Smartwatches are great. Or they would be if you didn’t have to remember to charge them almost every other day. Go for something with a six-month battery and you’ll sacrifice features; go for something with lots of features and you’ll have to keep your charger cable handy. Before long your expensive watch gets thrown in a drawer and forgotten about.

The Matrix PowerWatch aims to redress that balance a little, with people-powered technology. That sounds a little more sinister than it is: the watch uses your body heat to charge its battery. The device also claims to measure the calories you burn, your activity and your sleep. It’s water resistant to 50m, and although it doesn’t rival the functions of an Apple Watch it certainly covers the basics. Shipping costs are high, though – an eye-watering $70 on top of the PowerWatch’s $199 price.