Various things we wrote


Prototyping Fun with a Posture Alarm

We spend a lot of time in front of our computers and we are all concerned about the health of our backs. That has resulted in our stand up work stations, our walking work station and now this fun Posture Alarm Prototype that I'd like to tell you about.

A month or so ago, Gary shared a link with me for a wearable device called the Lumolift that is intended to help with good posture. The feature that interested me the most is that it vibrates when slouching as a reminder to sit up. Currently you can pre-order one for $79. It comes with a handy app that measures the number of steps you take, burned calories, and how much time you are exercising good posture. I started wondering what could achieve the same result without the expense and the 'sometime in the summer of 2014' projected shipping schedule.

I imagined a device with two basic aspects...

  • Some type of sensor to determine when the user is slouching.
  • Some type of notification to get the users attention when slouching is detected by the sensor.

Instead of something wearable, which is not a requirement of mine, I decided to go with something fixed at my work station. So instead of tilt sensors and gyroscopes I started thinking about sensing distance between the computer screen and my upper body.


In Kimmo and Tero Karvinen’s O’Reilly Media book, ‘Arduino Bots and Gadgets’, they provide instructions on building an embedded system called the Stalker Guard. An ultrasonic sensor determines if another object is within a specified distance and activates a vibration motor like the ones you would find in your phone or video game controller. This distance measuring seemed like a good fit for this project. I attached an ultrasonic sensor to a cheap department store pants hanger, which could then be attached to the top of a laptop or some other fixed area around my workstation. The doublebarrel sensors look like eyes and help make it look cute.


Next, I needed to determine what happens when the user slouches. If I’m not going to wear it then I probably don’t need the slouch alarm to be a vibration. I could use LEDs but too many things around my office already light up and blink. I decided to go with sound and in this case I used a small piezo buzzer to create a tone.

The buzzer, battery, microcontroller and on/off switch fit nicely in this trendy Altoids enclosure.


I measured the distance from the sensor to my face, which happens to be ~50 centimeters. If the sensor detects an object <50 centimeters it activates the buzzer at a specific tone. Just for fun, I added a unique tone at 46cm, 42cm, 38cm, 34cm and soforth. This resulted in a fun theramin-esque musical device. Here is a 12 second video...

I've been testdriving it for about a week and so far it works. The buzzer sound has me snapping to attention and when I get bored I can play music like a digital wizard. Perhaps one day scientist will grow us all new and curiously strong backs in giant petri dishs but until then, I've got this handy and smart looking posture alarm.

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