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  • Writer's pictureSubir Biswas

Glucose sensor - A Revolutionary sensor for smartwatch | Tech-Knowledge

A biggest question is now that can smartwatches measure blood sugar or Glucose level in blood?

The simple answer is yes; the very first diabetes wristwatch concept introduced in 2001 (20 years ago): the GlucoWatch G2 Biographer, an early attempt at non-invasive glucose monitoring (meaning it took readings without penetrating the skin). Despite gaining FDA approval at the time, that product unfortunately failed and was discontinued in 2007.

There are many ongoing attempts to create a viable wrist-based non-invasive glucose monitor, but none have taken a foothold to date. One of the leading brands in this area is the K’Watch Glucose (from PKVitality) which is Discreet and Painless.

K’Watch Glucose is a CGM (Continuous Glucose Monitor) device that will track your glucose level continuously throughout the day and night. Check your sugar levels discreetly by simply glancing at the watch. The glucose trend and history graphs will help you to improve your glucose level control.

Underneath the watch, you will find the disposable K’apsul, using SkinTaste® technology. K’apsul will consist of an array of micropoints and biosensors that will measure glucose painlessly through the skin. K’apsul will be held in place with a hypoallergenic adhesive patch. The patch will be easily removed and replaced after 7 days of use. Additionally, it can measure the heart rate and steps as well.

What is Blood Glucose sensor or Blood Sugar sensor

It all started with Diabetes. It is a lifelong condition that causes a person's blood sugar level to become too high. There are 2 main types of diabetes:

  • Type 1 diabetes – where the body's immune system attacks and destroys the cells that produce insulin.

  • Type 2 diabetes – where the body does not produce enough insulin, or the body's cells do not react to insulin.

OK, no more details, I'm not a medical practitioner with vast knowledge on this topic. If you want to know more, see the details in This topic is about the sensors which can detect the blood sugar and their process and upcoming development on the electronics.

The Different Types of Glucose Sensors

Glucose or sugar sensors come in either a discrete form (blood glucose meter test strips) or wearable form (a continuous glucose monitor). Although the form factors look different to the user, both types of glucose sensors use similar detection methods. For example, a glucose oxidase biosensor could be in the form of a test strip or a wearable CGM (continuous glucose monitor) sensor.

Blood Glucose Sensors

Blood glucose meters are one of the oldest and most common methods for testing glucose. These devices use enzyme-coated test strips that are manufactured with a precise amount of specific enzymes that can only react to one blood sample. Because of this, test strips are intended for single use and cannot be reused. When inserted into the blood glucose meter and after receiving a blood sample, the test strip communicates with the glucose meter which calculates the amount of glucose in the blood and displays the result on the meter’s screen.

Continuous Glucose Sensors

A continuous glucose monitor or CGM uses a filament coated in glucose sensing enzymes to detect glucose in the interstitial fluid (the fluid between your cells). As a wearable sensor, a CGM automatically detects and measures glucose levels 24 hours a day. A CGM sensor can be used continuously for several days or weeks — the exact duration will vary by manufacturer.

Implantable CGM sensor options offer months-long wear, as they are embedded below the skin in a larger capsule, versus the thinner filament in other CGM sensors. The sensor then works with a transmitter that sits above the skin to send data to a receiver or smart device. The transmitter allows you to wirelessly view your current glucose level and trends. And you can be notified when it’s time to replace the sensor.

How and Where are CGM Sensors Inserted?

With the aid of a needle, the sensor is inserted under your skin. Needle-free options — like the long-wear WaveForm CGM — are also available to reduce complications and minimize pain from insertion.

The recommended areas for insertion most commonly include the abdomen or back of the arm, but the CGM manufacturer will provide exact recommendations to where their product should be placed. To ensure that the sensor remains in place, an adhesive patch (like a BAND-AID®) holds the sensor to your skin.

The brand very popular in this region is Dexcom. We can credit San Diego-based CGM market leader Dexcom with pioneering the ability to view glucose data on a smartwatch. The company first enabled limited Apple Watch connectivity in April 2015, and later expanded that for all personal use of its G5 model in March 2016 and the G6 model once launched in 2018. Now, the Dexcom G6 mobile app is compatible with both Apple and Android watches with various watch faces. It displays your current glucose number and arrow trend, as well as graphs for hourly basis. Anytime you wake up the Apple or Android watch, it syncs with the current CGM data from the app running on your iPhone or Android phone. However, the discreet sensor is slim and water resistance and needs to replace at every 10 days interval.

Glucose sensor - A Revolutionary sensor for smartwatch
Image Source: Dexcom

Blood Sugar Sensor on a smartwatch or Apple watch

There was a rumor that Apple is going to introduce a new hardware to sense the blood sugar or glucose sensor in Apple watch series 7. But Apple disappointed all fans when they announced Apple 7 with no hardware change except the processor.

According to the ET News Samsung will also introduce blood sugar monitoring in its upcoming Galaxy Watch 4 which will work in a no-blood sampling capacity. Rather than requiring users to prick their skin, an advanced optical sensor will be used to detect the level of glucose in the body. So, it makes sense that the Apple counterpart would follow suit sooner rather than later. By adding a blood sugar sensor to the Apple Watch, users would be able to test, diagnose, and treat their condition without seeing a doctor. Apple has already secured a patent for the technology and has reportedly been focusing on testing and reliability and stability improvements for the past 12 months. Right now, we don’t know whether the existing infrared sensor on the Apple Watch will be able to act as a blood glucose detector, but considering the company is keen to shrink the chassis of the device to create something even thinner and more attractive, it could be that the sensor is upgraded to serve multiple purposes to maintain the wearable shape.

According to Patently Apple during 2018, Apple applied for a patent that 'Secret Apple Team' is working on for Diabetes testing. They planned to use absorption spectroscopy to obtain noninvasive blood sugar readings. The technology could even use terahertz electromagnetic radiation instead of using light to pass through the body to detect “gas, health/quality of liquid or solid materials.” Apple identified a potential issue with the new Apple Watch technology, suggesting that it could result in the Watch losing water resistance. Experts have also suggested that the technology could mean the Apple Watch battery is drained even faster, but Apple could likely outrun this by adding in a larger battery pack or even introducing a new chip that’s more efficient and can handle multiple processes at once.

However, in 2021 Apple won the patent for an 'integrated photonics device' that can be used for monitoring blood glucose. Apple tied up with a company named Rockley Photonics, who designs silicon photonic sensors for monitoring a person’s blood using infrared light. The company describes its technology as “significantly more accurate” than LED sensors commonly used in smart wearables. The sensors are designed to continuously, non-invasively monitor biomarkers which can usually only be tracked using specialised medical equipment, such as blood glucose and hydration levels. Although, the patent never reveals any particular Apple device nor it's possible use in Apple Watch for a medical application such as blood glucose.

Apple would launch this feature with FDA (Food and Drug Administration) approval after this patent. They might not just introduce this feature like it did with ECG with clinical trials.

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