Search for: All records

A recurring challenge in extracting energy from ambient motion is that devices must maintain high harvesting efficiency and a positive user experience when the interface is undergoing dynamic compression. We show that small amphiphiles can be used to tune friction, haptics, and triboelectric properties by assembling into specific conformations on the surfaces of materials. Molecules that form multiple slip planes under pressure, especially through π-π stacking, produce 80 to 90% lower friction than those that form disordered mesostructures. We propose a scaling framework for their friction reduction properties that accounts for adhesion and contact mechanics. Amphiphile-coated surfaces tend to resist wear and generate distinct tactile perception, with humans preferring more slippery materials. Separately, triboelectric output is enhanced through the use of amphiphiles with high electron affinity. Because device adoption is tied to both friction reduction and electron-withdrawing potential, molecules that self-organize into slippery planes under pressure represent a facile way to advance the development of haptic power harvesters at scale. 

Abstract Bio-inspired, micro/nanotextured surfaces have a variety of applications including superhydrophobicity, self-cleaning, anti-icing, antibiofouling, and drag reduction. In this paper, a template-free and scalable roll coating process is studied for fabrication of micro/nanoscale topographies surfaces. These micro/nanoscale structures are generated with viscoelastic polymer nanocomposites and derived by controlling ribbing instabilities in forward roll coating. The relationship between process conditions and surface topography is studied in terms of shear rate, capillary number, and surface roughness parameters (e.g., Wenzel factor and the density of peaks). For a given shear rate, the sample roughness increased with a higher capillary number until a threshold point. Similarly, for a given capillary number, the roughness increased up to a threshold range associated with shear rate. A peak density coefficient (PDC) model is proposed to relate capillary number and shear rate to surface roughness. The optimum range of the shear rate and the capillary number was found to be 40–60 s−1 and 4.5 × 105–6 × 105, respectively. This resulted in a maximum Wenzel roughness factor of 1.91, a peak density of 3.94 × 104 (1/mm2), and a water contact angle (WCA) of 128 deg. 

Our Accessibility Learning Labs not only inform participants about the need for accessible software, but also how to properly create and implement accessible software. These experiential browser-based labs enable participants, instructors and practitioners to engage in our material using only their browser. In the following document, we will provide a brief overview of our labs, how they may be adopted, and some of their preliminary results. Complete project material is publicly available on our project website: http://all.rit. edu 

Our Accessibility Learning Labs not only inform participants about how to properly create accessible software, but also demonstrate the need to create accessible software. These experiential browser-based activities enable students, instructors and practitioners to utilize the material using only their browser. This tutorial will benefit a wide-range of participants in the software engineering community, from students to experienced practitioners who want to ensure that they are properly creating inclusive, accessible software. Complete project material is publicly available on the project website: http://all.rit.edu 

Abstract Extracellular matrix (ECM) is a complex structure composed of bioactive molecules representative of the local tissue microenvironment. Decellularized ECM biomaterials harness these biomolecules for regenerative medicine applications. One potential therapeutic application is the use of vocal fold (VF) specific ECM to restore the VFs after injury. ECM scaffolds are derived through a process of decellularization, which aims to remove unwanted immunogenic biomolecules (e.g. DNA) while preserving the composition of the ECM. The effectiveness of the decellularization is typically assessed at the end by quantifying ECM attributes such as final dsDNA content. However, batch-to-batch variability in ECM manufacturing remains a significant challenge for the standardization, cost-effectiveness, and scale-up process. The limited number of tools available for in-process control heavily restricts the uncovering of the correlations between decellularization process parameters and ECM attributes. In this study, we developed a technique applicable to both the classical batch method and semi-continuous decellularization systems to trace the decellularization of two laryngeal tissues in real-time. We hypothesize that monitoring the bioreactor’s effluent absorbance at 260 nm as a function of time will provide a representative DNA release profile from the tissue and thus allow for process optimization. The DNA release profiles were obtained for laryngeal tissues and were successfully used to optimize the derivation of VF lamina propria-ECM (auVF-ECM) hydrogels. This hydrogel had comparable rheological properties to commonly used biomaterials to treat VF injuries. Also, the auVF-ECM hydrogel promoted the down-regulation of CCR7 by THP-1 macrophages upon lipopolysaccharide stimulation in vitro suggesting some anti-inflammatory properties. The results show that absorbance profiles are a good representation of DNA removal during the decellularization process thus providing an important tool to optimize future protocols. 

Abstract In oxygen (O₂)‐controlled cell culture, an indispensable tool in biological research, it is presumed that the incubator setpoint equals the O₂tension experienced by cells (i.e., pericellular O₂). However, it is discovered that physioxic (5% O₂) and hypoxic (1% O₂) setpoints regularly induce anoxic (0% O₂) pericellular tensions in both adherent and suspension cell cultures. Electron transport chain inhibition ablates this effect, indicating that cellular O₂consumption is the driving factor. RNA‐seq analysis revealed that primary human hepatocytes cultured in physioxia experience ischemia‐reperfusion injury due to cellular O₂consumption. A reaction‐diffusion model is developed to predict pericellular O₂tension a priori, demonstrating that the effect of cellular O₂consumption has the greatest impact in smaller volume culture vessels. By controlling pericellular O₂tension in cell culture, it is found that hypoxia vs. anoxia induce distinct breast cancer transcriptomic and translational responses, including modulation of the hypoxia‐inducible factor (HIF) pathway and metabolic reprogramming. Collectively, these findings indicate that breast cancer cells respond non‐monotonically to low O₂, suggesting that anoxic cell culture is not suitable for modeling hypoxia. Furthermore, it is shown that controlling atmospheric O₂tension in cell culture incubators is insufficient to regulate O₂in cell culture, thus introducing the concept of pericellular O₂‐controlled cell culture. 

Abstract Periodic micro/nanoscale structures from nature have inspired the scientific community to adopt surface design for various applications, including superhydrophobic drag reduction. One primary concern of practical applications of such periodic microstructures remains the scalability of conventional microfabrication technologies. This study demonstrates a simple template‐free scalable manufacturing technique to fabricate periodic microstructures by controlling the ribbing defects in the forward roll coating. Viscoelastic composite coating materials are designed for roll‐coating using carbon nanotubes (CNT) and polydimethylsiloxane (PDMS), which helps achieve a controllable ribbing with a periodicity of 114–700 µm. Depending on the process parameters, the patterned microstructures transition from the linear alignment to a random structure. The periodic microstructure enables hydrophobicity as the water contact angles of the samples ranged from 128° to 158°. When towed in a static water pool, a model boat coated with the microstructure film shows 7%–8% faster speed than the boat with a flat PDMS film. The CNT addition shows both mechanical and electrical properties improvement. In a mechanical scratch test, the cohesive failure of the CNT‐PDMS film occurs in ≈90% higher force than bare PDMS. Moreover, the nonconductive bare PDMS shows sheet resistance of 747.84–22.66 Ω □⁻¹with 0.5 to 2.5 wt% CNT inclusion.