Highly sensitive and multimodal sensors have recently emerged for a wide range of applications, including epidermal electronics, robotics, health‐monitoring devices and human–machine interfaces. However, cross‐sensitivity prevents accurate measurements of the target input signals when a multiple of them are simultaneously present. Therefore, the selection of the multifunctional materials and the design of the sensor structures play a significant role in multimodal sensors with decoupled sensing mechanisms. Hence, this review article introduces varying methods to decouple different input signals for realizing truly multimodal sensors. Early efforts explore different outputs to distinguish the corresponding input signals applied to the sensor in sequence. Next, this study discusses the methods for the suppression of the interference, signal correction, and various decoupling strategies based on different outputs to simultaneously detect multiple inputs. The recent insights into the materials' properties, structure effects, and sensing mechanisms in recognition of different input signals are highlighted. The presence of the various decoupling methods also helps avoid the use of complicated signal processing steps and allows multimodal sensors with high accuracy for applications in bioelectronics, robotics, and human–machine interfaces. Finally, current challenges and potential opportunities are discussed in order to motivate future technological breakthroughs.

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.

Label-free, size-dependent, and high-throughput isolation of rare tumor cells from untreated whole blood is enabled by interfacial viscoelastic microfluidics.

The microfluidic passive control of microparticles largely relies on the hydrodynamic effects of the carrier media such as Newtonian fluids and viscoelastic fluids. Yet the viscoelastic/Newtonian interfacial effect has been scarcely investigated, especially for high-resolution particle separation. Here we report a microfluidic co-flow of Newtonian (water or PBS) and viscoelastic fluids (PEO) for the size-dependent separation of microparticles. The co-flow condition generates a stable viscoelastic/Newtonian interface, giving rise to the wall-directed elastic lift forces that compete with the center-directed lift forces, and efficiently hinders the migration of microparticles from the Newtonian to the viscoelastic fluid in a size-dependent manner. An almost complete separation of a binary mixture of 1 μm and 2 μm polystyrene particles is achieved by the co-flow of water and a very dilute PEO solution (100 ppm), whereas the sole use of water or PEO could not lead to an efficient separation. This co-flow microfluidic system is also applied for the separation of Staphylococcus aureus (1 μm) from platelets (2–3 μm) with >90% efficiencies and purities.