An ultra-stretchable and highly-sensitive strain sensor was reported, which can monitor pulse, electrocardiograph, breath, finger motions and emotion changes.

Although two-dimensional (2D) layered molybdenum disulfide (MoS2) has widespread electrical applications in catalysis, energy storage, display, and photodetection, very few reports are available to achieve MoS2 for electromechanical sensing. Here, we report a novel solution-processed MoS2 strain sensor by constructing nanojunctions between layered MoS2 nanosheets and high-conductivity silver nanofibers (AgNFs) inside an elastic film. Benefiting from the outstanding lubrication property of layered MoS2 nanosheets, these nanojunctions can be easily separated by strains, giving rise to excellent electromechanical response. The resulting MoS2 strain sensor for the first time exhibits ultrahigh sensitivity with a gauge factor of 3,300 in a large detection range over 10%. The pronounced strain-sensing ability, combined with fast response speed and good operational stability, enables the MoS2 sensor for real-time and skin-on monitorings of various physiological signals such as finger movements, pulse, and breath. Our results may pave the way to extend 2D materials in novel applications such as soft robotics and human–machine interfaces.

The light-matter interplay on a soft substrate is critically important for novel optoelectronic applications such as soft robotics, human-machine interfaces, and wearable devices. Here, we for the first time report a flexible and efficiency-enhanced hybrid optical modulation transistor (h-OMT) in the ultraviolet-infrared spectral range by blending a polymer with silver nanoparticles (AgNPs). The h-OMT device exhibits a unipolar transport and an ultrahigh on-off ratio of ∼4.8 × 10 in a small voltage range of ∼2 V. Using charge modulation reflection spectroscopy, we demonstrate that the h-OMT device shows a broad-spectral response from 400 to 2000 nm and maximum optical modulation of ∼15% at λ = 785 nm, 6-fold higher magnitude than that of the device without AgNPs. Furthermore, the incorporation of AgNPs enhances the extinction ratio by 4-fold magnitude without any complex geometry designs. We find that the performance improvement relies on the AgNP-induced electron trap states and electrochemical dopings in the polymer. Importantly, the device exhibits pronounced mechanical flexibility, and the optical modulation is kept down to a bending radius of 0.5 mm. Our data provide the possibility of organic materials for constructing novel optoelectronic systems in the future.