High-performance electromagnetic interference shielding is becoming vital for the next generation telecommunication and sensor devices among which portable and wearable applications require highly flexible and lightweight materials having efficient absorption-dominant shielding. Herein, we report on lightweight carbon foam-carbon nanotube/carbon nanofiber nanocomposites that are synthesized in a two-step robust process including a simple carbonization of open-pore structure melamine foams and subsequent growth of carbon nanotubes/nanofibers by chemical vapor deposition. The microstructure of the nanocomposites resemble a 3-dimensional hierarchical network of carbonaceous skeleton surrounded with a tangled web of bamboo-shaped carbon nanotubes and layered graphitic carbon nanofibers. The microstructure of the porous composite enables absorption-dominant (absorbance ~0.9) electromagnetic interference shielding with an effectiveness of ~20-30 dB and with an equivalent mass density normalized shielding effectiveness of ~800-1700 dB cm³ g^-1 at the K-band frequency (18-26.5 GHz). Moreover, the hydrophobic nature of the materials grants water-repellency and stability in humid conditions important for reliable operation in outdoor use; whereas the mechanical flexibility and durability with excellent piezoresistive behavior enable strain-responsive tuning of electrical conductivity and electromagnetic interference shielding, adding on further functionalities. The demonstrated nanocomposites are versatile and will contribute to the development of reliable devices not only in telecommunication but also in wearable electronics, aerospace engineering and robotics among others.

Stretchable and wearable strain sensors have been intensively studied in recent years for applications in human motion monitoring. However, achieving a high-performance strain sensor with high stretchability, ultra-sensitivity, and functionality, such as tunable sensing ranges and sensitivity to various stimuli, has not yet been reported, even though such sensors have great importance for the future applications of wearable electronics. Herein, a novel and versatile strain sensor based on a cracking (silver ink patterned silicone elastomer)-(silver plated nylon structure) (Ag-DS/CF) has been designed and fabricated. The unique structure combined precisely shaped stretchable conductive fabrics and wrinkled Ag-ink pattern to achieve an excellent electrical performance. The Ag-DS/CF could be used to detect both large and subtle human motions and activities, pressure changes, and physical vibrations by achieving high stretchability up to 75%, ultrahigh sensitivity (gauge factor >10⁴–10⁶), tunable sensing ranges (from 7 to 75%). Excellent durability was demonstrated for human motion monitoring with machine washability. The extremely versatile Ag-DS/CF showed outstanding potential for the future of wearable electronics in real-time monitoring of human health, sports performance, etc.

The development of flexible and stretchable sensing for future applications, e.g., strain, force, and pressure, requires novel foam and foam-like structures with properties such as fast relaxation times, a wide linear response range, good sensitivity to different stimuli and repeatability, without compromising low-cost, simple and effective manufacturing methods, and excellent mechanical properties. We present a new type of hybrid foam pressure sensor that utilizes a combination of piezoresistive and capacitive sensor elements. The hybrid foam sensor shows a maximum pressure sensitivity of 0.338 kPa ^-1 and a linear response of 0.049 kPa ^- 1 in the piezoresistive and capacitive sensor elements, respectively, in the pressure ranges of <;5 and 0-240 kPa, respectively. The response and recovery times of both sensor elements were similar, ≤200 ms, at various pressures. In addition, the properties of the hybrid foam sensors, e.g., sensitivity and response and recovery times, can be tuned in various ways, such as by changing the thickness of the composition of the foam. In addition, the materials are easily accessible and the sensor can be cost-effectively manufactured and changed for different purposes. The relatively high sensitivity of the piezoresistive sensor element enables object manipulation from low pressure (≥21 Pa) to high pressure (>80 kPa). Simultaneously, both the sensor elements can be used for impact measurements across a wide range of pressures up to ≥240 kPa. Thus, the concept of the hybrid foam sensor could be utilized widely for sensing of pressures, impacts, or even bending in various applications, e.g., wearable electronics.

The use of face masks is an important way to fight the COVID-19 pandemic. In this paper, we envision the Smart Mask, an IoT supported platform and ecosystem aiming to prevent and control the spreading of COVID-19 and other respiratory viruses. The integration of sensing, materials, AI, wireless, IoT, and software will help the gathering of health data and health-related event detection in real time from the user as well as from their environment. In the larger scale, with the help of AI-based analysis for health data it is possible to predict and decrease medical costs with accurate diagnoses and treatment plans, where the comparison of personal data to large-scale public data enables drawing up a personal health trajectory, for example. Key research problems for smart respiratory protective equipment are identified in addition to future research directions. A Smart Mask prototype was developed with accompanying user application, backend and heath AI to study the concept.