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.

A novel charge-reversible surfactant, (CH 3 ) 2 N-(CH 2 ) 10 COONa, was designed and synthesized, which together with silica nanoparticles can stabilize a smart n-octane-inwater emulsion responsive to pH. At high pH (9.3) the surfactant is anionic carboxylate, which together with the negatively charged silica nanoparticles co-stabilize flowable oil-in-dispersion emulsions, whereas at low pH (4.1) it is turned to cationic form by forming amine salt which can hydrophobize in situ the negatively charged silica nanoparticles to stabilize viscous oil-in-water (O/W) Pickering emulsions. At neutral pH (7.5), however, this surfactant is converted to zwitterionic form, which only weakly hydrophobises the silica particles to stabilize O/W Pickering emulsions of large droplet size. Moreover, demulsification can be achieved rapidly triggered by pH. With this strategy particles can be controlled either dispersed in water or adsorbed at the oil-water interface endowing emulsions with the capacity for intelligent and precise control of stability as well as viscosity and droplet size. Scheme 1. Chemical structure of 11-(N,N-dimethylamino) sodium undecanoate (DMUa, left) and charge variation with pH.

The transition between a novel oil-in-dispersion emulsion and an oil-in-water (O/W) Pickering emulsion triggered by pH was achieved using alumina nanoparticles in combination with a cationic surfactant. In acidic and neutral aqueous media, positively charged particles and the surfactant both at very low concentrations costabilize an oil-in-dispersion emulsion with the surfactant adsorbed at droplet interfaces and particles dispersed in the aqueous phase between the droplets. In alkaline media, however, particles become negatively charged and are hydrophobized in situ by adsorption of the surfactant to become surface-active and stabilize an O/W Pickering emulsion. The transition between the two is also possible by lowering the pH. The transformation can be achieved several times in a mixture of 0.1 wt % nanoparticles and 0.01 mM surfactant. This transition is significant, since particles can be made to either adsorb at the oil–water interface, which is beneficial for applications like biphasic catalysis, or remain dispersed in the aqueous phase, which is favorable for their recovery and reuse.

Stable n-decane-in-water Pickering emulsions were prepared using positively charged alumina nanoparticles in combination with a trace amount of the anionic surfactant sodium dodecyl sulfate (SDS) as a stabilizer. Particles were hydrophobized in situ by adsorption of surfactant enhancing their surface activity. Emulsions can be readily demulsified by addition of an equal amount of a switchable surfactant,, which can be transformed between a surface-active amidinium/cationic form and a surface-inactive amidine/neutral form by bubbling CO 2 or N 2 ,respectively. Following addition of cationic DDAA which prefers to form ion pairs with SDS, desorption of SDS from particle surfaces occurs and alumina particles are rendered hydrophilic resulting in demulsification of the emulsion. However, by bubbling N 2 into the demulsified mixture, DDAA molecules are converted to the amidine/neutral form leading to collapse of the ion pairs and re-establishment of the in situ hydrophobization of particles. Stable Pickering emulsions can be prepared again following homogenization. This simple demulsification/re-stabilization cycle can be repeated several times.Experimental evidence including measurement of the adsorption isotherm, zeta potentials, extent of particle adsorption at droplet interfaces in emulsions and microscopy is given to support the postulated mechanisms.

Parkinson's disease (PD) is pathologically characterized by selective loss of dopaminergic neurons in the midbrain and the existence of intracellular protein inclusions termed Lewy bodies, largely composed of α-synuclein. Genetic studies have revealed that rare point mutations in the gene encoding α-synuclein including A30P, A53T, and E46K are associated with familial forms of PD, indicating a pathological role for mutant α-synuclein in PD etiology. However, the mechanisms underlying the neuronal toxicity of mutant α-synuclein are still to be elucidated. Growing evidence has suggested a deleterious effect of mutant α-synuclein on the autophagy-lysosome pathway. In this study, we discovered that overexpression of human E46K mutant α-synuclein impaired macroautophagy in mammalian cells. Our data showed that overexpression of E46K mutant α-synuclein impaired autophagy at an early stage of autophagosome formation via the c-Jun N-terminal kinase 1 (JNK1)-Bcl-2 but not the mammalian target of rapamycin (mTOR) pathway. Overexpressed E46K mutant α-synuclein inhibited JNK1 activation, leading to a reduced Bcl-2 phosphorylation and increased association between Bcl-2 and Beclin1, further disrupting the formation of Beclin1/hVps34 complex, which is essential for autophagy initiation. Furthermore, overexpression of E46K mutant α-synuclein increased the vulnerability of differentiated PC12 cells to rotenone treatment, which would be partly due to its inhibitory effects on autophagy. Our findings may shed light on the potential roles of mutant α-synuclein in the pathogenesis of PD.

Health monitoring of structures and people requires the integration of sensors and devices on various 3D curvilinear, hierarchically structured, and even dynamically changing surfaces. Therefore, it is highly desirable to explore conformal manufacturing techniques to fabricate and integrate soft deformable devices on complex 3D curvilinear surfaces. Although planar fabrication methods are not directly suitable to manufacture conformal devices on 3D curvilinear surfaces, they can be combined with stretchable structures and the use of transfer printing or assembly methods to enable the device integration on 3D surfaces. Combined with functional nanomaterials, various direct printing and writing methods have also been developed to fabricate conformal electronics on curved surfaces with intimate contact even over a large area. After a brief summary of the recent advancement of the recent conformal manufacturing techniques, we also discuss the challenges and potential opportunities for future development in this burgeoning field of conformal electronics on complex 3D surfaces.

Newly structured pH‐responsive smart surfactants (N+‐(n)‐N, n=14, 16) from alkyl trimethylammonium bromides are reported. In neutral and alkaline media N+‐(n)‐N behaves as a normal cationic surfactant and stabilizes conventional emulsions alone, as well as Pickering emulsions and oil‐in‐dispersion emulsions together with oppositely and similarly charged nanoparticles, respectively. In acidic media N+‐(n)‐N becomes a hydrophilic Bola‐type surfactant, N+‐(n)‐NH+, and is an inferior emulsifier either when used alone or together with charged nanoparticles, resulting in demulsification. N+‐(n)‐NH+ returns to the aqueous phase alone or together with nanoparticles after demulsification without contaminating the oil phase, and the aqueous phase can be recycled when triggered by pH change. This protocol is a green process and leads to preparation of various temporarily stable emulsions which are often used in emulsion polymerization, heterogeneous catalysis, and oil transportation.

Newly structured pH‐responsive smart surfactants (N+‐(n)‐N, n=14, 16) from alkyl trimethylammonium bromides are reported. In neutral and alkaline media N+‐(n)‐N behaves as a normal cationic surfactant and stabilizes conventional emulsions alone, as well as Pickering emulsions and oil‐in‐dispersion emulsions together with oppositely and similarly charged nanoparticles, respectively. In acidic media N+‐(n)‐N becomes a hydrophilic Bola‐type surfactant, N+‐(n)‐NH+, and is an inferior emulsifier either when used alone or together with charged nanoparticles, resulting in demulsification. N+‐(n)‐NH+ returns to the aqueous phase alone or together with nanoparticles after demulsification without contaminating the oil phase, and the aqueous phase can be recycled when triggered by pH change. This protocol is a green process and leads to preparation of various temporarily stable emulsions which are often used in emulsion polymerization, heterogeneous catalysis, and oil transportation.