3

LENS

incredibly thin. You can still use sewable components
designed for conductive thread, just solder your
wires into the holes. Soldering opens the door to
the wider world of electronics, and you’ll be able to
make use of components not specifically designed for
wearable applications.
Even if you already know how to solder, there
are a few things to keep in mind when soldering for
wearables. Soldered joints aren’t flexible, and will
break if flexed repeatedly during wear. A dab of hot
glue can reinforce a soldered connection and make
it last longer. Fabrics stretch, but wires don’t – make
sure there is enough length in your wires to allow for
movement. And while your wires may be insulated,
you’ll still need to keep soldered connections and
components away from moisture and skin. Coat them
with a clear acrylic spray or clear nail polish when your
build is complete.

BATTERIES
Choosing a battery for your project is a balance
between size and power. For wearables, you’ll want
the smallest battery you can get away with, given
the power requirements of your project. To estimate
your power needs, check the datasheets for each
component in your circuit. Find the maximum current
draw for each, and add them together. It’s better to
provide more amps than not enough, so choose a
battery that meets or exceeds this total. If you’re just
starting out, stick with the batteries recommended in
tutorials and example projects. As you build more and
become familiar with components, you’ll get a better
sense of what batteries to choose.

COIN CELL BATTERIES
These are your tiniest option for battery power. Coin
cells are great for low-power projects like powering
a few LEDs, and maybe even a tiny microcontroller.
Battery holders often come with a built-in on/off
switch, and come in sewable form. Coin cell batteries
are low capacity and don’t last long, but they’re small
enough to carry a spare set.

ALKALINE AND NI-MH
RECHARGEABLE BATTERIES
Like coin cells, these are easy to find and you
already know how to use them. But unlike coin cells,
rechargeable versions are available, which is great
for the environment and your wallet. Three or four
AAs should work for most wearable microcontroller
projects. On the down side, AA and AAA batteries are
heavy in multiples, and hiding a bulky battery pack is
tricky in a small project.

LIPO BATTERIES

Because they are small, rechargeable, and powerful

enough to drive complex wearable projects, LiPo

batteries are the battery of choice for many wearables.

However, they are also more delicate than other types

of batteries and require careful handling for safe use.

Never puncture, compress, or expose them to heat.

Don’t place them directly against skin, and don’t store

them in your project. If your project is made of fabric,

remove the LiPo battery before recharging it.

USB POWER BANKS

For projects that need a hell of a lot of juice, a USB

power bank is a great choice. They are high-capacity,

safer, and more durable than LiPo batteries, and most

come with some kind of on/off switch. Often, the

power bank’s specifications are printed right on the

case, check them against the power needs of your

project. USB power banks come in many shapes and

sizes, but tend to be heavy.

Above

Wearables projects

don’t have to start

with specialised kit

Below

Conductive thread

blends invisibly with

fabric but is difficult

to work into complex

circuits

WEARABLE TECH