Fabrication of a high frequency in vivo ultrasonic Doppler wall shear rate measuring device using micromolding techniques

The purpose of this paper is to develop micromolding techniques for the fabrication of a more accurate high frequency pulse ultrasonic Doppler wall shear rate (PUDWSR) device. The PUDWSR device was developed utilizing three, center-aligned, 20-MHz ultrasound crystal-lens combinations with beam angles of 37°, 49° and 58° to the plane of flow with corresponding inter-crystal spacings of 1.51 mm and 2.03 mm. The crystal-lens combinations were made using a micromolding/stamping technique and the correct position of the three crystal-lens combinations was maintained by three fixed-angled wells constructed out of Sylgard using photolithography technology. Both the radius of curvature of the micromolded acoustical lenses and crystal-lens combination angles were found to be within 3% of the design