Apple Watch blood glucose monitoring can work like this …

Yesterday’s report that Apple Watch could see the blood glucose monitoring when the Series 7 is released this year has caused excitement and skepticism.

Excitement because it can provide a much easier method of monitoring blood sugar levels than current devices, which require a pin prick sample. Skepticism because non-invasive measurement has been a goal for many years, with very limited success to date. The closest to us so far is a sensor with rice grain size embedded in the skin, which can then be read without further protruding the skin …

Traditional blood glucose monitors require the patient to use a pin device to draw a drop of blood and transfer it to a test strip, which is then read by a machine. The process is not ideal: it is very slightly painful, somewhat cumbersome and requires a steady supply of test strips.

For this reason, many companies have tried to develop non-invasive monitors – that is, those that do not require a drop of blood.

One form of non-invasive measurement in development uses the thin skin flap between thumb and forefinger.

The glucose levels are extracted by a non-invasive technique that transmits low-power radio waves through a portion of the human body, such as the area between the thumb and forefinger. These areas have adequate blood supply and are thin enough for the waves to move through the tissue. These signals are then received by a sensor on the opposite side of the GlucoWise device, where the data on the properties of the blood in the flesh are collected and analyzed.

But as the explanation says, it only works because the skin there is very thin. How Can An Apple Watch Measure Blood Glucose Through The Pulse?

The answer may lie in an approach described in Earth in the summer of last year. A skin tag – a bit like an RFID – is glued to the skin and then validated by a reader embedded in the Apple Watch.

This paper reports an extremely sensitive, non-invasive sensor for real-time glucose monitoring of interstitial fluid. The structure consists of a disk-free label sensor that can be pasted over the patient’s skin and a reader that can be embedded in a smartwatch.

The mark sensor is switched on by the established electromagnetic coupling between the marker and the reader and its frequency response is reflected in the spectrum of the reader in the same way. The label sensor consumes no power, as there is no requirement for an active read or communication path on the side of the label […]

The observation element itself is only a metal track that can be easily glued to the patient’s skin and can be replaced at a very low cost. […]

When measuring changes in glucose concentrations within salt that replicate interstitial fluid, the sensor was able to detect glucose with an accuracy of 11 mM / l over a physiological range of glucose concentrations at 38 kHz from the resonant frequency shift. This high sensitivity is achieved due to the proposed new design and extensive field concentration on the label.

It works by measuring the shift in radio frequency. This shift is proportional to the relative percentages of water and glucose in the blood.

This frequency is chosen because there is a significant difference between water, as the main material in interstitial fluid, and the saturated glucose solution permittivity, while their loss factors are still small, and therefore to measure with this frequency, results in a significant frequency shift. and thus the device sensitivity.

We illustrated yesterday how the results can be displayed on the Watch.

There are also some infrared approaches in development, which could possibly work with existing Apple Watch models, but the above approach looks more promising in terms of accuracy.

All this, however, remains very speculative. The method needs to be evaluated and approved for use, and it appears that this technology is at a very early stage of the process. Although I think we’ll probably see it in the Apple Watch at some point, the timing seems tight for a Series 7 version.

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