HETEROGENEOUS NANOSTRUCTURES FOR BIOMEDICAL DIAGNOSTICS - Bio-Inspired and Nanoscale Integrated Computing - page 444

Figure 16.15. Packaging of the polymer shear stress sensor.

hours) to carry the electric signals from the arterial circulation to the external
circuitry. After that the sensor was mounted to the catheter with biocompatible
epoxy leaving the sensing elements facing the blood flow. This step will take one
day for the epoxy to cure and complete the packaging process. The diameter of the
packaged sensor is around 400 m m.

16.4.3.3. In vivo Assessment of Intravascular Shear Stress. Real time
ISS measurements were acquired from the NZW rabbit's aorta, specifically the
abdominal and aortic arch. Deployment of the polymer device into the rabbit's
aorta was performed in compliance with the Institutional Animal Care. A pilot
study has been conducted by deploying the MEMS sensors into the aortas of New
Zealand White (NZW) rabbits (Fig. 16.16a). A 23-gauge hypodermic needle and a
26-gauge guide wire were introduced into the left femoral artery via a cut-down. A
rabbit catheter (0.023 OD) was passed through the left femoral artery.

The diameter of the sensor with guide wire was 400 m m and that of the aorta was
2.4mm.The animal was heparinized (100U/kg) intra-arterially. Under the fluoro-
scopic guidance (Phillips BV-22HQ C-arm), the catheter integrated with the MEMS
intravascular device was deployed in the abdominal aorta for real-time intravas-
cular shear stress measurements (Fig. 16.16b). The position of the catheter was
visualized by fluoroscopy. The catheter was steered to a position (orientation) that
the sensors were able to detect the maximal voltage output. Shown in Figure 16.16b
is the real-time voltage signal output in response to

uu ID 0.038 u

B 200 beats/min. The periodic

changes reflected the respiratory variations at 30 breaths/min. Calibration and

validation were performed to assess the non-Newtonian properties of blood flow.

B

16.4.4. MEMS Liquid Chromatography (LC)
In parallel to MEMS shear stress sensors and nanowire-based FET, the develop-
ment of MEMS liquid chromatography (LC) provides a new venue to detect