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

Volume

11

Issue

1

fYear

2002

fDate

2/1/2002 12:00:00 AM

Firstpage

61

Lastpage

67

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;

fLanguage

English

Journal_Title

Microelectromechanical Systems, Journal of

Publisher

ieee

ISSN

1057-7157

Type

jour

DOI

10.1109/84.982864

Filename

982864