RESUMEN
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.
RESUMEN
Deployment of functional circuits on a 3D freeform surface is of significant interest to wearable devices on curvilinear skin/tissue surfaces or smart Internet-of-Things with sensors on 3D objects. Here we present a new fabrication strategy that can directly print functional circuits either transient or long-lasting onto freeform surfaces by intense pulsed light-induced mass transfer of zinc nanoparticles (Zn NPs). The intense pulsed light can locally raise the temperature of Zn NPs to cause evaporation. Lamination of a kirigami-patterned soft semi-transparent polymer film with Zn NPs conforming to a 3D surface results in condensation of Zn NPs to form conductive yet degradable Zn patterns onto a 3D freeform surface for constructing transient electronics. Immersing the Zn patterns into a copper sulfate or silver nitrate solution can further convert the transient device to a long-lasting device with copper or silver. Functional circuits with integrated sensors and a wireless communication component on 3D glass beakers and seashells with complex surface geometries demonstrate the viability of this manufacturing strategy.
RESUMEN
The recent advent of stretchable gas sensors demonstrates their capabilities to detect not only gaseous biomarkers from the human body but also toxic gas species from the exposed environment. To ensure accurate gas detection without device breakdown from the mechanical deformations, the stretchable gas sensors often rely on the direct integration of gas-sensitive nanomaterials on the stretchable substrate or fibrous network, as well as being configured into stretchable structures. The nanomaterials in the forms of nanoparticles, nanowires, or thin-films with nanometer thickness are explored for a variety of sensing materials. The commonly used stretchable structures in the stretchable gas sensors include wrinkled structures from a pre-strain strategy, island-bridge layouts or serpentine interconnects, strain isolation approaches, and their combinations. This review aims to summarize the recent advancement in novel nanomaterials, sensor design innovations, and new fabrication approaches of stretchable gas sensors.