title: Improvement of Depth Profiling into Biotissues Using Micro Electrical Impedance Spectroscopy on a Needle with Selective Passivation.
abstract: A micro electrical impedance spectroscopy (EIS)-on-a-needle for depth profiling (μEoN-DP) with a selective passivation layer (SPL) on a hypodermic needle was recently fabricated to measure the electrical impedance of biotissues along with the penetration depths. The SPL of the μEoN-DP enabled the sensing interdigitated electrodes (IDEs) to contribute predominantly to the measurement by reducing the relative influence of the connection lines on the sensor output. The discrimination capability of the μEoN-DP was verified using phosphate-buffered saline (PBS) at various concentration levels. The resistance and capacitance extracted through curve fitting were similar to those theoretically estimated based on the mixing ratio of PBS and deionized water; the maximum discrepancies were 8.02% and 1.85%, respectively. Depth profiling was conducted using four-layered porcine tissue to verify the effectiveness of the discrimination capability of the μEoN-DP. The magnitude and phase between dissimilar porcine tissues (fat and muscle) were clearly discriminated at the optimal frequency of 1 MHz. Two kinds of simulations, one with SPL and the other with complete passivation layer (CPL), were performed, and it was verified that the SPL was advantageous over CPL in the discrimination of biotissues in terms of sensor output.
authors.affiliation: Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712, Korea. joho@gist.ac.kr.
authors.forename: Joho
authors.initials: J
authors.lastname: Yun
authors.affiliation: Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712, Korea. cs8do@gist.ac.kr.
authors.forename: Hyeon Woo
authors.initials: HW
authors.lastname: Kim
authors.affiliation: Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712, Korea. jonghyun@gist.ac.kr.|School of Mechanical Engineering, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea. jonghyun@gist.ac.kr.
authors.forename: Jong-Hyun
authors.initials: JH
authors.lastname: Lee
mesh_terms: D000818:Animals; D003198:Computer Simulation; D058266:Dielectric Spectroscopy / Q000379:methods*; D017097:Electric Impedance; D004867:Equipment Design; D007091:Image Processing, Computer-Assisted; D055616:Microtechnology / Q000379:methods*; D009339:Needles; D009928:Organ Specificity; D015203:Reproducibility of Results; D034421:Sus scrofa
keywords: biotissues; depth profiling; electrical impedance spectroscopy; hypodermic needle; interdigitated electrodes; selective passivation