Textile triboelectric nanogenerators for human respiratory monitoring with machine washability are developed through loom weaving of Cu-PET and PI-Cu-PET yarns. Triboelectric charges are generated at the yarn crisscross intersections to achieve a maximum short circuit current density of 15.50 mA m . By integrating into a chest strap, human respiratory rate and depth can be monitored.

Flexible pressure sensors play an important role in electronic skins (E-Skins), which mimic the mechanical forces sensing properties of human skin. A rational design for a pressure sensor with adjustable characteristics is in high demand for different application scenarios. Here, we present tunable, ultrasensitive, and flexible pressure sensors based on compressible wrinkled microstructures. Modifying the morphology of polydimethylsiloxane (PDMS) microstructure enables the device to obtain different sensitivities and pressure ranges for different requirements. Furthermore, by intentionally introducing hollow structures in the PDMS wrinkles, our pressure sensor exhibits an ultrahigh sensitivity of 14.268 kPa–1. The elastic microstructure-based capacitive sensor also possesses a very low detectable pressure limit (1.5 Pa), a fast response time (<50 ms), a wide pressure range, and excellent cycling stability. Implementing respiratory monitoring and vocalization recognition is realized by attaching the flexible pressure sensor onto the chest and throat, respectively, showing its great application potential for disease diagnosis, monitoring, and other advanced clinical/biological wearable technologies.

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Poly(vinylidene fluoride) (PVDF) was electrospun into fibrous membranes from its solutions in a mixture of N,N-dimethylformamide (DMF) and acetone. The electrospun PVDF membranes were viewed under a scanning electron microscope. Effects of acetone amount, polymer concentration, and capillary-collector distance on the morphology of the membranes were studied. It was suggested that uniform fibrous membranes with fiber diameters ranging mainly from 50 nm to 300 nm were formed from a 15% (wt/v) PVDF solutions in 8 : 2 (v/v) DMF/acetone at 5-kV voltage, 0.3-mL/h flow rate, and 10 ϳ 20-cm capillarycollector distance. After about 10 h of electrospinning, fibrous PVDF membranes with thickness of approximate 46 m were obtained. The tensile moduli and the tensile strengths of the electrospun PVDF membranes were 100 ϳ 170 MPa and 4 ϳ 5 MPa, respectively, from the 13% PVDF solution. Analysis of differential scanning calorimeter and wide angle X-ray diffraction showed that the crystallization of PVDF in the electrospun membranes was weakened compared to the casting film and the raw material. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 466 -474, 2005