Development of TiO2-CaCO3 Based Composites as an Affordable Building Material for the Photocatalytic Abatement of Hazardous NOx from the Environment.

This study explores the depollution activity of a photocatalytic cementitious composite comprising various compositions of n-TiO2 and CaCO3. The photocatalytic activity of the CaCO3-TiO2 composite material is assessed for the aqueous photodegradation efficiency of MB dye solution and NOx under UV light exposure. The catalyst CaCO3-TiO2 exhibits the importance of an optimal balance between CaCO3 and n-TiO2 for the highest NOx removal of 60% and MB dye removal of 74.6%. The observed trends in the photodegradation of NOx removal efficiencies suggest a complex interplay between CaCO3 and TiO2 content in the CaCO3-n-TiO2 composite catalysts. This pollutant removal efficiency is attributed to the synergistic effect between CaCO3 and n-TiO2, where a higher percentage of n-TiO2 appeared to enhance the photocatalytic activity. It is recommended that CaCO3-TiO2 photocatalysts are effectiveness in water and air purification, as well as for being cost-effective construction materials.

Materials and Device Designs for Wireless Monitoring of Temperature and Thermal Transport Properties of Wound Beds during Healing.

Chronic wounds represent a major health risk for diabetic patients. Regeneration of such wounds requires regular medical treatments over periods that can extend for several months or more. Schemes for monitoring the healing process can provide important feedback to the patient and caregiver. Although qualitative indicators such as malodor or fever can provide some indirect information, quantitative measurements of the wound bed have the potential to yield important insights. The work presented here introduces materials and engineering designs for a wireless system that captures spatio-temporal temperature and thermal transport information across the wound continuously throughout the healing process. Systematic experimental and computational studies establish the materials aspects and basic capabilities of this technology. In vivo studies reveal that both the temperature and the changes in this quantity offer information on wound status, with indications of initial exothermic reactions and mechanisms of scar tissue formation. Bioresorbable materials serve as the foundations for versions of this device that create possibilities for monitoring on and within the wound site, in a way that bypasses the risks of physical removal.

Solvent-Assisted Filling of Liquid Metal and Its Selective Dewetting for the Multilayered 3D Interconnect in Stretchable Electronics.

As stretchable electronics are rapidly developing and becoming complex, the requirement for stretchable, multilayered, and large-area printed circuit boards (PCBs) is emerging. This demands a stretchable electrode and its vertical interconnect access (via) for 3-dimensional (3D) connectivity between layers. Here, we demonstrate solvent-assisted liquid metal (LM) filling into the submicrometer channel (∼400 nm), including via-hole filling and selective dewetting of LM. We provide the theoretical background of solvent-assisted LM filling and selective dewetting and reveal the osmotic pressure arising from anomalous mass transport phenomena, case II diffusion, which drives negative pressure, the spontaneous pulling of LM into the open channel. Also, we suggest design criteria for the geometry and dimension of LM interconnects to obtain structural stability without dewetting, based on the theoretical and computational background. We demonstrate a simple stretchable near-field communication (NFC) device including transferred micrometer-size light-emitting diodes (LEDs) with only 230 µm to the stretchable liquid metal PCB, without any soldering process. The device operates stably under repetitive stretching and releasing (∼50% uniaxial strain) due to the stable connection through the LM via between the upper and lower layers. Finally, we propose a concept for modular-type stretchable electronics, based on the cohesive liquid nature of LM. As a building block, the functional module can be easily removed from a mainframe, and replaced by another functional module, to suit user demand.

Cuticular pad-inspired selective frequency damper for nearly dynamic noise-free bioelectronics.

Bioelectronics needs to continuously monitor mechanical and electrophysiological signals for patients. However, the signals always include artifacts by patients' unexpected movement (such as walking and respiration under approximately 30 hertz). The current method to remove them is a signal process that uses a bandpass filter, which may cause signal loss. We present an unconventional bandpass filter material-viscoelastic gelatin-chitosan hydrogel damper, inspired by the viscoelastic cuticular pad in a spider-to remove dynamic mechanical noise artifacts selectively. The hydrogel exhibits frequency-dependent phase transition that results in a rubbery state that damps low-frequency noise and a glassy state that transmits the desired high-frequency signals. It serves as an adaptable passfilter that enables the acquisition of high-quality signals from patients while minimizing signal process for advanced bioelectronics.

Gelatin Hydrogel-Based Organic Electrochemical Transistors and Their Integrated Logic Circuits.

We suggest gelatin hydrogel as an electrolyte and demonstrate organic electrochemical transistors (OECTs) based on a sheet of gelatin. We also modulate electrical characteristics of the OECT with respect to pH condition of the gelatin hydrogel from acid to base and analyze its characteristics based on the electrochemical theory. Moreover, we extend the gelatin-based OECT to electrochemical logic circuits, for example, NOT, NOR, and NAND gates.

Biosafe, Eco-Friendly Levan Polysaccharide toward Transient Electronics.

New options in the material context of transient electronics are essential to create or expand potential applications and to progress in the face of technological challenges. A soft, transparent, and cost-effective polymer of levan polysaccharide that is capable of complete, programmable dissolution is described when immersed in water and implanted in an animal model. The results include chemical analysis, the kinetics of hydrolysis, and adjustable dissolution rates of levan, and a simple theoretical model of reactive diffusion governed by temperature. In vivo experiments of the levan represent nontoxicity and biocompatibility without any adverse reactions. On-demand, selective control of dissolution behaviors with an animal model demonstrates an effective triggering strategy to program the system's lifetime, providing the possibility of potential applications in envisioned areas such as bioresorbable electronic implants and drug release systems.