Despite the extensive developments of flexible capacitive pressure sensors, it is still elusive to simultaneously achieve excellent linearity over a broad pressure range, high sensitivity, and ultrahigh pressure resolution under large pressure preloads. Here, we present a programmable fabrication method for microstructures to integrate an ultrathin ionic layer. The resulting optimized sensor exhibits a sensitivity of 33.7 kPa−1 over a linear range of 1700 kPa, a detection limit of 0.36 Pa, and a pressure resolution of 0.00725% under the pressure of 2000 kPa. Taken together with rapid response/recovery and excellent repeatability, the sensor is applied to subtle pulse detection, interactive robotic hand, and ultrahigh-resolution smart weight scale/chair. The proposed fabrication approaches and design toolkit from this work can also be leveraged to easily tune the pressure sensor performance for varying target applications and open up opportunities to create other iontronic sensors.
Although
flexible humidity sensors are essential for human health
monitoring, it is still challenging to achieve high sensitivity and
easy disposal with simple, low-cost fabrication processes. This study
presents the design and fabrication of highly reliable hand-drawn
interdigital electrodes from pencil-on-paper treated with NaCl solution
for highly sensitive hydration sensors working over a wide range of
relative humidity (RH) levels from 5.6% to 90%. The applications of
the resulting flexible humidity sensor go beyond the monitoring of
respiratory rate and proximity to characterizations of human skin
types and evaluations of skin barrier functions through insensible
sweat measurements. The sensor array can also be integrated with a
diaper to result in smart diapers to alert for an early diaper change.
The design and fabrication strategies presented in this work could
also be leveraged for the development of wearable, self-powered, and
recyclable sensors and actuators in the future.
Monitoring nitrogen utilization e ciency and soil temperature in agricultural systems for timely intervention is essential to monitor crop health, promote sustainable and precision agriculture, and reduce environmental pollution. Therefore, it is of vital signi cance to develop a multi-parameter sensor for effectively and accurately decoupled detection of nitrogen loss and soil temperature, which is yet to be reported. Herein, this work presents a high-performance multi-parameter sensor based on vanadium oxide (VO X )-doped laser-induced graphene (LIG) foam to completely decouple nitrogen oxides (NO X ) and temperature. By exploiting the laser-assisted synthesis, the highly porous 3D VO X -doped LIG foam composite is readily obtained by laser scribing of vanadium sul de (V 5 S 8 )-doped block copolymer and phenolic resin self-assembled lms. Compared with the intrinsic LIG, the heterojunction formed at the LIG/VO X interface provides the sensor with a signi cantly enhanced response to NO X and an ultralow limit of detection (LOD) of 3 ppb at room temperature. Meanwhile, the sensor can accurately detect temperature over a wide linear range of 10-110℃ with a small detection limit of 0.2℃. The encapsulation of the sensor with a soft membrane further allows for temperature sensing without being affected by NO X , presenting an effective strategy to decouple nitrogen loss and soil temperature for accurate soil environmental monitoring. The sensor without encapsulation but operated at elevated temperature removes the in uences of ambient relative humidity and temperature variations for accurate NO X measurements. The capability to simultaneously detect ultra-low NO X concentrations and small temperature changes paves the way for the development of future multimodal electronic devices with decoupled sensing mechanisms for health monitoring and precision agriculture.
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