Most smartwatches and fitness trackers are crammed full of sensors. Take the Apple Watch Series 4 as an example, which has a barometric altimeter to measure altitude, an electrical heart sensor to take ECG readings, an accelerometer to keep tabs on movement, an optical heart sensor to measure your heart rate, a gyroscope to track movement and rotation, and an ambient light sensor to control the brightness of your screen.
You see what we mean.
Although space is extremely limited inside wearables, as the tech becomes smaller and more advanced, new sensors are added to tell us more information not only about ourselves, but the world around us. Apple recently shook things up when it added an electrical heart sensor into the Series 4, with many more tech brands expected to follow suit.
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The big question now is: what other sensors will be added to the next generation of wearables this year, next year and beyond? As you might expect, itās not easy to guess, and many companies are secretive about revealing new tech.
But we can make some predictions about whatās in store for mainstream wearables, based on more niche products currently seeking funding, smaller projects that never made it off the ground, and what the medical tech community is researching and working on right now.
Air quality, pollution and toxic gas
Over the past four years, thereās been a surge in tech dedicated to sensing the quality of the air around us, whether thatās general pollution and allergens or more harmful gases and toxins.
Air sensing and cleaning tech isnāt new and has already made its way into our smart homes with devices like the Netatmo Home Coach. But the air we breathe at home only makes up part of our days.
As youād expect, a number of companies are already coming up with ways to carry air-sensing tech with us 24/7. Plume Labs launched the Flow wearable air pollution tracker in June 2018. It looks like a memory stick and attaches to bags or clothing to track pollution as you travel. The data it collects then helps to build a crowdsourced map of the air quality in your city ā and flags up places to avoid.
The problem with adding air-sensing tech to wearables is that generating a reading relies on a number of different components. For example, Flow works by shooting a laser beam from a particulate matter sensor at air particles that enter the device. The light dispersed from them is translated into an electrical current, which is then read by a VOC and NOC sensor.
There are other ways of measuring air quality, but right now packing that kind of tech inside the small body of a smartwatch presents a challenge.
Thatās not to say tech brands arenāt trying. In January 2019, the team at Patently Apple spotted an Apple patent for the integration of poisonous gas sensors in both the Apple Watch and iPhone. The patent is mainly aimed at carbon monoxide sensing, which is an odourless gas that can be deadly.
Although most Apple patents donāt make their way to a finished product, this one is interesting because in another iteration it could be used as a continuous monitor, like the Flow, but on our wrists. This might be used to help monitor air quality in areas with high pollution levels, but could also be used by certain professions, such as miners who need to be alerted to the presence of poisonous gases.
Blood pressure monitoring
Last year we explored why blood pressure is wearable techās next big challenge, and how a number of companies are already stepping up to help people identify hypertension.
There are already lots of different smart blood pressure monitors that you can use yourself at home, as well as the Omron HeartGuide wearable, which cleverly adds a blood pressure monitor in the cuff of the smartwatch.
Most blood pressure monitors need to cut off circulation to be able to take a reading, which has made building this kind of tech into slim wearables difficult. As well as that, the upper arm is the gold standard for measuring blood pressure, the wrist isnāt so effective.
Microsoft is looking at tracking blood pressure from the head
But there are other ways to measure blood pressure and Samsung recently launched the Galaxy Watch Active, which uses an optical monitor to measure blood pressure instead ā although this tech is yet to receive FDA clearance.
Depending on the success of this type of optical monitor, we might see blood pressure-sensing technology in other devices soon. After all, Fitbit CEO James Park mentioned the development of blood pressure monitoring capabilities as far back as 2015.
And, as youād expect, Apple has filed a patent for an inflatable blood pressure monitor, while Microsoft has also been exploring the possibilities of adding blood pressure monitoring tech into a head-mounted device.
When it comes to unlocking phones, a fingerprint sensor is now commonplace on many major models. But new kinds of sensors that look for different biometric information from our bodies could soon be used to let our wearables identify us ā and ensure we're the only ones using them.
