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This study introduces the development of a photothermal-based microfluidic paper analytical device (PT-µPAD) integrated with near-field communication (NFC) technology and smartphone readout for enzyme-free glucose quantification in human samples. With the properties of gold nanoparticles (AuNPs) both as a nanozyme and as a photothermal substrate, there is no need for costly reagents like enzymes or a readout instrumentation for the selective and sensitive detection of glucose. In PT-µPADs, AuNPs are etched by hydrogen peroxide (H2O2) generated from glucose catalysis. Photothermal detection from the plasmonic heating of these AuNPs when illuminated by a 533nm LED light source is achieved by inserting the PT-µPAD sensor into a portable NFC platform suitable for smartphone readout. Temperature variation is directly proportional to the glucose concentration. After optimization, we acquired a linear range between 5.0 and 20.0 µmol L−1 (R2 = 0.9967) and a limit of detection (LOD) of 25.0 nmol L−1 for glucose. Additionally, while our sensor does not utilize any enzyme, it is remarkably selective to glucose with no effects from interferences. Recovery studies in various human control samples indicated a range of 99.73–102.66% with the highest RSD of 3.53%, making it highly accurate and precise. Moreover, our method is more sensitive than other methods relying on conventional µPADs for glucose sensing. By integrating the potential benefits of microfluidics, nanomaterials as nanozymes, and NFC technology for wireless readout, our sensor demonstrates great promise as an accessible, affordable, and shelf-stable device for glucose quantification. Moreover, this concept can be extended to detect other molecules of interest as a point-of-care (POC) diagnostics device. [ABSTRACT FROM AUTHOR]

There exists a strong correlation between the pH levels of the gastrointestinal (GI) tract and GI diseases such as inflammatory bowel disease (IBS), ulcerative colitis, and pancreatis. Existing methods for diagnosing many GI diseases predominantly rely on invasive, expensive, and time-consuming techniques such as colonoscopy and endoscopy. In this study, an autonomous ingestible smart biosensing system in a pill format with integrated pH sensors is reported. The smart sensing pills will measure the pH profile as they transit through the GI tract. The data is then downloaded from the pills after they are collected from the feces. The sensor is based on electrodeposited PANI on carbon-coated conductive threads providing high pH sensitivity. Engineering innovations allowed integration of thread-based sensors on 3D-printed pill surfaces with front-end readout electronics, memory, and microcontroller assembled on mm-size circular printed circuit boards. The entire smart sensing pill possesses an overall length of 22.1 mm and an outer diameter of 9 mm. The modular biosensing system allows integration of thread-based biosensors to monitor other biomarkers in GI tract that mitigates the complex sensor fabrication process as well as overall pill assembly. [ABSTRACT FROM AUTHOR]

There is a need to develop low-cost and compact frequency reconfigurable antennas with continuous frequency tuning capability. Existing approaches rely on dedicated electrical, mechanical, or MEMS-based approaches to reconfigure the antenna, which requires extra components and fabrication steps. In this paper, we propose a physics-based approach to realize tunable helical antennas based on a shape memory alloy (SMA). By utilizing the temperature-induced irreversible mechanical deformation of the SMA, the temperature-controlled antenna can continuously change its resonant frequency and lock the state when the desired frequency response is achieved. The height of the helical antenna changes in response to applied temperatures. No additional circuitry or mechanical modules are required for the reconfiguration of the antenna geometry. The fabricated helical antenna can shift resonant frequency between 150 and 195 MHz with a tuning sensitivity of 284 kHz/°C. [ABSTRACT FROM AUTHOR]

There is a need to develop cost-effective and compact solutions for Smart Home monitoring. Existing monitoring systems depend on continuous power sources to support the operation of sensors and electronics modules used therein. In this article, we present three simple battery-free, Radio-Frequency Identification (RFID)-based solutions for real-time monitoring of the orientation of an object using a tilt sensor based on a metallic bead, an entry detection system utilizing a reed switch-based proximity sensor, and a temperature crossing event detection using a thermistor. All sensors are integrated with individual passive RFID tags. The proposed sensing mechanisms were also combined to achieve multi-modal logic sensing operation. Active events (change in position, motion, and temperature) would alter the state of the corresponding flexible RFID sensors to transmit warning signals wirelessly to an RFID reader, realizing a simple RFID-based Smart Home network. The proposed platform has been validated through extensive simulation and actual measurements. [ABSTRACT FROM AUTHOR]

Wearables have garnered significant attention in recent years not only as consumer electronics for entertainment, communications, and commerce but also for real-time continuous health monitoring. This has been spurred by advances in flexible sensors, transistors, energy storage, and harvesting devices to replace the traditional, bulky, and rigid electronic devices. However, engineering smart wearables that can seamlessly integrate with the human body is a daunting task. Some of the key material attributes that are challenging to meet are skin conformability, breathability, and biocompatibility while providing tunability of its mechanical, electrical, and chemical properties. Electrospinning has emerged as a versatile platform that can potentially address these challenges by fabricating nanofibers with tunable properties from a polymer base. In this article, we review advances in wearable electronic devices and systems that are developed using electrospinning. We cover various applications in multiple fields including healthcare, biomedicine, and energy. We review the ability to tune the electrical, physiochemical, and mechanical properties of the nanofibers underlying these applications and illustrate strategies that enable integration of these nanofibers with human skin. [ABSTRACT FROM AUTHOR]

In this article, we present a magnetically–tunable quad–band filter with high tunability in the frequency range of 2.1–3.9 GHz. A multi–band filter with four stop–bands comprises of a microstrip line coupled to four frequency–selective split–ring resonators (SRRs). We achieve tuning of individual frequency bands using magnetic reed switches connected in between the capacitive gaps of each split–ring resonator. Application of magnetic field tunes this capacitance affecting its resonance frequency. The measured reflection spectrum of the proposed device matches well with the simulation results. The results show more than 25% tunability for each of the four bands with bandwidth values in the range of 30–70 MHz with over 100% overall tunability in the 2.1–3.9 GHz frequency spectrum. [ABSTRACT FROM AUTHOR]