Three-dimensional (3D) porous conductive composites explored in highly sensitive tactile sensors have attracted extensive close attention in recent years owing to their peculiar porous structure and unique physical properties in terms of excellent mechanical flexibility, high relative dielectric permittivity, and good elastic property. Herein, we report an practical, efficient, and macroscopic dip-coating process to manufacture rapid-response, low detection limit, high-sensitivity, and highly sensitive capacitive flexible tactile sensors. The fabrication process, tactile perception mechanism, and sensing performance of the developed devices are comparatively investigated. The homogeneous 3D hybrid network constructed by graphene nanoplatelets/carboxyl-functionalized multiwalled carbon nanotubes/silicone rubber composites anchored on polyurethane sponge skeletons exhibits a significantly improved dielectric property, resulting in a high-performance capacitive flexible tactile sensor with a fast response time (∼45 ms), an extremely low-pressure detection limit of ∼3 Pa, excellent sensitivity (∼0.062 kPa–1), and excellent durability and stability over 2000 cycles. Importantly, the flexible devices can be used as the wearable electronic skin and successfully mounted on human skin or a soft-bodied robot to achieve the capability of physiological stimuli monitoring, micropressure monitoring, soft grabbing, etc. Our rapid-response, low detection limit, and high-sensitivity capacitive flexible tactile sensor with a novel 3D porous dielectric layer could be a prospective candidate for the wearable applications in real-time and high-accuracy portable healthcare monitoring devices, advanced human–machine interfaces, and intelligent robot perception systems.

Two ground radiation antennas with polarisation diversity performance were proposed for MIMO WLAN applications in wearable devices. The antennas can simultaneously excite the vertical mode and horizontal mode of the ground plane and the phase difference between the two modes can be controlled by utilising an inductor‐loaded metal strip in the ground plane, generating circular polarisation. A 3:1 VSWR bandwidth of 140 MHz with high isolation (above 17 dB) and a 3 dB axial ratio bandwidth of 100 MHz was obtained. The opposite rotations generated by the two antennas resulted in good diversity performance, which was verified by the measured envelope correlation coefficient.

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A compact and easy to fabricate decoupling method is proposed to yield high isolation for the multiple‐input and multiple‐output (MIMO) ground radiation antenna (GradiAnt) system. The proposed MIMO antenna system is comprised of two symmetrical, closely spaced, loop‐type (GradiAnts) with a ground‐coupled loop‐type isolator inserted between them. The isolator can be seen as a series resonant circuit which is connected with lumped components to control decoupling. In the proposed MIMO GradiAnt system, a coupling null is induced due to the ground‐coupled isolator, which effectively can be used for isolation enhancement between two GradiAnts. Within WLAN band, a minimum 14 dB isolation with a peak value of 42 dB at 2.42 GHz is achieved. In this manuscript, the decoupling principle and controlling mechanisms are first explained, then the antenna performances and tuning mechanisms are discussed in detail. The simulation and the measurement of the MIMO antenna, including the scattering parameters, efficiency, radiation patterns, peak gains and envelope correlation coefficients are conducted to verify the performance of the proposed MIMO system.