PEDOT coated microneedle towards electrochemically assisted skin sampling

Skin sampling is a diagnostic procedure based on analysis of extracted skin tissue and/or observation of biomarkers in bodily fluid. Sampling using microneedles (MNs) that minimize invasiveness are gaining attention over conventional biopsy/blood lancet. In this study, new MNs for electrochemically assisted skin sampling are reported, specifically tailored for combined skin tissue biopsy and interstitial fluid (ISF) extraction. To overcome risks associated with using metal MNs, a highly electroactive, mechanical flexible, and biocompatible organic conducting polymer (CP) coated onto plastic is chosen as an alternative. Two different variants of doped poly(3,4-ethylenedioxythiophene) are coated on polymethyl methacrylate and used in combination as a MN pair with subsequent testing via a variety of electrochemical techniques to (i) give real-time information of the MN penetration depth into the skin, and (ii) yield new information about the various salts present in the ISF. The MN skin sampler shows an ability to extract ions from the ISF when analyzed using X-ray photoelectron spectroscopy. This added chemical information in conjunction with existing biomarker analysis increases opportunity for disease/condition detection. For example, in the case of psoriasis information about the salt concentration in the skin is invaluable to combine with pathogenic gene expression for diagnosis. Refereed/Peer-reviewed