Table of Content:
- Wearables + Tangible Interaction
- To Microcontroller, or to not Microcontroller (Analog Circuits)
- Soft Enclosures
- Body Placement
Wearables have become increasingly more popular in the last few years with products like FitBit, which has the functionality to tell you how many steps you take and calories burned throughout the day. Many wearables are used to improve daily habits in our lives by tracking how much we do certain things and then revealing how we can better ourselves. Even though this is a large part of the wearables market, and even the appeal to wearables, it is not the only purpose. Wearables can function as a medium for self-expression and even to control games.
In this report I will attempt to analyze common sensors and microcontrollers used to build wearables for various tangible interactions. This is meant to be the start of guide to enable people to explore the possibilities of wearables through simple DIY prototyping.
Wearables + Tangible Interaction
Why is it worth considering wearables when designing tangible interfaces? The first thing to consider when making a wearable is why you are making something that is to be worn. The goal of a wearable is to make something a person can wear to achieve something in an intuitive way. The most important aspect of a wearable is that it’s worn as a part of the body. This can free a user from some restrictions a traditional tangible interface has–for example, in the game Hit Me! by Kaho Abe, players wear the interfaces on their heads. The goal of the game is try to press the opponent’s button, which triggers a picture to be taken. The player with most pictures of their opponent wins the game.
What makes wearables challenging is that there are many variables to consider. Wearables is really just a fancy word for Interaction Design, and the only difference is that the body is the main interface you are designing for. The body is not an easy interface to work with: it sweats, it moves in ways you can’t always predict, and it comes it different sizes. It’s challenging enough building something that doesn’t break, but how do you build something that can be worn and holds hardware. The key to wearables is finding the right balance between soft and hard, which can only really be done through user-testing.
III. To Microcontroller, or to not Microcontroller
Before using a microcontroller in a wearable, consider if you need to. Sometimes using an analog circuit is a better approach to what you are trying to achieve. Not using a microcontroller allows a lot more flexibility in the design. One of the main reasons for this is, NO WIRES. At least, no wires going from your microcontroller to your sensors. One of the great things about wearables is that it’s simple to make soft circuits, or even make soft sensors like FSRs, soft buttons, or stretch sensors. This nice thing about not using a microcontroller is that it makes the overall product lighter and body placement also becomes less of an issue.
How to make a soft analog circuit (example)
Foam, or a thicker material
Main fabric (felt, muslin, jersey)
3V coin cell battery
Electric tape or hot glue
Sensor (vibration motor)
First cut shapes of the conductive fabric, main fabric, and foam. The main fabric should be slightly larger than the conductive. Cut a few holes in the center of the foam. This is what you will place in between the main fabric and conductive. Strip the ends of the wires of the power and ground legs of the vibration motor carefully. Take each leg and weave it into the a piece of conductive fabric. You should have a piece of conductive fabric on each leg. Place the coin cell between the layers of fabric on the negative side. Test out that when you press down that the positive conductive piece makes contact with the battery. Test this out a few times and when you’re ready sew it all together.
LightBlue Bean: lightweight, bluetooth, loads Arduino sketches. Most difficult part is setting up.
ATTiny85: great to prototype with photo sensors, LEDs, and servo motors.
Flora + Flora BLE Module
Arduino 101: easy to program, bluetooth capability
BlueFruit LE Micro
There are many ways of making soft switches. Some people do this with velostat or with conductive fabric. With anything soft, it requires a few different types of fabric: conductive, main fabric, and foam. The conductive is what completes the circuit, the main houses the switch, and the foam is used for resistance. The trick is making the foam thick enough so it’s not triggered continuously, but providing enough space for any user to be able to trigger the button easily. Below is an example of how to use soft switches with game controller.
FSR (Force Sensing Resistor)
These are seen often in wearable projects, as they are can be used in game controllers, or wearables that need sensors to be triggered by pressure.
Below is a good example of an FSR in a game controller. This project was done by Zoe Bachman, who made FSRs to be placed in the soles of shoes in order to control a game. She used the Arduino MKR 1000, which has Wi-Fi capability.
Accelerometers are a great way to send data in a wearable.
In this example made by KC Lathrop, the glove has an accelerometer sending data via a serial port to the screen which is mapping the values and simulating the speed of which the player is flying. This was done by using a LightBlueBean.
Another example, Moving Messages, the users wear arm bands that each have an accelerometer. The data they send change the messages coming on the screen.
Servo motors can have a lot of difficult functionality in a wearable. They are used for many reasons, for example, to show movement, or even to create space. Here are two examples of uses of servo motors in wearables:
1 . Volume, a wearable by Anne Goodfriend, encourages plus-size women to take up more space. This is an example of a self-expression wearable and how to properly design soft things with many hard components. The input is a microphone sensor and the output is servo motor. The motors are triggered by the volume coming in from the microphone. In order order to simulate that the garment was growing she built a mechanism, much like a paper pop-up book. For more info: http://annekgoodfriend.com/#portfolio-2
2. Ha-mazan, a wearable done by Renata Gaui, is an elbow patch that helps cyclists communicate to other vehicles. In this prototype, Gaui made two circuits, one with the input as a toggle switch with an output of a servo motor and the second with the input as a photocell with fiber optic LEDs as the output. This a great demonstration how you don’t need to have the final input in order to experiment with an output, like a servo motor. In the next version Gaui plans to trigger the servo motor with a pressure sensor on the bike’s handle bar to signal when they are making a turn. For more info: http://www.gauirenata.com/category/spring-2016/wearables/
A soft enclosure is the same concept as a hard enclosure, except that it’s soft. Why are soft enclosures tricky? As discussed in previous sections, most components are hard, and sometimes heavy, especially when using a microcontroller. Not only do you need the enclosure to be soft to hide the components, you need it to be accessible, and also unobtrusive.
Below is the same glove with different views of the soft enclosure. In the picture on the left, you can see there is a little house for the microcontroller that enables you to easily slide it out if you need to change the battery or fix another issue. In the picture of the right shows the underside of the glove, that has another layer of fabric and enclosed with velcro. (velcro is a great friend in soft enclosures).
You will learn quickly when making wearables that there are ideal places to design your wearable around. None of this is rocket science, it’s more just thinking about how someone would move in your product, which goes back to the difficulty of designing for the body. How do you make something that won’t break when people wear it, and it’s not good design if you have to tell someone how to use it.
What to consider:
How much of that part of the body is stable?
How far do the wires need to reach?
How much weight does the circuit carry?
-wrist, forearm, elbow
-under the foot
“A Wearable Haptic Game Controller”