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The conflict between high sensitivity and wide sensing range greatly limits the extensive application of flexible pressure sensors. To produce a sensor with both high sensitivity and wide range is still a challenging work. Herein, flexible and highly sensitive piezoresistive sensors with wide sensing range are developed by combining the alkali‐treated 3D crinkled MXene with microstructured polydimethylsiloxane (PDMS). Sensors with different‐roughness PDMS films as flexible substrate and the unprocessed MXene as the conductive material are prepared to clarify the geometric design for the ultra‐wide pressure range (0–800 kPa). Then, other sensors assembled by NaOH‐alkalized 3D crinkled MXenes and rough PDMS are fabricated to illustrate that the material optimization can further enhance the sensitivity (up to 1104.38 kPa−1). The sensor shows a low limit of detection (17 Pa), fast response time (100 ms), good cycle stability (3000 cycles, 300 kPa), and can detect over a wide pressure range from that of the tiny pills, pulse, heartbeat, throat vibration, and the change of water weight, exhibiting a broad prospect in health monitoring systems and human‐machine interaction.

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Reducing the filling content of high-density ferromagnetic particles is a key prerequisite for obtaining lightweight absorbers. To this end, large iron nanowires (Fe NWs) with high length-diameters, uniform length of approximately 21 µm and diameters of approximately 60 nm were synthesized through a facile magnetic field-induced in situ reduction method without templates and surfactants. The phase structures, and micromorphology of the high-aspect-ratio Fe NWs were analyzed, and the electromagnetic properties of Fe NWs-paraffin composites were measured with a vector network analyzer at 2-18 GHz. The Fe NWs-paraffin composite with a low filler loading also exhibited satisfactory microwave absorption performance, and the composites filled with 20 wt.% of as-prepared Fe NWs shows a minimum reflection loss (RL min ) of −44.67 dB at 2.72 GHz and effective absorption bandwidth (EAB) with reflection loss below −10 dB reached 8.56 GHz at a layer thickness of 1.42 mm. At a thickness of 3 mm, the RL min value and EAB (RL ⩽ −10 dB) reached −29.74 dB and 3.28 , respectively. This study suggests that Fe NWs with high-aspect-ratios have promising microwave absorbing applications, and provides a good reference for the preparation of ferromagnetic metal-based lightweight electromagnetic wave-absorbing materials.

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