Design of valveless piezoelectric micropumps using adjoint level-set optimization

Abstract Valveless piezoelectric micropumps offer a compact, modular, and highly efficient solution for lab-on-a-chip applications, particularly where extended lifetime and low power consumption are critical. This work focuses on the performance optimization of valveless piezoelectric micropumps. Specifically, an adjoint level-set optimization framework is employed using an axisymmetric formulation to obtain a design of the inlet and outlet restrictors that achieves a positive net flow rate during micropump actuation under realistic operating conditions. This formulation enables geometries with well-defined fluid–solid boundaries, while reducing the computational cost relative to fully three-dimensional optimization schemes. The optimized design is then integrated into a coupled multiphysics piezoelectric micropump model to comprehensively evaluate the influence of key actuation parameters, including peak-to-peak voltage and frequency. The results demonstrate that high flow rates do not necessarily correlate with optimal efficiency when the power consumption of the piezoelectric actuator is evaluated. Based on this observation, a power-aware definition of valveless piezoelectric micropump efficiency is proposed, capturing the combined influence of actuator geometry and operating conditions. The maximum efficiency of the optimized design is achieved at a peak-to-peak voltage of 20 V and a frequency of 300 Hz, yielding a flow rate of 0.424 mL/min and an energy efficiency of 85.7 (mL/min)/mW. This operating point yields an efficiency that is markedly higher—by more than one order of magnitude—than those reported in the literature for other valveless piezoelectric micropumps when evaluated on a power-consumption basis.