological organisms is greatly reduced. Lieber et al
have demonstrated electrical detection of single virus particles in water with
concentrations as low as parts per 10^17 in a time period of several seconds
with a silicon nano-wire functionalized with antibodies. This
concentration is several orders of magnitude lower than is possible to detect
with a micro-scale sensor. The most obvious advantage with nano-scale sensors is their size. It is possible to design the sensing system with redundancy and error-checking to reduce false positive and negative readings, and to incorporate a multitude of sensors for different agents of interest. It may also be possible to develop an implantable sensor with elements on this scale. Team Members: Kyle Hardin hardinkm@gmail.com Shikha Goyal sgoyal85@gmail.com Faculty Advisor: Dr. Chong Ahn Co-advisor: Mike Rust (PhD student, bioMEMS Research Group) Goal: Design and fabricate a proof-of-concept, disposable biosensor-element using the fabrication process developed in Dr. Ahn's lab.
Develop detection circuitry for low-noise, high-sensitivity operation. Subgoals:
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