@inproceedings { takahata_wireles, title = {A wireless microsensor for monitoring flow and pressure in a blood vessel utilizing a dual-inductor antenna stent and two pressure sensors}, journal = {17th IEEE International Conference on Micro Electro Mechanical Systems. Maastricht MEMS 2004 Technical Digest (IEEE Cat. No.04CH37517)}, year = {2004}, pages = {216-19}, publisher = {IEEE}, organization = {IEEE}, type = {inproceedings}, address = {Maastricht, Netherlands}, abstract = {This paper reports a micromachined antenna stent (stentenna) that is integrated with implantable microsensors for wireless sensing of blood flow and pressure with no battery. A device that has 20-mm length and 3.5-mm diameter (after expansion) is fabricated from 50 ?m thick stainless steel foil by using batch-compatible micro-electro-discharge machining. This is coupled to two micromachined capacitive pressure sensors of approximately 1.4?1.8?0.5 mm3 dimensions. A 0.5-?m 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 50-60 nH 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 5-40 MHz over flow-rate change of 150-300 mL/min. Pressure sensitivity is 273 ppm/Torr, which is >100? higher than past results}, keywords = {blood vessels,capacitive sensors,haemodynamics,microfluidics,micromachining,microsensors,pressure sensors,silicones}, URL = {http://dx.doi.org/10.1109/MEMS.2004.1290561}, author = { Takahata, K. and DeHennis, A. and Wise, K.D. and Gianchandani, Y.B.} }