Superelastic metal microsprings as fluidic sensors and actuators.

Superelastic metal microsprings fabricated by deterministic rolling of nanomembranes have been anisotropic-strain-engineered via glancing angle deposition. The advantageous applications of metal microsprings in liquid flow rate sensors and chemical-stimulated actuators due to their reliable superelasticity are demonstrated. Theoretical calculation of microspring elongation as a function of flow rate agrees with our experimental observation and reveals that the sensitivity can be well tuned by the geometrical design of the microsprings. Such outstanding mechanical properties of rolled-up metal microsprings should find important applications in future fluidic micro-/nano-devices.