Articles by Joho Yun in JoVE
Fabrication of Fine Electrodes on the Tip of Hypodermic Needle Using Photoresist Spray Coating and Flexible Photomask for Biomedical Applications Joho Yun1, Jinhwan Kim2, Jong-Hyun Lee1,2 1Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology (GIST), 2School of Mechanical Engineering, Gwangju Institute of Science and Technology (GIST) The fabrication method for fine interdigitated electrodes (gap and width: 20 µm) at the tip of a hypodermic needle (diameter: 720 µm) is demonstrated using a spray coating and flexible film photomask in the photolithography process.
Other articles by Joho Yun on PubMed
Improvement of Depth Profiling into Biotissues Using Micro Electrical Impedance Spectroscopy on a Needle with Selective Passivation Sensors (Basel, Switzerland). | Pubmed ID: 28009845 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.