How is Stress measured by a Fitness watch?
Hey friends, Happy Wednesday!
I aim to write my newsletter issues in a way one can follow them while traveling on a bus, having a coffee, waiting for your food, etc. Let’s jump in!
Thank you for Season 1
I have been overwhelmed by your response to each and every weekly issue of mine for the last couple of months including the December holidays. It means a lot to me, especially your messages suggesting gadgets that I could write about. I know I didn’t make a few of them this season as they didn’t fit quite well with the theme of Wellness Gadgets. But I’ll make sure to write about them in an appropriate season and give a shoutout! 🙂
🚀 Vote on a theme for Season 2
I chose a theme for Season 1 on my own. I randomly came up with this idea for Wellness gadgets, I don’t remember how and why. But for Season 2, the ball is in your court!
I’ll pick gadgets with your help under the theme of your choice for Season 2!! It’ll have another 13 episodes like Season 1.
So take 10 seconds of your time to Vote on the theme for Season 2 by picking an option for the 1 question 😀
VOTE on the Theme for Season-2
📔 Summarizing Season 1
While we’re moving to Season 2, it’s always a good idea to recap what we’ve gone through so far. So just thought I’ll summarize the tech we’ve discussed in Season 1.
We extensively got to cover how a lot of the features work in a Fitness Watch like the step counter algorithm, detecting a heartbeat, pulse rate monitoring, measuring hydration level, computing blood oxygen level, tracking stress, and fall detection algorithm. I’m planning to summarize them and make an Ebook out of it. Will share it with you all next week.
Also, beard trimmers, bladeless fans, pacemakers, self-cleaning water bottles, and smart posture trainer devices were other gadgets that we got to inspect in this 13-episode Season 1 blog post series of Wellness gadgets. While, some of the gadgets like hearing aids, and dehumidifiers were discussed exclusively in my newsletter and I didn’t make a blog post out of it.
All my past newsletter issues and blog posts can be found in my website chendurs.com
✍🏽 Blog posts
My last blog post for Season 1: Wellness gadgets - S1E13 on Measuring EDA response for tracking Stress in a Fitness watch is out!
I have included the content in this week’s issue right below. But if you’d like to read it as a blog post, you can find the same on my website as well.
🧘🏽 How is Stress measured and tracked by a Fitness Watch?
We have sweat glands that are found throughout our skin and they produce sweat when we are stressed, excited, or when we exercise a lot. The more stressed we are, the more sweat is produced by our glands as we do not consciously control sweat. It’s basically an auto-response originating from our sympathetic nervous system. Even if we can’t see with our naked eyes, it happens at a micro level.
And we know that every object can naturally be characterized by electrical resistance and conductance, including human skin. As sweat is comprised of salt water which can conduct electrical signals, therefore the more sweat produced, the greater the flow of electricity. This means that skin conductance is high when we are stressed out. Fitbit aims to measure this response noninvasively aka EDA (Electrodermal activity) as a means to classify our level of stress. It tracks the changes in the electrical conductance of the skin. Note that, exercise can also cause a lot of sweat. So tracking your stress level when you’re not excited or exercising is suggested for getting a close-to-accurate response. Now, let’s look at the hardware design.
Hardware Setup
Electrode: An electric conductor that carries current into the non-metallic part of a circuit like some liquids, gases, etc.
The rim around the display of the fitness watch is partitioned into different sections. The shiny rounded rectangle on the side of the watch shown here is an electrode on one side of the watch. Similarly, it has an electrode on the other side as well. Note that the location and the design of the electrodes could change from model to model. And the rest of the housing on the sides is made out of non-conductive material like plastic, etc.
Figure 1: Fitbit with electrodes on the sides
Method of Usage
Fitbit has an EDA Scan App that is used to measure electrodermal activity. So here is how it’s used. You could place your thumb and index finger on the left and right side of the watch respectively, where the electrodes are positioned, and wait for a few minutes. During this time, it measures the conductance of your skin and the pulse rate change. Finally, it asks you to classify your mood into stressed, neutral, etc. It considers that to provide data on how stressed you are.
Working Principle
As the electrodes are electrically isolated, you close a circuit when your fingers are on the electrodes. Then, a small fixed current is injected across the electrodes which flows through the skin. Now, the voltage across the electrodes can be measured. Thus with the voltage and current values available, we can compute your skin conductance using Ohm’s Law and the fact that Conductance = 1/Resistance.
Conclusion
The skin conductance value measured and mapped to stress level over a month every day can show you how the stress level has changed over time. The App also recommends you perform breathing exercises, meditation, etc., to reduce stress. And this is how Fitbit detects and tracks your stress levels.
❓ Question of the week
What was your favorite topic from Season 1 that you liked the most? Share your thoughts by replying to this email, would love to hear from you. And I’ll share my personal favorite with you.
📱 Gadget of the week
Recycling: Often, recycling is done by hand which makes it a time-consuming process. But AMP Robotics developed a sorting system that uses Artificial Intelligence to identify different types of materials. The system can process high volumes of material, picking them off a conveyor belt with 99 percent accuracy.
✌🏽 Launching Season 2
Thank you all for your support for my Season 1: Wellness gadgets & it means a lot. I’ll share the voting results for the theme of Season 2 and announce it next week. See you in a new Season next week on One gadget at a Time. Thank you for reading.
Have a nice rest of the week, and take care!
Until next Wednesday,
Chendur
