What Tracking Metric Do You Care About?

The most common tracker for collecting data on a body’s movement is designed to count our steps. This technology was first seen with a pedometer and continues to be the source of data given to consumers. Besides a major switch in form factor (from a belt clip to a wristable) most tracking devices need a bit of an extension in order to include other valuable metrics. There are tons of sensors on the market, and they are only expected to grow. Engineers are now beginning to use sensors to detect and measure heart rate, sweat, temperature,   sleep, productivity, calories, GPS coordinates, blood pressure, UV exposure, and glucose levels. So what does these sensors do and what products use them? Keep reading to find out.

Heart rate

There is a simple type of hardware called a PPG that can measure blood beats under the skin. The way it works is a light sensor is placed next to a green light. When your blood pulses under your skin it changes the brightness of the green light placed next to the light sensor; that change in brightness is a signal of a heartbeat. This hardware is simple, but makes for inaccurate data. If you are a maker and bought an open source heart sensors, then you know what I mean. You can simply swipe your hand in front of the sensor and pretend to be a heartbeat. Even so, ingenious software developers have added a few features to this sensor to gain the most accurate data. This type of hardware is also used in a few smart watches, FitBit, Microsoft band 2, and others. If you ever see a green light on your wearable, don’t be scared, it is just a heart rate sensor.

Heartrate is important to measure because it can reveal a lot about your overall health. If your heart is beating too fast for your age and weight than this could mean that something is not working properly inside. Striving for a healthy life includes more than fitness and diet, it also includes stress-free lifestyle that comes with happy hearts.


Galvanic skin sensors are able to detect the molecules within your sweat. Sweating is how a body cools off and releases toxins. With that said, sweat is a treasure chest for anyone interested in what type of data can be collected from the body. This sensor essentially takes what’s inside of you and makes the unknown available on the outside.  For example, if you have been drinking a lot this weekend and find yourself rushing for the train on your way to work in the morning, you will be surprised about the secrets your sweat will reveal about your weekend consumption.

The sensor works by sending a small electrical current through your pores. If you are sweating a lot the signal will return faster than if you are not sweating.


Temperature sensors when combined with heartrate and sweat sensors can reveal a lot about a person, the top example is their emotion. This type of computational data collection is used in Affective Computing, specifically for gaming. The idea is that the computer can know what your emotions are and react appropriately. If you are getting frustrated then your skin can get sticky, your heartrate increases (ever so slightly) and your temperature increases, with all of these data points in mind the computer can ask you to take a moment away and breath some fresh air.


Sleep is another common feature for wearables to track, which also makes it highly diverse in its accuracy within devices. Some products just tell you how long you slept for (but don’t forget to tell it you’re falling asleep), while others know when you have fallen asleep and track your sleep cycles and heart rate. The most productive and enjoyable person is one that is sleeping enough. How much is enough will always be a stem for debate; however most people agree that 8 hours is ideal. I find that I like knowing how well I sleep. Particularly if the sensor is able to tell me when I was in RIM or deep sleep, then I know that I might have been in bed for 8 hours, but I only truly slept for 5 hours.


No longer do fit folks need to count their calories for wearable tech has taken over. Collecting data on the calories burned offers important of information. Particularly if you wish to know what activity is most effective. The hardware behind the calories burned is combined with sensors above. It’s the algorithms that make this data the most important. It’s when you get a new tracker and you see that some count how many calories you have eaten (harder to know without detailed description of the food + weight) while others are how many calories you have burned.


Several sport coaching devices have GPS integrated into the device. This is great for sharing the route traveled as well as the distance. Another great addition to tracking your location is how you see the elevation you traveled. Not all landscapes are flat; therefore including this metric along with the basic activity tracking can improve workout accuracy.

Blood Pressure

Measure blood pressure has taken a while to evolve from its original air squeezing arm-band used in doctors’ offices (a sphygmomanometer and a stethoscope). Yet, for people that suffer from high or low blood pressure, it is great to have a wireless at-home-system.  These devices are not yet a wear-all-the-time wearable, however it does fit nicely into any bag that you take around. Withings has one of the better devices that can connect to your smart phone or tablet where you can share any surprising data with your doctor.


We all know that the sun is getting stronger because the O-zone is getting smaller. This means that every time you visit your dermatologist, you are reminded to put sunscreen on every day on all places of the skin that are exposed. UV detection is an important metric to be reminded of. Some devices measure for your amount of time in the sun and correlate that to the age, and skin sensitivity you have to inform you when it is time to go inside. Others are able to let you know how strong the sun is and send reminders to put more sunscreen on. Either way, you need a smart phone to help translate the data into understandable information.


Insulin measurement is critical for those living with diabetes. There are several devices that have medical approval for reading glucose. Some are chunky watches, while others are small patches the form of choice is left to be decided by the wearer. However it is important of assistive tech to be made for the person using them. It is already a hassle to worry about your health on a day-to-day level, so improving awareness while maintaining a simple lifestyle should be thought about critically.

There are more sensors in the R&D stages that will be smaller and more accurate within the next few years. As we have begun to cross the chasm, it is important for people measure more than steps and calories burned. Having all metrics can also be overwhelming. If you have a question on what device measure a metric best, shoot us an email and we will be happy to share our perspective. You can also join us in person at an event near you!