The ability to quickly and reliably detect minute changes in
environmental conditions,including the presence of chemical, biological or other
physical threats within a low-cost, miniaturized package would have broad impact
across a variety of application. The presence or absence of specific chemicals
and toxic gases in air, harmful compounds in foods and water, and early alert of
trace amounts of explosives or chemical and biological warfare agents all
require reliable and sensitive detection technologies.
ASU scientists have developed a miniaturized device for
sensing a variety of chemical, biological and physical phenomenon based on a
common tuning fork technology. The sensor consists of an array of
microfabricated quartz tuning fork based sensing elements. Each sensor uses a
polymer wire stretched across the two prongs of a tuning fork or simply a
polymer-coated tuning fork. In the former case, when the fork is set to
oscillate, the polymer wire is stretched and compressed by the two prongs. In
the later case, the adsorption changes the effective mass of each tuning fork
which is detected with 10 pg/mm2 sensitivity. Interaction of a chemical or
biological analyte with the polymer causes stretching and compressing forces in
the wire, which is detected by the quartz tuning fork with pN force sensitivity.
The polymer may also absorb energy from radiation or convection. Using the
tuning fork sensors, ASU scientists have successfully detected many chemical and
biological analytes, and have more recently demonstrated its utility as a
thermal / IR sensor.
There are a myriad of potential commercial applications for
- Environmental / Health Hazards Detector-Air pollutants,
noxious and dangerous chemicals (e.g. formaldehyde), gas leaks, food analysis
- Infrared/Thermal Detection or Imaging
- Environmental Conditions Sensor – Can sense small changes
in temperature and other environmental conditions.
- Chemical Weapons Detector – Homeland Security issues
- Breath Analysis – alcohol, disease biomarkers, such as,
nitric oxide for asthma diagnosis and drug dose setting; ketones for
management of diabetes; bacterial infections; etc.
Benefits and Advantages
- High Sensitivity: The symmetric arrangement of the two
prongs leads to sharp resonance and differential amplification, which is
responsible for the extremely high sensitivity
- High Thermal and Mechanical Stability: microfabricated
quartz tuning forks have near zero thermal coefficient and rigid structure
- Tunable Specificity: specificity is achieved by tuning
the chemical compositions of the polymers
- Fast Response: The response time of the detector is as
fast as ms
- Low Cost and Portable Device: Low cost, microfabricated
quartz tuning fork technology, easily drive and detect many sensing elements
simultaneously with a simple circuit.