A Bioimpedance Meter to Measure Drug in Transdermal Delivery

An on-chip instrument for measuring ex post the drug actually released by transdermal delivery is proposed. The volume of a drug conveyed through the skin is assessed by measuring the bioimpedance locally before and after delivery. In therapeutic applications, the instrument can provide a low-cost and clinically portable solution. In the first part of this paper, the concept and physical design of the instrument as well as details about its realization and operations are illustrated. Then, the metrological characterization, using injection as a reference subcutaneous transfer of a known volume of drug, is reported in laboratory,
in vitro
on eggplants and
ex vivo
on pig ears. Results of resolution, short-term stability, interindividual tissue reproducibility, sensitivity, repeatability, and linearity point out noteworthy scenarios of clinical applications.