Wireless Sensor for Meat Freshness Assessment Based on Radio Frequency Communication.

Wireless communication technologies, particularly radio frequency (RF), have been widely explored for wearable electronics with secure and user-friendly information transmission. By exploiting the operational principle of chemically actuated resonant devices (CARDs) and the electrical response observed in chemiresistive materials, we propose a simple and hands-on alternative to design and manufacture RF tags that function as CARDs for wireless sensing of meat freshness. Specifically, the RF antennas were meticulously designed and fabricated by lithography onto a flexible substrate with conductive tape, and the RF signal was characterized in terms of amplitude and peak resonant frequency. Subsequently, a single-walled carbon nanotube (SWCNT)/MoS2/In2O3 chemiresistive composite was incorporated into the RF tag to convey it as CARDs. The RF signal was then utilized to establish a correlation between the sensor's electrical response and the RF attenuation signal (reflection coefficient) in the presence of volatile amines and seafood (shrimp) samples. The freshness of the seafood samples was systematically assessed throughout the storage time by utilizing the CARDs, thereby underscoring their effective potential for monitoring food quality. Specifically, the developed wireless tags provide cumulative amine exposure data within the food package, demonstrating a gradual decrease in radio frequency signals. This study illustrates the versatility of RF tags integrated with chemiresistors as a promising pathway toward scalable, affordable, and portable wireless chemical sensors.

Self-supported nickel nanoparticles on germanophosphate glasses: synthesis and applications in catalysis.

The development of supported catalysts based on simple procedures without waste products and time-consuming steps is highly desirable. In this paper, self-supported nickel-based nanoparticles were obtained at the surface of the germanophosphate glasses by bottom-up process and evaluated as potential catalysts for the benzyl alcohol oxidation and bis(indolyl)methanes synthesis. A classical melt-quenching technique was used for preparing the nickel-doped germanophosphate glasses, followed by annealing under a hydrogen atmosphere at 400 °C for two different times. The approach enabled the synthesis of self-supported nanoparticles as a homogeneous film, covering the glass surface. The physical and chemical properties of synthesized glasses were characterized by UV-vis and Raman spectroscopies and thermal analysis. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were performed to monitor the growth process, morphology and chemical bonding structure of the nanoparticles surface.