title: An implantable bioimpedance monitor using 2.45 GHz band for telemetry.
abstract: This paper describes a multi-frequency single-channel electrical implantable bioimpedance monitor (35 mm × 35 mm × 10 mm, weight 52 g) powered by a NiMH battery. By using the tetrapolar method and injecting 10 µA(peak), the monitor is capable of measuring at 14 different frequencies, from 100 Hz to 200 kHz. It contains a ZigBee transceiver to monitor the measurements performed, and has an embedded memory for backing up the data. RC networks and in-situ heart excised tissues were used to test the system. When measuring a full spectrum every 5 min, 35 days of autonomy are possible due to the low power consumption of the monitor. Temperature drift was estimated by short-term and long-term measurements. Temperature cycling was used to measure modulus and phase angle stability. The result was a very low effect on a modulus decrease of 2.34 Ω, with respect to an impedance of 322 Ω, at 100 Hz and a phase angle increase of 1.1°, at 200 kHz. In addition, measurement errors were bigger at low frequencies because of the high impedance of the electrodes used, which was higher than 10 kΩ at frequencies below 1 kHz.
authors.affiliation: Electronic Engineering Department, Technical University of Catalonia, Jordi Girona 1-3 Edifici C4, 08034 Barcelona, Spain. paco.bogonez@gmail.com
authors.forename: Paco
authors.initials: P
authors.lastname: Bogónez-Franco
authors.forename: Lexa
authors.initials: L
authors.lastname: Nescolarde
authors.forename: Carolina
authors.initials: C
authors.lastname: Gálvez-Montón
authors.forename: Ramon
authors.initials: R
authors.lastname: Bragós
authors.forename: Javier
authors.initials: J
authors.lastname: Rosell-Ferrer
mesh_terms: D000818:Animals; D003198:Computer Simulation; D017097:Electric Impedance; D004560:Electricity; D004566:Electrodes; D006801:Humans; D066298:In Vitro Techniques; D008991:Monitoring, Physiologic / Q000295:instrumentation*; D019736:Prostheses and Implants; D011846:Radio Waves; D012756:Sheep; D013686:Telemetry / Q000295:instrumentation*; D013696:Temperature; D013997:Time Factors