Electrical impedance spectroscopy for biotissue differentiation using bipolar electrodes positioned at the end of a hypodermic needle

An EoN (Electrical impedance spectroscopy-On-a-Needle) with bipolar interdigitated electrodes at the very end of a hypodermic needle has been introduced. The device can be utilized to analyze the electrical impedance of biotissues for the purpose of discriminating between tissues prior to biopsy. A flexible photomask and photoresist spray coating were employed in the lithography process to realize the electrode pattern on the round surface of the needle. To evaluate the discrimination capability of the EoN, the impedance of the leg fat and muscle from a slaughtered chicken was measured over the frequency range 10 kHz to 1 MHz. The resistance and reactance were classified into two groups, which was in good agreement with the reported permittivity of fat and muscle tissues from bovines.