Carbon nanotube yarns are employed to develop environment-friendly, low cost and lightweight paper-based flexible devices for wearable applications in temperature and respiratory monitoring, and personal healthcare.

This paper reports on the thermoresistive properties of graphite on paper (GOP). A negative temperature coefficient of resistance (TCR) from −2900 to −4400 ppm K⁻¹ was observed for the GOP. This negative and large TCR is attributed to an increase in the thermionic emission current over a low potential barrier with increasing temperature. The potential barrier was found to be 33 meV between the graphite grains. The paper also demonstrates the use of the GOP in a highly sensitive (0.83 mV (m s⁻¹)^−0.8 mW⁻¹) GOP-based anemometer, indicating strong feasibility of using this material for low-cost and sensitive thermal sensing applications.

Cubic silicon carbide is a promising material for Micro Electro Mechanical Systems (MEMS) applications in harsh environ-ments and bioapplications thanks to its large band gap, chemical inertness, excellent corrosion tolerance and capability of growth on a Si substrate. This paper reports the piezoresistive effect of p-type single crystalline 3C-SiC characterized at high temperatures, using anin situmeasurement method. The experimental results show that the highly doped p-type 3C-SiC possesses a relatively stable gauge factor of approximately 25 to 28 at temperatures varying from 300 K to 573 K. Thein situmethod proposed in this study also demonstrated that, the combination of the piezoresistive and thermoresistive effects can increase the gauge factor of p-type 3C-SiC to approximately 20% at 573 K. The increase in gauge factor based on the combination of these phenomena could enhance the sensitivity of SiC based MEMS mechanical sensors.

In this paper, we report on a low-cost, environment-friendly and wearable thermal flow sensor, which can be manufactured in-house using pencil graphite as a sensing hot film and biodegradable printing paper as a substrate, without using any toxic solvents or cleanroom facilities. The hot film flow sensor offers excellent performance such as high signal-to-noise ratio ( ⩾ 40 for an air flow velocity of 1 m s ⁻¹ ), high sensitivity to airflow (53.7 mV(m s ⁻¹ ) ^−0.8 ) and outstanding long-term stability (almost no drift in 24 h). The sensor can be comfortably affixed to the philtrum of patients and measures human respiration in realtime. The results indicate that the wearable thermal flow sensors fabricated by this solvent-free and user-friendly method could be employed in human respiratory monitoring.

This letter reports on the piezoresistive effect of top-down fabricated 3C-SiC nanowires (NWs). Focused ion beam was utilized to create p-type 3C-SiC NWs from a 3C-SiC thin film with a carrier concentration of 5 × 10 ¹⁸ cm ^-3 epitaxially grown on a Si substrate. The as-fabricated NWs were then subjected to tensile strains varying from 0 to 280 με. Experimental data showed that the p-type 3C-SiC NWs possess a large gauge factor of 35, which is at least one order of magnitude larger than that of other hard materials, such as carbon nanotubes and graphene. This large gauge factor and the linear relationship between the relative resistance change and the applied strain in the SiC NWs indicate their potential for nanoelectromechanical systems sensing applications.