The present invention provides a small, low power consumption ultrasonic flow velocity meter. The fluid mixing system includes a fluid and a heat engine. An apparatus is described that includes a driver that drives a first current through a line and a termination resistance so that a logical value on the line changes from a first logical value to a second logical value. to form a capacitor structure, or repeat all of the deposition poly-silicon and both of the low resistance and high melting point conductor on the poly-silicon layer more than once. The ring has a plurality of channels adapted to receive retaining features of the implantable medical device to stabilize the medical device within the jar.