Comparison of piezoresistive monofilament polymer sensors.

The development of flexible polymer monofilament fiber strain sensors have many applications in both wearable computing (clothing, gloves, etc.) and robotics design (large deformation control). For example, a high-stretch monofilament sensor could be integrated into robotic arm design, easily stretching over joints or along curved surfaces. As a monofilament, the sensor can be woven into or integrated with textiles for position or physiological monitoring, computer interface control, etc. Commercially available conductive polymer monofilament sensors were tested alongside monofilaments produced from carbon black (CB) mixed with a thermo-plastic elastomer (TPE) and extruded in different diameters. It was found that signal strength, drift, and precision characteristics were better with a 0.3 mm diameter CB/TPE monofilament than thick (~2 mm diameter) based on the same material or commercial monofilaments based on natural rubber or silicone elastomer (SE) matrices.

Bioprinting of Stable Bionic Interfaces Using Piezoresistive Hydrogel Organoelectronics.

Bionic tissues offer an exciting frontier in biomedical research by integrating biological cells with artificial electronics, such as sensors. One critical hurdle is the development of artificial electronics that can mechanically harmonize with biological tissues, ensuring a robust interface for effective strain transfer and local deformation sensing. In this study, a highly tissue-integrative, soft mechanical sensor fabricated from a composite piezoresistive hydrogel. The composite not only exhibits exceptional mechanical properties, with elongation at the point of fracture reaching up to 680%, but also maintains excellent biocompatibility across multiple cell types. Furthermore, the material exhibits bioadhesive qualities, facilitating stable cell adhesion to its surface. A unique advantage of the formulation is the compatibility with 3D bioprinting, an essential technique for fabricating stable interfaces. A multimaterial sensorized 3D bionic construct is successfully bioprinted, and it is compared to structures produced via hydrogel casting. In contrast to cast constructs, the bioprinted ones display a high (87%) cell viability, preserve differentiation ability, and structural integrity of the sensor-tissue interface throughout the tissue development duration of 10 d. With easy fabrication and effective soft tissue integration, this composite holds significant promise for various biomedical applications, including implantable electronics and organ-on-a-chip technologies.

Charged-cellulose nanofibrils as a nutrient carrier in biodegradable polymers for enhanced efficiency fertilizers.

An enhanced efficiency fertilizer (EEF) is essential for sustainable agriculture, and here, we evaluated cellulose nanofibrils (CNF) as a nutrient carrier dispersed in biodegradable polymeric matrices. CNF were functionalized with negative (CNF-) and positive (CNF+) charges to improve (i) the CNF-nutrient and (ii) the CNF-polymeric matrix interactions. The CNF encapsulated the KNO3 nutrient by spray drying (microcapsules) and then inserted into a poly (hydroxybutyrate)/starch-based matrix by melt-compounding (tablets). These materials were morphologically, structurally, and thermally characterized before and after biodegradation. Nutrient release profiles showed the microcapsules released the nutrients for up to 1 h, while the tablets did for 8 h in water and over 80 days in soil. Tablets with CNF- released NO3- faster than K+, and those with CNF+ behaved inversely. Besides, the biodegradation efficiencies were up to 75 % in 120 days. The CNF charges affected nutrient release and the matrix biodegradation, ensuring the matrices were harmless to the environment.

Debinding mechanisms in thermoplastic processing of a Ba(0.5)Sr(0.5)Co(0.8)Fe(0.2)O(3-δ)- stearic acid-polystyrene mixture.

In the present study, we address the interaction between a thermoplastic binder system and Ba(0.5)Sr(0.5)Co(0.8)Fe(0.2)O(3-δ) (BSCF) during thermal treatment of the thermoplastic feedstock. BSCF powder was coated with different amounts of stearic acid (SA) acting as a surfactant. Oxygen release from the uncoated BSCF surface changes the decomposition of polystyrene (PS) in inert atmospheres from a pyrolytic to a thermoxidative mechanism, thereby decreasing the break-down temperature and the activation energy. In mixtures with coated BSCF powder, the decomposition products of SA carbonatize the BSCF surface, which inhibits oxygen release. Mass spectrometry of the breakdown products indicates that the decomposition of SA in the presence of BSCF also modifies the decomposition pathway of PS. The influence of BSCF on the polymer decomposition reaction in air is not as strong. Oxygen diffusion seems to be responsible for the differences to pure PS in reaction rates and the activation energies.