Page 570 - Handbook of Biomechatronics

Artificial Hearts 563

Fig. 36 Schematic showing wireless transcutaneous energy and control transfer across
the skin.

New nonradiative resonant magnetic coupling has allowed high-
efficiency alignment tolerant wireless energy transfer over greater distances
than was previously available. These devices use near-field strong coupling
modes that arise between two high-efficiency resonances tuned to slightly
different frequencies. This technology also makes use of high permeability
materials in the resonators that concentrate the transmitted magnetic flux.
The latest systems can be separated by distances comparable to their diam-
eters (Kyo, 2014).
Robust new battery technologies specifically tailored for implantable
electronics provide higher power densities and therefore longer run times
without external power as well as lifetimes of up to 3 years before replace-
ment is required.

6 OTHER CONSIDERATIONS

Modern pump design relies heavily on computational fluid dynamic
(CFD) analysis to ensure that fluid shear is minimized and stagnation points
are avoided, as excessive shear results in increased hemolysis and stagnation
results in clotting. Additional techniques to identify problems include visual
observations using scaled up transparent pump models that maintain the
Reynolds similarity law to examine flow. These models use particle tracking
velocimetry techniques with very fine spatial resolutions to track particle
movements close to the pump walls.
A final consideration is the selection of biocompatible materials for pump
lining and pump housing. Some of these have been addressed earlier.