Effect of potassium present in stratum corneum during non-invasive measurement of potassium in human subjects using reverse iontophoresis

Reverse iontophoresis with the development of flexible electronics: A review

Skin-centric diagnosis techniques, such as epidermal physiological parameter monitoring, have developed rapidly in recent years. The analysis of interstitial fluid (ISF), a body liquid with abundant physiological information, is a promising method to obtain health status because ISF is easily assessed by implanted or percutaneous measurements. Reverse iontophoresis extracts ISF by applying an electric field onto the skin, and it is a promising method to noninvasively obtain ISF, which, in turn, enables noninvasive epidermal physiological parameter monitoring. However, the development of reverse iontophoresis was relatively slow around the 2010s due to the rigidity and low biocompatibility of the applied devices. With the rapid development of flexible electronic technology in recent years, new progress has been made in the field of reverse iontophoresis, especially in the field of blood glucose monitoring and drug monitoring. This review summarizes the recent advances and discusses the challenges and opportunities of reverse iontophoresis.

Sampling of fluid through skin with magnetohydrodynamics for noninvasive glucose monitoring

Out of 463 million people currently with diabetes, 232 million remain undiagnosed. Diabetes is a threat to human health, which could be mitigated via continuous self-monitoring of glucose. In addition to blood, interstitial fluid is considered to be a representative sample for glucose monitoring, which makes it highly attractive for wearable on-body sensing. However, new technologies are needed for efficient and noninvasive sampling of interstitial fluid through the skin. In this report, we introduce the use of Lorentz force and magnetohydrodynamics to noninvasively extract dermal interstitial fluid. Using porcine skin as an ex-vivo model, we demonstrate that the extraction rate of magnetohydrodynamics is superior to that of reverse iontophoresis. This work seeks to provide a safe, effective, and noninvasive sampling method to unlock the potential of wearable sensors in needle-free continuous glucose monitoring devices that can benefit people living with diabetes.