Yesterday’s report that we may see the Apple Watch’s blood glucose monitoring when the Series 7 launches this year has generated excitement and skepticism.
Excitement because it could provide a much easier method of monitoring blood sugar levels than current devices, which require a blood sample per needle stick. Skepticism because noninvasive measurement has been a goal for many years, with very limited success so far. The closest we have come so far is a sensor the size of a grain of rice embedded in the skin that can then be read without any additional perforation in the skin …
Traditional blood glucose monitors require the patient to use a needle stick device to take a drop of blood and transfer it to a test strip, which is read by a machine. The process is not ideal: it is a little painful, somewhat complicated and requires a constant supply of test strips.
For this reason, many companies have been trying to develop non-invasive monitors – that is, that do not require a drop of blood.
A developing form of non-invasive measurement uses the thin skin flap between the thumb and forefinger.
Glucose levels are extracted by a non-invasive technique that transmits low-power radio waves through a section of the human body, such as the area between the thumb and forefinger. These areas have adequate blood supply and are thin enough for waves to pass through the tissue. These signals are then received by a sensor on the opposite side of the GlucoWise device, where data on the characteristics of the blood within the meat are collected and analyzed.
But, as the explanation says, this only works because the skin there is very thin. How can an Apple Watch measure blood glucose by the wrist?
The answer may lie in an approach described in Nature last summer. A skin tag – a bit like RFID – is glued to the skin and powered by a reader built into the Apple Watch.
This document reports a highly sensitive, non-invasive sensor for real-time monitoring of interstitial fluid glucose. The structure consists of a chipless tag sensor that can be glued to the patient’s skin and a reader, which can be embedded in a smartwatch.
The tag sensor is energized through the electromagnetic coupling established between the tag and the reader and its frequency response is reflected in the spectrum of the reader in the same way. The tag sensor consumes zero energy, as there is no requirement for any active reading or communication circuit on the tag side […]
The sensor element itself is just a metallic trace that can be simply glued to the patient’s skin and can be replaced at an extremely low cost […]
By measuring changes in glucose concentrations in the interstitial saline replication fluid, the sensor was able to detect glucose with an accuracy of ~ 1 mM / l in a physiological range of glucose concentrations with 38 kHz of the change in frequency of resonance. This high sensitivity is obtained as a result of the proposed new design and the extended field concentration on the label.
It works by measuring the change in radio frequency. This change is proportional to the relative percentages of water and blood glucose.
This frequency is selected because there is a considerable difference between water, as the main material in the interstitial fluid, and the permissiveness of the saturated glucose solution while its loss factors are still small and therefore measuring at this frequency will result in a change in frequency. significant and therefore the sensitivity of the device.
Yesterday we illustrated how the results can be displayed on the clock.
There are also some infrared approaches under development that could work with existing Apple Watch models, but the approach above looks more promising in terms of accuracy.
All of this remains highly speculative, however. The method would need to be evaluated and approved for use and it appears that this technology is at a very early stage in this process. Although I think we will probably see this on the Apple Watch at some point, the time seems tight for the launch of the Series 7.
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