Word of the day: bioimpedance. This is the term applied to the measuring of body composition, and it’s very much the headline feature of the Aura Band (from $99), a fitness tracker currently smashing its funding target over on Kickstarter. Giving the band a few taps creates a low-voltage electrical signal that can apparently take readings of your fat, muscle mass, minerals and body water. If - and it’s a big if - it works as advertised, the Aura Band could be a massive hit with fitness types who demand real-time feedback on their progress. And that progress will be rewarded. Every step, workout and activity returns Aura Coins, which you’ll eventually be able to exchange for real-life prizes. No word yet on who the partners will be, but we like the sound of saving up for a new pair of trainers just by opting for the long stomp home from work.