Micro-needle implantable electrochemical oxygen sensor: ex-vivo and in-vivo studies

Oxygen is vital for energy metabolism in mammals and the variability of the concentration is considered a clinical alert for a wide range of metabolic malfunctions in medicine. In this article, we describe the development and application of a micro-needle implantable platinum-based electrochemical sensor for measuring partial pressure of oxygen in intramuscular tissue (in-vivo) and vascular blood (ex-vivo). The Pt-Nafion® sensor was characterized morphological and electrochemically showing a higher sensitivity of -2.496 nA/mmHg (-1.495 nA/μM) when comparing with its bare counterpart. Our sensor was able to discriminate states with different oxygen partial pressures (pO₂) for ex-vivo (blood) following the same trend of the commercial gas analyzer used as standard. For in-vivo (intramuscular) experiments, since there is not a gold standard for measuring pO₂ in tissue, it was not possible to correlate the obtained currents with the pO₂ in tissue. However, our sensor was able to detect clear statistical differences of O₂ between hyperoxia and hypoxia states in tissue.