A Wireless Microsensor Utilizing a Micromachined Antenna Stent and Pressure Sensors for Monitoring F

Ken’ichi Takahata
Graduate Student UM

ABSTRACT:
This presentation will introduce a micromachined antenna stent (stentenna) that is integrated with implantable microsensors for wireless sensing of blood flow and pressure with no battery. A stent typically has mesh-like walls in a tubular shape, and once positioned by a catheter, is expanded radially by the inflation of an angioplasty balloon. Its primary task is to physically scaffold blood vessels that have been narrowed by plaque accumulation. A developed device that has 20mm length and 3.5mm diameter (after expansion) is fabricated from 50 µm thick stainless steel foil by using batch-compatible micro-electro-discharge machining. This is coupled to two micromachined capacitive pressure sensors. A 0.5 µm thick parylene layer provides electrical insulation. The integrated device is deployed inside a silicone mock artery with a standard angioplasty balloon. The planar structure is plastically deformed to a tubular shape, resulting in dual helical coils with 50-60nH each. These L-C tanks are used to wirelessly probe pressures at two points along a channel for flow-rate detection. Fluidic experiments that emulate a blockage in the mock artery demonstrate that the resonant impedance and phase provided by the LC-tanks to a separate transmitting coil shift by 5-40MHz over flow-rate change of 150-300mL/min. Pressure sensitivity is 273ppm/Torr, which is >100x higher than past results.

BIO:
Kenichi Takahata received the B.S. degree in physics from Sophia University, Tokyo, Japan, in 1990. He is currently working toward the Ph.D. degree in Electrical Engineering at the University of Michigan, Ann Arbor. In 1990, he joined Matsushita Research Institute Tokyo, Inc. (Panasonic), and was with Matsushita Electric Industrial Co. in Japan until 2001. In Matsushita, he was engaged in microfabrication technologies including micro electro-discharge machining (micro-EDM), which involved various task-forces for such as ink-jet printing head and audio-visual hard disk drive and also a Japanese national project of Micromachine. In 1997, he was appointed Researcher in the International Joint Research Program funded by NEDO of Japan and collaborated at University of Wisconsin-Madison for a new technique based on micro-EDM and deep X-ray lithography (LIGA) processes. From 1999 to 2001, he was a Visiting Scientist at UW-Madison for a joint research on the batch mode micro-EDM technology that utilizes lithographically fabricated electrodes and its application to MEMS. He currently has 20 publications, 5 issued patents, and 19 pending patents in US and Japan. His research interests are in MEMS realized by a combination of silicon and non-silicon based microfabrication technologies.