Since the outbreak of the severe respiratory disease caused by the novel coronavirus (COVID-19), the use of face masks has become ubiquitous worldwide to control the rapid spread of this pandemic. As a result, the world is currently facing a face mask shortage, and some countries have placed limits on the number of masks that can be bought by each person. Although the surgical grade N95 mask provides the highest level of protection currently available, its filtration efficiency for sub-300 nm particles is around 85% due to its wider pore size (∼300 nm). Because the COVID-19 virus shows a diameter of around 65–125 nm, there is a need for developing more efficient masks. To overcome these issues, we demonstrate the development of a flexible, nanoporous membrane to achieve a reusable N95 mask with a replaceable membrane and enhanced filtration efficiency. We first developed a flexible nanoporous Si-based template on a silicon-on-insulator wafer using KOH etching and then used the template as a hard mask during a reactive ion etching process to transfer the patterns onto a flexible and lightweight (<0.12 g) polymeric membrane. Pores with sizes down to 5 nm were achieved with a narrow distribution. Theoretical calculations show that airflow rates above 85 L/min are possible through the mask, which confirms its breathability over a wide range of pore sizes, densities, membrane thicknesses, and pressure drops. Finally, the membrane is intrinsically hydrophobic, which contributes to antifouling and self-cleaning as a result of droplets rolling and sliding on the inclined mask area.

Current marine research primarily depends on weighty and invasive sensory equipment and telemetric network to understand the marine environment, including the diverse fauna it contains, as a function of animal behavior and size, as well as equipment longevity. To match animal morphology and activity within the surrounding marine environment, here we show a physically flexible and stretchable skin-like and waterproof autonomous multifunctional system, integrating Bluetooth, memory chip, and high performance physical sensors. The sensory tag is mounted on a swimming crab (Portunus pelagicus) and is capable of continuous logging of depth, temperature, and salinity within the harsh ocean environment. The fully packaged, ultra-lightweight (<2.4 g in water), and compliant "Marine Skin" system does not have any wired connection enabling safe and weightless cuttingedge approach to monitor and assess marine life and the ecosystem's health to support conservation and management of marine ecosystems.

Advances in marine research to understand environmental change and its effect on marine ecosystems rely on gathering data on species physiology, their habitat, and their mobility patterns using heavy and invasive biologgers and sensory telemetric networks. In the past, a lightweight (6 g) compliant environmental monitoring system: Marine Skin was demonstrated. In this paper, an enhanced version of that skin with improved functionalities (500–1500% enhanced sensitivity), packaging, and most importantly its endurance at a depth of 2 km in the highly saline Red Sea water for four consecutive weeks is reported. A unique noninvasive approach for attachment of the sensor by designing a wearable, stretchable jacket (bracelet) that can adhere to any species irrespective of their skin type is also illustrated. The wearable featherlight (<0.5 g in air, 3 g with jacket) gadget is deployed on Barramundi, Seabream, and common goldfish to demonstrate the noninvasive and effective attachment strategy on different species of variable sizes which does not hinder the animals' natural movement or behavior.

Point-of-care testing (POC) has the ability to detect chronic and infectious diseases early or at the time of occurrence and provide a state-of-the-art personalized healthcare system. Recently, wearable and flexible sensors have been employed to analyze sweat, glucose, blood, and human skin conditions. However, a flexible sensing system that allows for the real-time monitoring of throat-related illnesses, such as salivary parotid gland swelling caused by flu and mumps, is necessary. Here, for the first time, a wearable, highly flexible, and stretchable piezoresistive sensing patch based on carbon nanotubes (CNTs) is reported, which can record muscle expansion or relaxation in real-time, and thus act as a next-generation POC sensor. The patch offers an excellent gauge factor for in-plane stretching and spatial expansion with low hysteresis. The actual extent of muscle expansion is calculated and the gauge factor for applications entailing volumetric deformations is redefined. Additionally, a bluetooth-low-energy system that tracks muscle activity in real-time and transmits the output signals wirelessly to a smartphone app is utilized. Numerical calculations verify that the low stress and strain lead to excellent mechanical reliability and repeatability. Finally, a dummy muscle is inflated using a pneumatic-based actuator to demonstrate the application of the affixed wearable next-generation POC sensor.

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We present a flexible acoustic sensor that has been designed to detect wheezing (a common symptom of asthma) while attached to the chest of a human. We adopted a parallel plate capacitive structure using air as the dielectric material. The pressure (acoustic) waves from wheezing vibrate the top diaphragm of the structure, thereby, changing the output capacitance. The sensor is designed such that it resonates in the frequency range of wheezing (100-1000Hz) which presents twofold benefits. The resonance results in large deflection of the diaphragm that eradicates the need for using signal amplifiers (used in microphones). Secondly, the design itself acts as a low pass filter to reduce the effect of background noise which mostly lies in >1000Hz frequency range. The resulting analog interface is minimal and thus, consumes less power and occupies less space. The sensor is made up of low-cost sustainable materials (aluminum foil) which greatly reduces the cost and complexity of manufacturing processes. A robust wheezing detection (Matched filter) algorithm is used to identify different types of wheezing sounds among the noisy signals originating from the chest that lie in the same frequency range as wheezing. The sensor is connected to a smartphone via Bluetooth, enabling signal processing and further integration into digital medical electronic systems based on the Internet of Things (IoT). Bending, cyclic pressure, heat, and sweat tests are performed on the sensor to evaluate its performance in simulated real-life harsh conditions.

Monitoring, measuring and controlling electronic systems in space exploration, automotive industries, downhole oil and gas industries, oceanic environment, geothermal power plants, etc. require materials and processes that can withstand harsh environments. Such harshness can come from the surrounding temperature, varying pressure, intense radiation, reactive chemicals, humidity, salinity, or a combination of any of these conditions. Here, we review recent progress in the development of flexible and stretchable electronic devices for harsh environment applications. We consider studies on how the selection of a specific material is important for a specific application and how the selection of the material plays critical role in sustained performance. We present specific examples for selected applications. We also look at works on methods and designs for achieving flexibility and stretchability in devices designed for harsh environments. Finally, we look at studies on Powered by Editorial Manager® and ProduXion Manager® from Aries Systems Corporation packaging techniques that enable deployment of conventional electronic devices in harsh environment applications and offer a few examples.

Molybdenum disulphide (MoS2) is an emerging 2‐dimensional (2D) semiconductor for electronic devices. However, unstable and low performance of MoS2 FETs is an important concern. In this study, inserting an atomic layer deposition (ALD) titanium dioxide (TiO2) interfacial layer between contact metal and MoS2 channel is suggested to achieve more stable performances. The reduced threshold voltage (VTH) shift and reduced series resistance (RSD) were simultaneously achieved.