Patent hints future Apple Watch may come with non-invasive blood-sugar reader

Apple Watches are the most advanced smart wearable, especially in the past four years, each iteration has been upgraded with critical health monitoring sensors to track irregular heart rhythm, Electrocardiogram (ECG), Atrial Fibrillation (AFib), SpO2 (blood-oxygen-level), VO2 Max and have saved thousands of lives around the world.

Now, Apple plans to take the Watch to the next level with the new patent, which may one day be able to detect blood sugar level without any need for intrusive methods of drawing blood; instead, use a particular electromagnetic wave in a terahertz (THz) frequency band that can help sensors in the Watch to compute the biometric data as close to a medical device.

In the latest patent approved by United States Trademark and Patent Office (USTPO) to Apple, the Cupertino-based company is close to getting the aforementioned sensor in to a consumer electronics device, presumably the Apple Watch soon.

Instead of using light, Apple intends to utilise electromagnetic waves in the terahertz (THz) frequency band that can be used to identify minute contents gas, liquid or solid in the blood on the wrist to make a near-accurate blood-sugar reading.

"One or more processors of the electronic device determine a spectral response of a received signal indicative of the reflected EM wave. The spectral response includes absorption spectra at a frequency in the THz frequency band that is indicative of the transmission medium in the environment (read blood). The one or more processors compare the absorption spectra with known absorption spectra of target transmission mediums. Based on results of the comparing, the one or more processors identify a particular target transmission medium as being the transmission medium in the environment, and determine a concentration level of the identified target transmission medium in the environment," reads Apple patent.

However, there is some engineering issue of fitting a lot of sensors into a compact device such as the Apple Watch and also the company has to deal with battery draining. It needs a lot of power to measure all the bio-metrics to compute blood-sugar level.

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"Today's sensor technologies (e.g., metal-oxide (MOX) gas sensors, electrochemical gas sensors) can detect a few gases but have several disadvantages. For example, integrating a gas sensor on an electronic device requires an aperture or opening to allow air to flow onto the gas sensor so that the gas can be detected. The design of an aperture into a consumer electronic device poses several challenges. The aperture may degrade the water resistivity of the device. Also, the size of the aperture may be constrained due to a tradeoff between the form factor and gas detection capability. In addition to aperture constraints, the number of gases detected by a given sensor is limited and one sensor cannot detect gas, liquid, and solid materials. Integrating multiple sensors on the consumer electronic device to detect gas, liquid, and solid materials would increase the size and cost of the consumer electronic device. Also, many of today's gas sensors have a high idle-time current consumption to maintain the properties of the sensor. For example, MOX gas sensors have heating elements that are used to maintain a certain temperature of the sensor at all times. Also, the accuracy of today's gas sensors drifts over time requiring periodic calibration," reads the Apple patent's background description.

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Going by the complications involved in fitting multiple sensors into an Apple Watch, we can't expect to see a commercial model make its debut in the market anytime soon.

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