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Blockage of pipelines due to accretion of salt particles is detrimental in desalination and water-harvesting industries as they compromise productivity, while increasing maintenance costs. We present a micro-/nanoscale approach to study fundamentals of scale formation, deposition, and adhesion to engineered surfaces with a wide range of surface energies fabricated using the initiated chemical vapor deposition method. Silicon wafers and steel substrates are coated with poly(1H,1H,2H,2H-perfluorodecylacrylate) or pPFDA, poly(tetravinyl-tetramethylcyclotetrasilohexane) or pV4D4, poly(divinylbenzene) or pDVB, poly(1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasilohexane) or pV3D3, and cross-linked copolymers of poly(2-hydroxyethylmethacrylate) and poly(ethylene glycol) diacrylate or p(PHEMA-co-EGDA). Particles of salt (CaSO 4 •2H 2 O) are formed and shaped with a focused ion beam and adhered to a tipless cantilever beam using a micromanipulator setup to study their adhesion strength with a molecular force probe (MFP). Adhesion forces were measured on the substrates in wet and dry conditions to evaluate the effects of interfacial fluid layers and capillary bridges on net adhesion strength. The adhesion between salt particles and the pPFDA coatings decreased by 5.1 ± 1.15 nN in wet states, indicating the influence of capillary bridging between the particle and the liquid layer. In addition, scale nucleation and growth on various surfaces is examined using a quartz crystal microbalance (QCM), where supersaturated solution of CaSO 4 •2H 2 O is passed over bare and polymer-coated quartz substrates while mass gain is measured in real time. The salt accretion decreased by 2 folds on pPFDA-coated substrates when compared to that on p(HEMA-co-EGDA) coatings. Both MFP and QCM studies are essential in studying the impact of surface energy and roughness on the extent of scale formation and adhesion strength. This study can pave way for the design of scale-resistant surfaces with potential applications in water treatment, energy harvesting, and purification industries.

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Transcranial focused ultrasound provides noninvasive and reversible approaches for precise and personalized manipulations of brain circuits, with the potential to transform our understanding of brain function and treatments of brain dysfunction. However, the effectiveness and safety of these approaches have been limited by the human head, which attenuates and distorts ultrasound strongly and unpredictably. To address this lingering barrier, we have developed a Relative Through-Transmit (RTT) approach that directly measures and compensates for the attenuation and distortion of a given skull and scalp. We have implemented RTT in hardware and demonstrated that it accurately restores the operator's intended intensities inside ex-vivo human skulls. Moreover, this functionality enabled effective and intensity-dependent transcranial modulation of nerves and effective release of defined doses of propofol inside the skull. RTT was essential for these new applications of transcranial ultrasound; when not applied, there were no significant differences from sham conditions. Moreover, RTT was safely applied in humans and accounted for all intervening obstacles including hair and ultrasound coupling. This method and hardware unlock the potential of ultrasound-based approaches to provide effective, safe, and reproducible precision therapies of the brain.

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