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1630738 
Journal Article 
Capacitive micromachined ultrasonic transducers for chemical detection in nitrogen 
Park, KK; Lee, HJ; Yaralioglu, GG; Ergun, AS; Oralkan, O; Kupnik, M; Quate, CF; Khuri-Yakub, BT; Braun, T; Ramseyer, JP; Lang, HP; Hegner, M; Gerber, Ch; Gimzewski, JK 
2007 
Yes 
Applied Physics Letters
ISSN: 0003-6951
EISSN: 1077-3118 
91 
9 
WOS:000249156100148 
The authors present the prototype of a chemical sensor
using a capacitive micromachined ultrasonic transducer array. Each element in the array consists
of a large number of resonating membranes connected in parallel. A five-channel oscillator
circuit operates at the resonant frequency around 6 MHz in this prototype. The surface of the
elements in the array is coated by polymers such as polyallylamine hydrochloride, polyethylene
glycol, and polyvinyl alcohol to detect different chemicals. By measuring shift in oscillation
frequencies due to the mass-loading effect, analytes, e.g., water and isopropanol, with
concentrations around 20 ppbv (parts per 10(9) by volume) range can be detected. (C) 2007
American Institute of Physics.