At our highest aspiration, the UP system helps you make everyday choices that enable both short and long-term health benefits. Every aspect of our product, from industrial and software design to data analytics, is crafted in service of this. With UP3, we wanted to significantly increase our ability to understand your physiology, and translate those signals into actionable insights. Specifically we wanted to create:
- The most efficient sensor platform, capturing wide range of signals
- A system that adapts to the individual wearer’s physiology
- The smallest form-factor, complementing your personal style in a discreet way
- All this with a battery life of up to 7 days
A key part of realizing our goal was choosing the right sensor technology, and carefully designing how it integrates with the rest of our system in service of you. While there are several off-the-shelf technologies available—including optical sensors—none of them meet our goal of 24/7 wearability with up to 7 days battery life. The Jawbone acquisition of BodyMedia in 2013 gave us access to a wide-ranging IP catalogue for multi-sensor platforms. Armed with a decade of expertise on our own in building on-body sensors, together we created UP3 packed with the following technology:
- A precise accelerometer tracking steps and activity
- Two temperature sensors collecting ambient and skin temperature
- A bioimpedance sensor collecting heart rate, respiration rate and galvanic skin response
Accelerometer and temperature sensors are fairly common these days, found in most activity trackers on the market. Bioimpedance, on the other hand, is a novel sensor we are introducing with UP3.
Bioimpedance – The foundation of UP3
Bioimpedance sensors measure the resistance of bio-tissue to a tiny amount of electric current, capturing a wide range of physiological signals. Traditionally, bioimpedance analysis is used in clinical settings to measure your body composition, such as body fat with respect to your lean body mass. However, with UP3 we have translated this complex technology into a comfortable wrist form factor that you can wear 24/7.
Aside from issues around size and battery life, there are other reasons we decided against optical sensors. There are well-reported issues with skin tone and light interference, but more importantly, optical sensors measure your heart rate by looking at blood flow through your capillaries. While this is a good measure at low heart rates, the blood flow slows as it moves from the arteries through the capillaries below the skin making it imprecise.
The bioimpedance sensor in UP3 can look deeper inside the body, and is tuned to look for signals at specific depths. The sensor measures very tiny impedance changes within your body. For heart rate, we are measuring the impedance changes created by the volume of blood that is flowing in the Ulnar and Radial arteries. Because we are able to see the arterial flow, we believe it can maintain a more accurate tracking of your heart rate at your wrist than traditional sensing systems.
Further, because we can control how deep the sensors penetrate we can extract many other signals beyond heart rate. We will be able to see respiration (largely due to changes in oxygen in blood and surrounding cells) and hydration.
So how does it work?
The visible part of the bioimpedance system is the set of four electrodes embedded into the flexible strap. All four electrodes work in sync to form a tetrapolar (4 pole) system. Two outer electrodes drive tiny electrical energy and the two inner electrodes pick up changes in voltage. Amazingly, the resultant signal (which is imperceptible to the wearer) contains rich data about your physiology.
- Battery Life – Bioimpedance is significantly less power hungry compared to other sensors (Optical, for example)
- Form Factor – Our platform is lot more efficient. With just one sensor we get multiple signals. Unlike other fitness trackers, UP3 is not burdened with many single purpose sensors.
- Rich Physiological Information – The magical aspect of the system is the amount of rich information embedded in the signal. Heart rate is just the beginning. There is more we can unlock as we learn more about you.
- Updatable Technology – Given the versatility of the sensor platform, we are able to (and we will) unlock exciting new features with a simple, free, over-the-air firmware updates in the coming months (the tracking of other signals, for example.
At these early stages, you will see us surfacing simple outputs from bioimpedance, like resting heart rate and advanced sleep tracking. Out of the box we have optimized our system for these two features:
- Advanced sleep tracking – Wake, Light, REM and DEEP stages of sleep (read more about the sleep tracking capabilities of UP3 here).
- Resting heart rate monitoring – Heart rate measured moments after you wake up, before external influences. (read more about the heart rate tracking capabilities of UP3 here).
This is just the beginning
UP3 is a big step toward creating a scalable multi-sensor platform, and our system captures rich physiological data about your bio-state. Measuring resting heart rate is just the beginning. We will unlock exciting new features including “passive” and “on-demand” heart rate, and in time respiration rate, hydration tracking and skin galvanization. And the best news is because UP3 is updatable you can take advantage of these new features and updates without compromising size or battery-life and without having to strap on extra sensors. We can’t wait to introduce the UP community to UP3 – the most advanced wearable we’ve ever created.