Another patent filed by Apple provides details of a wrist biometric sensor thatās located on the inside of a watch band and can read different patterns of skin texture. The sensor thatās proposed in the patent includes a plurality of biometric sensing pixels, which is coupled with a processor to make sense of the skin texture pattern and use it as a form of authentication.
This isnāt the first time Apple has looked into adding biometric sensors for authentication purposes in its wearables. Back in 2015, another patent was filed that covers an identification system based on Plethysmography, which uses light sensors to record changes in the volume of blood.
Thereās also been similar research into ways to tell if someone is who they say they are based on the veins in their wrist. A 2016 study proposed a wrist vein sensor that would use near-infrared (NIR) lighting to capture detailed wrist vein images, which researchers found were unique across all subjects.
There are all kinds of authentication sensors being used in other kinds of technology, from gait-sensing to iris scanning. But for biometric authentication to be integrated inside a wearable it needs to be small and ideally sense markers that are present on someoneās wrist, which is why both skin texture and wrist vein images could prove to be useful in the future.
Keeping tabs on glucose levels
The ability to monitor glucose levels from our wrists would make a huge difference to personal health tracking and, if it was accurate enough, the lives of those living with diabetes.
There are already plenty of glucose monitors available for personal use, but the benefits of having a non-invasive, continuous glucose sensor in a wearable would mean you could see, in real-time, the impact sugar intake and exercise has on your glucose levels.
The implications for this would be that you could better, and more instantly, tweak your diet. And, considering diet is a huge part of maintaining a healthy lifestyle, it could be a life-changing metric to have on hand.
Most companies that make wearable technology are likely considering whether glucose monitoring is a possibility. Apple was recently granted a patent for technology that sounds similar to non-invasive glucose monitoring and uses a light-based optical sensor to check your blood for glucose.
Fitbit has also made moves into the glucose monitoring space. Firstly, it teamed up with One Drop to bring diabetes management solutions to Fitbit Ionic users. And more recently, it invested $6 million in Sano, a company thatās been developing a small patch that can track your glucose by painlessly reading the interstitial fluid under your skin.
However, one of the biggest challenges of bringing this kind of tech to wearables is that itās difficult to get a good reading through non-invasive methods on our wrists. This means that even if glucose monitoring comes to our wearables, it might not be accurate enough to help advise on insulin dosage for those with diabetes.
Sensors designed to take readings from sweat can monitor all kinds of things, including electrolyte levels to help flag dehydration and fatigue in athletes; blood sugar levels to track diabetes risk; or cortisol levels, which can influence emotional stress, metabolism, blood pressure and more.
There are a number of different sensor technologies that can measure sweat, including using an electrochemical sensor that can be fitted into a headband or wristband, as well as patches that are applied directly to the skin. One patch, currently being developed by researchers at Stanford University, consists of a membrane that allows the salt found in sweat to pass through then collects and measures the cortisol on the way.
Similar sensors have made their way into wearable devices already. The University of Pennsylvania has used graphene to create the SweatSmart by GraphWear, and companies like LVL and Halo Wearables have also been looking at sweat as a measure of hydration.
Although there donāt seem to be any solid plans for adding sweat sensors to any mainstream wearables, itās a good way to keep tabs on health for a number of reasons, including the fact that itās non-invasive, offers continuous monitoring and can flag up many physiological conditions. It could be down to the ambitious startups to make the breakthrough in sweat-sensing first before the major wearable tech companies see the potential.
Many of these sensor technologies could still be a long way off from being added to our wearables, by which point we might have done away with wrist-bound wearables altogether and have moved onto skin sensors or even ingestibles. However, Appleās move into ECG-reading tech last year shows that major wearable companies are dedicated to building new sensors into their devices as soon as the tech allows it, in order to combine data points and build an even more accurate picture of our health.
Something to read next
- How your smartwatch's ECG feature could save your lifeThis emerging technology is already saving lives
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- The holy grail: What you need to know about wearables and glucose monitoringIt's what everyone is shooting for, but is it possible?