Energy harvesting’s popularity does seem to have waned in the past few years, but that hasn’t stopped Israeli startup Wiliot securing a $30mn Series B round to fund its RF-harvesting Bluetooth system, which can provide a battery-free way of powering a small senor device – kitted out with temperature and weight sensing, as well as authentication. As far as we can tell, it’s more an improvement on older designs than a radical reinvention of the wheel. At the heart of the design is a tiny ARM MCU, which can be connected to sensors where needed. The most important part is the antenna circuitry that lets the system generate electricity from the ambient radio waves that surround it – chiefly WiFi,…