High-Efficiency Atmospheric Water Harvesting enabled by Ultrasonic Extraction

The article “High-efficiency atmospheric water harvesting enabled by ultrasonic extraction” (Nature Communications, 2025) presents a groundbreaking method for extracting water from air without relying on heat-based desorption. The research introduces a vibrational mechanical actuation technique using piezoelectric ultrasonic transducers to extract water from moisture-harvesting materials such as hydrogels. This method achieves an energy efficiency up to 45 times higher than conventional thermal evaporation techniques, surpassing the thermodynamic limit of water vaporization. By converting electrical energy into ultrasonic mechanical oscillations, the process enables the direct release of liquid water droplets from sorbents at ambient conditions, making atmospheric water harvesting (AWH) both more energy-efficient and scalable. The study demonstrates energy consumptions as low as 0.535 MJ/kg, achieving efficiencies exceeding 400% relative to the thermal evaporation limit, opening the path for economically viable decentralized water production systems.

The SmarAct PICOSCALE Vibrometer played a crucial role in characterizing the ultrasonic actuators developed in this study. Specifically:

• The PICOSCALE laser vibrometer was used to measure the vibrational displacement and velocity fields of the piezoelectric membrane actuators under sinusoidal excitation (1 Vpp).

• As shown in Figure 3 (pages 4–5 of the paper), the PICOSCALE was employed to map the modal deflection profiles of the PZ-C actuator membrane at its dominant resonance frequencies (89 kHz, 110 kHz, and 115 kHz).

• These high-resolution interferometric measurements provided nanometer-precision data essential for validating finite element simulations (COMSOL Multiphysics) of the actuator dynamics.

• The device’s sub-picometer resolution and MHz-range bandwidth allowed the researchers to quantify the amplitude and phase of membrane oscillations, thereby optimizing actuator geometry and confirming coupling efficiency between electrical input and mechanical output.

The PICOSCALE Vibrometer thus enabled quantitative modal analysis of the ultrasonic actuators, ensuring precise control over the mechanical excitation used for moisture extraction. Its interferometric accuracy was pivotal in correlating actuator performance with water extraction efficiency, establishing a clear link between vibration amplitude, frequency response, and desorption rate.

Conclusion

The SmarAct PICOSCALE Vibrometer was instrumental in this work by providing high-precision vibration mapping that verified and optimized the mechanical actuation mechanism at the heart of the new, highly efficient atmospheric water harvesting technology.

Acknoledgment

We thank Ikra Ifthekar Shuvo and his team at the Massachusetts Institute of Technology for their valuable cooperation.

Download Link

High-efficiency atmospheric water harvesting enabled by ultrasonic extraction | Nature Communications