title: Measuring bioimpedance in the human uterine cervix: towards early detection of preterm labor.
abstract: We have created a bioimpedance probe designed to detect subtle changes in human cervical tissue composition in vivo, and thereby detect the onset of cervical remodeling in a noninvasive manner sooner than existing clinical methods allow. Our cervical bioimpedance measurement device, which can be used during a routine pelvic examination, is composed of a contoured probe with disposable tip and, within the probe's handle, a bioimpedance sensor equipped with an integrated chip capable of generating sinusoidal voltage of varying frequencies. A constant force spring assures consistent measurements through a range of contact forces applied. An activation switch allows the operator to control the application of current. The sensor can be synchronized with a computer data storage and analysis system, which interfaces with the device. With the probe placed in contact with a collagen gels of varying concentration, the relationship between measured bioimpedance and collagen concentration is verified to be positive exponential (R/sup 2/=0.94) and repeatability in saline solution showed that measurements varied by less than +/-10% over 20 trials. Finally, a variety of user-applied forces showed that impedance values plateau when forces exceed 1N.
authors.affiliation: Dept. of Biomed. Eng., Johns Hopkins Univ., Baltimore, MD, USA.
authors.forename: Y S G
authors.initials: YS
authors.lastname: Hoe
authors.forename: Edith D
authors.initials: ED
authors.lastname: Gurewitsch
authors.forename: A
authors.initials: A
authors.lastname: Shaahinfar
authors.forename: Elbert S
authors.initials: ES
authors.lastname: Hu
authors.forename: Somponnat
authors.initials: S
authors.lastname: Sampattavanich
authors.forename: Melanie
authors.initials: M
authors.lastname: Ruffner
authors.forename: Kenny H S
authors.initials: KH
authors.lastname: Ching
authors.forename: Robert H
authors.initials: RH
authors.lastname: Allen