AFAIK, all the major manufacturers (Specialized, Trek, Giant ...) have torque sensors on their mid-drives. Many (all) have a cadence system too and use the torque, cadence and bike speed to determine the amount of assist also factoring in the level the assist is set at. Lots of individuals opine that torque sensors are superior to cadence, but I've ridden many bikes with torque sensors and own a Yamaha-equipped Haibike, and IMO the cadence-only system on my BBS02 hardtail is as good as the others.