Membranes used in water treatment are prone to fouling, leading to flux decline, increased operational costs, and reduced lifespan. Conventional antifouling methods, such as chemical cleaning and backwashing, are effective but have significant drawbacks. This study introduces active polymeric microfiltration membranes with embedded self-cleaning functionality by printing electro-active polymer (EAP) actuators on porous PVDF and PTFE membranes. The design parameters for the membrane-actuators, including membrane material selection, actuator placement, and active layer thickness are investigated. During membrane excitation, resonance frequencies/modes, surface displacements, velocities, and accelerations are detected with laser Doppler vibrometer (PSV-400). By leveraging the electrostrictive properties of the P(VDF–TrFE–CTFE) terpolymer, the actuators generate out-of-plane surface vibrations, achieving average surface accelerations of up to 75 m s−2 (600 V, 4548 Hz) and local surface accelerations up to 255 m s−2 (600 V, 6560 Hz). Particle manipulation in air and aqueous media is respectively tested with randomly distributed metal alloy balls (200 µm diameter) and Iriodin 153 Flash Pearl suspension (1 wt%) on the active membranes. The dry metal alloy balls show strong resonant dislocations near 3500 Hz and 6700 Hz frequencies, while Iriodin 153 Flash Pearl particles (20–100 µm diameter) are visibly mobilized and redistributed at ≈3100 and 5400 Hz frequencies. The results indicate that mechanical agitation of filtration membranes via embedded actuation is a viable method for foulant mobilization, and will be further investigated for fouling mitigation in membrane filtration technologies. ... Read more

A new and sustainable membrane manufacturing method is 3D printing, which reduces the number of fabrication steps, waste production, and the corresponding CO₂emissions. It further enables fabricating membranes with well-defined pore size, shape, and configuration. Here, we study 3D printing of microfiltration membranes using a novel dual-wavelength microstereolithography method. Via the gradient descent method, we are able to calculate and control a printable membrane with micrometer precision, enabling the possibility of printing membranes directly. Hydrophilic porous membranes with cylindrical microscale pores (≈10 μm in diameter) are printed from polyethylene glycol diacrylate (PEGDA). Membrane printing procedure and postprocessing steps are thoroughly investigated to print consistent membranes with uniform thickness. The membranes are fully characterized using SEM, FTIR, contact angle, and surface roughness measurements. The pure water permeability and separation performance of the 3D-printed membrane are further investigated and compared with those of commercial hydrophilic PTFE membranes. The 3D-printed membranes show similar permeability values to those of commercial membranes and could successfully separate oil droplets from oil-in-water emulsions. The membranes’ permeability is further predicted using a 1D tube model and numerical modeling. The effect of material’s property (e.g., swelling) and pore deformation during pressurization are studied to understand the discrepancy between the calculated and the experimental permeability values. The results provide valuable insights into the permeability prediction of 3D-printed membranes and the corresponding design optimization. ... Read more