Fig. 5: Pump bots.

A Muscle-driven, impedance-based pump-bot: asymmetric tube deformation (i, ii) generates unidirectional flow (iii) with enhanced output under electrical stimulation (iv)³⁴. Reprinted from (34) with permission from PNAS. B Micro-spherical heart pump: a cardiomyocyte-wrapped PDMS sphere (i-iii) generates pulsatile flow through capillaries, with tracer displacement confirming rhythmic actuation (iv)³⁵. Reprinted from (35) with permission from Royal Society of Chemistry. C Engineered heart ventricle: (i–ii) Aligned cardiomyocytes and layered infiltration on surface and cross-section. (iii) PV loops show contractile response to isoproterenol. (iv) Ventricle mounted in bioreactor for functional testing⁷⁴. Reprinted with permission from Springer Nature. D Valved, cardiac-inspired miniPUMP: (i) integrates a suspension valve for unidirectional flow, (ii) and reproduces ventricular-like mechanics with a pressure–volume loop showing isovolumetric phases (iii)⁷⁵. Reprinted with permission from AAAS.