The Potential Role of Magnetorheological Elastomers as “Smart Materials” in the Future Design of the Artificial Heart and Circulatory Support

Objectives: VAD/ECMO/ECLS became a routine treatment in acute and chronic end-stage cardiac or pulmonary diseases. Despite saving thousands of lives, there are still complications induced by nonphysiological behavior in pump hydraulics. Computational analysis, experimental studies, and clinical observations show constant blood damage manifested by hemolysis, platelet activation, thrombosis, and complement reactions. Pulsatile pumps produce shear stress reaching 300 kPa, axial pumps demonstrate enormous turbulence due to rotation speed exceeding far 5,000 rpm, and centrifugal devices generate a force in hundreds of gravity units. Dielectric or magnetorheological elastomers are known as “smart materials” and are used to develop artificial muscles. Being able to change a length to > 800% under electrical or mechanical force they have a considerable capability to provide improved hemodynamics. In comparison to dielectric elastomeric actuators, magnetorheological elastomers are energy efficient and respond rapidly to variation in force, area, and direction of electromagnetic energy by changing their shape and size. The purpose of our research was to construct and test electromagnetic elastomer as a pump using nontoxic polyurethane and silicone polymers in vitro.

Methods: Two-component elastic polyurethane (Shore A 50, tensile elongation to 560%) and silicone (Shore A 22 and 33 with tensile elongation 1,000 and 370%, respectively) polymers were used to build a magnetic elastomer. Ferromagnetic particles sized < 400 μm were incorporated into elastomer structure. The electromagnetic force with different polarity, direction, and power varying from 5 to 250 N has been applied to produce necessary shape and size deformation of the tube- and bowl-shaped structures.

Results: Both polyurethane and silicon ferromagnetic elastomers showed excellent response to the electromagnetic field, thus providing gentle hydraulics in a self-modified loop in vitro. Using a combination of different sorts of elastic polymers, selective placement of magnetorheological particles with applying programmed force and direction of the electromagnetic field could provide excellent control of the blood rheology during pumping.

Conclusion: Thus, elastomeric actuators represent considerable potential for projecting future designs of artificial heart or other circulatory devices. Nevertheless, diverse interdisciplinary studies have to be conducted to create a “physiology-friendly” machine to replace widely employed models of VAD, CPB, and ECMO in the future.