Aerosolized pathogens are a leading cause of respiratory infection and transmission. Currently used protective measures pose potential risk of primary/secondary infection and transmission. Here, we report the development of a universal, reusable virus deactivation system by functionalization of the main fibrous filtration unit of surgical mask with sodium chloride salt. The salt coating on the fiber surface dissolves upon exposure to virus aerosols and recrystallizes during drying, destroying the pathogens. When tested with tightly sealed sides, salt-coated filters showed remarkably higher filtration efficiency than conventional mask filtration layer, and 100% survival rate was observed in mice infected with virus penetrated through salt-coated filters. Viruses captured on salt-coated filters exhibited rapid infectivity loss compared to gradual decrease on bare filters. Salt-coated filters proved highly effective in deactivating influenza viruses regardless of subtypes and following storage in harsh environmental conditions. Our results can be applied in obtaining a broad-spectrum, airborne pathogen prevention device in preparation for epidemic and pandemic of respiratory diseases.

A set of surfaces with different Cassie fractions were fabricated. For a given Cassie fraction surfaces had different pillar diameter and spacing combinations. Advancing and receding contact angles of both water and ethylene glycol were measured on the fabricated surfaces. We examined the effects of both surface feature size and Cassie fraction on advancing and receding contact angles and found no relationship between size and contact angle when Cassie fraction was held constant. Also examined was the effect of the Cassie fraction on contact angle hysteresis, which led to the development of a new theoretical framework for understanding contact angle hysteresis on rough surfaces that helps unite previous theory and observations with current observations. The theoretical framework includes empirically determined contact-line pinning forces. From measurements, we found a constant contact-line pinning force for the receding contact angles. For the advancing contact angles, there was also a contact-line pinning force, but one that changed with changing Cassie fraction.

There exist textured surfaces that demonstrate large advancing contact angles when the expected behavior is complete wetting due to high Wenzel roughness. The roughness can represent an impediment to the motion of the contact line, leading to the possibility of contact line pinning and thus increased advancing contact angle. A set of fabricated textured surfaces with varying pillar diameters and pillar spacing were tested using hexadecane. Because of the low surface tension of hexadecane, the majority of the surfaces exhibited penetration of the liquid into the roughness, also known as the Wenzel state. Because of this penetration, the empirical pinning force framework we previously developed for wetting behavior on smooth surfaces and surfaces with texture where liquid does not penetrate the roughness was expanded to include the Wenzel state. For the surfaces that had Wenzel wetting, the receding contact angle tended to follow the predictions of the Wenzel equation, while the advancing contact angle tended to increase with increasing roughness when according to the Wenzel equation it would be expected to decrease. For surfaces where nonpenetrated Cassie wetting was observed, a constant high advancing contact angle and a receding contact angle that follows the trend predicted by the Cassie equation were observed.

A set of surfaces featuring pillars with overhanging cap structures, exhibiting superoleophobic behavior, were fabricated using a new method. While such structures have been previously reported, in contrast with previous literature this new method allows for the control of pillar cross-sectional diameter, pillar separation, and Cassie fraction independent from the pillar radius-to-height ratio. Once fabricated the contact angles of the surfaces were examined using water, ethylene glycol, and hexadecane. These surfaces were capable of maintaining a stable Cassie state with hexadecane where surfaces with similar Cassie fraction but vertical sidewalls we had examined previously collapsed into the Wenzel state. The overall behavior of the liquids conforms to prior experience with vertical sidewall structures, with the advancing contact angles tending to remain high and insensitive to changing Cassie fraction while the receding contact angles follow the trends predicted by the Cassie equation much more closely. All experimental evidence taken together, this seems to indicate that the cap structures increase the stability of the Cassie state, but at the expense of increasing drop pinning, over and above what such surface texturing already does.

This review is devoted to discussing the application of microfabrication technologies to target challenges encountered in life processes by the development of drug delivery systems. Recently, microfabrication has been largely applied to solve health and pharmaceutical science issues. In particular, fabrication methods along with compatible materials have been successfully designed to produce multifunctional, highly effective drug delivery systems. Microfabrication offers unique tools that can tackle problems in this field, such as ease of mass production with high quality control and low cost, complexity of architecture design and a broad range of materials. Presented is an overview of silicon- and polymer-based fabrication methods that are key in the production of microfabricated drug delivery systems. Moreover, the efforts focused on studying the biocompatibility of materials used in microfabrication are analyzed. Finally, this review discusses representative ways microfabrication has been employed to develop systems delivering drugs through the transdermal and oral route, and to improve drug eluting implants. Additionally, microfabricated vaccine delivery systems are presented due to the great impact they can have in obtaining a cold chain-free vaccine, with long-term stability. Microfabrication will continue to offer new, alternative solutions for the development of smart, advanced drug delivery systems.