A Bioimpedance-based Transducer for Insulin Bioavailability Assessment after Subcutaneous Administration

The prototyping and metrological characterization of a transducer for monitoring insulin bioavailability after subcutaneous administration is presented. The measurement of local impedance allows to assess the disappearance of insulin from the injection site and thus to indirectly estimate its bioavailability. The device is designed to replace the impedance meter of a noninvasive and painless instrument, namely the Insulin Meter, already presented by the authors in previous studies. In the first part of the article, the prototyping of the hardware, firmware, and software is discussed. Then, the metrological characterization in the laboratory (on passive electronic components), in-vitro (on eggplants), and in-vivo (on a human volunteer) is reported. The results showed sensitivity compatible with the previous version of the bio-impedance meter. Instead, the repeatability improved by an order of magnitude. Finally, the impedance phase can be performed (unlike the previous device) and exhibit a smooth trend as the amount of drug under the skin changes.