Title :
A passive humidity monitoring system for in situ remote wireless testing of micropackages
Author :
Harpster, Timothy J. ; Hauvespre, Sébastien ; Dokmeci, Mehmet R. ; Najafi, Khalil
Author_Institution :
Dept. of Electr. Eng. & Comput. Sci., Michigan Univ., Ann Arbor, MI, USA
fDate :
2/1/2002 12:00:00 AM
Abstract :
Reports a small passive wireless humidity monitoring system (HMS) for continuous remote monitoring of humidity changes inside miniature hermetic packages, presents its application in determining hermeticity of an implantable biomedical package, and presents long-term performance results obtained from packages implanted in guinea pigs. This 7×1.2×1.5 mm3 system consists of a high-sensitivity capacitive humidity sensor that forms an LC tank circuit together with a hybrid coil wound around a ferrite substrate. The resonant frequency of the circuit changes when the humidity sensor capacitance changes in response to changes in humidity. The HMS can resolve humidity changes of ±2.5% RH over a 2-cm range. The resolution is sufficient enough to monitor internal package humidity for either in vitro or in vivo testing
Keywords :
biomedical telemetry; capacitive sensors; humidity measurement; microsensors; packaging; prosthetics; seals (stoppers); 2 cm; LC tank circuit; capacitive humidity sensor; guinea pigs; hybrid coil; implantable biomedical package; in vitro testing; in vivo testing; micropackages; miniature hermetic packages; passive humidity monitoring system; remote wireless testing; resonant frequency; Biomedical monitoring; Biosensors; Capacitive sensors; Circuits; Coils; Humidity; Packaging; Remote monitoring; Sensor systems; Wounds;
Journal_Title :
Microelectromechanical Systems, Journal of
