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Animal‐borne biologging technology allows researchers to understand the physiological responses of wild animals, especially songbirds, to environmental changes. Songbirds are of interest in studying these responses because of their visibility and relatively small body size yet high energetic demand of their various life‐history stages (e.g., molt, migration, breeding). Previous methods for monitoring responses, such as heart rate activity, have relied on surgical implantation of electrodes connected to bulky electronic devices which affect the well‐being of birds, indirectly influence bird behavior and create stress artifacts. A non‐invasive, lightweight solution is needed. This study introduces eutectogels, a long‐lasting gel made from deep eutectic solvents, combined with conductive threads and a wireless device to monitor the heart rate of house sparrows noninvasively through skin contact. In this work, heart rate and respiration rate measurements are validated on birds under anesthesia. These tests are repeated on birds that are awake but restrained. The eutectogel outperforms commercial electrodes and gels, yielding high signal‐to‐noise ratio measurements on restrained birds. The respiration rate is extracted and processed electronically from motion artifacts in the recorded signals without the need for a separate dedicated sensor. The system shows promise for future field studies on free‐living species. [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]

• Shared operational amplifier-based readout capable of multimodal measurements. • Lightweight, multiplexed electrochemical sensors on flexible textile threads. • Miniaturized sensing platform for multiple analyte detection. • Probe platform validation with oxygen and pH monitoring. High throughput screening (HTS) based on microwell (or bioreactor) arrays is a well-established approach for rapid screening and identification of lead molecules or target analytes for drug discovery and other applications in biotechnology. However, it has been challenging to scale up these platforms due to the lack of integrated sensors to monitor the microenvironment of each microwell in the array needed. In this work, we present a practical solution for a miniaturized multiplexed sensing system with integrated circuitry capable of performing continuous electrochemical potentiometric and amperometric measurements. The platform uses lightweight multiplexed electrochemical sensors implemented on thin textile threads, all of which share a single operational amplifier (op-amp) and a switch network for both voltage and current measurements. The resulting platform forgoes the need for large-area sensors or bulky multichannel potentiostat with a simple readout circuitry capable of multimodal measurements. The design and validation of the multiplexed sensing system have been reported in the context of measuring pH and oxygen (O 2), which are crucial biomarkers for any HTS application. The thread-based pH and O 2 sensors possess sensitivities of ∼65.87 mV/pH for the pH sensor (n = 3) and 0.6621 nA/mg L-1 for the O 2 sensor (n = 3). This architecture is modular such that it can be easily extended to monitoring multiple biomarkers employing thread-based sensors and sharing the same readout circuitry, making it a practical and versatile tool for biotechnology research. [Display omitted] [ABSTRACT FROM AUTHOR]

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]

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]

Technologies capable of noninvasively sampling different locations in the gut upstream of the colon will enable new insights into the role of organ‐specific microbiomes on human health. Herein, an ingestible pill for the sampling of gut lumen based on one of the earliest hydraulic machines known as an Archimedes screw is reported. The design contains twisted wires as Archimedes screw driven by a motor, wirelessly activated using a magnet. The sampling performance of the screw‐pump pill is characterized using realistic in vitro models and validated in vitro using E. coli expressing different fluorescent proteins. The use of the Archimedes screw enables the pill to sample the dense GI environment. The pill is also tested ex vivo in the pig intestine and in vivo in pigs. Herein, the results show that the bacterial populations recovered from the pill's chamber closely resemble the targeted bacterial population of the microenvironment to which the pill is exposed. Such ingestible devices have the potential to revolutionize the understanding of the spatial diversity of the gut microbiome and its response to medical conditions and treatments. [ABSTRACT FROM AUTHOR]