Sweat and interstitial fluid can also be obtained by non-invasive iontophoresis. This technique can apply a mild electric current between two skin wearing electrodes to induce ion migration in sweat or interstitial fluid without damaging the skin or removing blood, and can be carried out when the human body is resting. Cygnus has demonstrated for the first time a wrist wearable device based on a reversed-phase ion electroosmosis sensor called GlucoWatch biographer. This FDA certified device can monitor glucose in stromal fluid six times in an hour, continuously working for more than 12 hours.

Because the components of interstitial fluid diffuse directly from the capillary endothelium, the glucose level in interstitial fluid is closely related to blood glucose. The glucose biosensor installed on the skin can be used to measure the glucose extracted from ISF easily. However, the device has a warm-up time of up to 2-3 hours; an invasive blood glucose meter is still needed to calibrate the device; and, more importantly, it has been reported that inverse iontophoresis can irritate the skin, and the product was withdrawn from the market in the early 21st century.

After that, the research team of the Department of Nano Engineering at the University of California, San Diego developed an ion electroosmosis platform, which was initially called the flexible temporary tattoo sensor. The electrode used for reverse ion electroosmosis and glucose biosensor electrode are made by screen printing. This concept platform solves several problems of GlucoWatch biographer. First of all, by reducing the applied iontophoresis current and glucose detection potential, the stimulation of reversed iontophoresis on skin was reduced. Secondly, one-time screen printing reduces the price of the equipment. Finally, it can be easily fixed to the skin surface without interfering with the wearer's movement.

This device has been verified successfully, which shows the potential of disposable glucose sensing platform based on ion electroosmosis applied to wearable devices. However, the device lacks electronic integration and needs to be validated for long-term continuous monitoring applications. Tsinghua University, in cooperation with the General Hospital of the air force, has designed a new sensor for wearable equipment, which has the transfer function of hyaluronic acid with positive charge, so as to accelerate the transfer of glucose to the skin surface and improve the efficiency of glucose sampling in interstitial fluid.

These glucose sensors based on iontophoresis make full use of the close relationship between glucose and blood glucose in interstitial fluid, and the ability of iontophoresis to sample from interstitial fluid when human body is still. However, it is difficult to control the efficiency of glucose extraction by iontophoresis, which may lead to the inconsistent volume of interstitial fluid and the change of glucose concentration.