US Patent 7288102 Lancing device with decoupled lancet

A lancing device having a low-mass, high-velocity lancet decoupled from a drive mechanism when piercing a user's skin. The drive mechanism includes a spring-driven piston that impacts the lancet on firing to propel the lancet from a retracted position towards an extended position. After impact, but before the lancet reaches the extended position, a stop limits the travel of the piston to separate the piston from the lancet. Precise guidance of the lancet minimizes lateral movement of the lancet.