Highly sensitive and wide-detection range pressure sensor constructed on a hierarchical-structured conductive fabric as a human-machine interface.

With the booming development of flexible pressure sensors, the need for multifunctional and high-performance pressure sensor has become increasingly important. Although great progress has been made in the novel structure and sensing mechanism of the pressure sensor, the trade-off between the sensitivity and the wide-detection range has prevented its development, further restricting its application in wearable human-machine interfaces (WHMIs). Herein, a novel pressure sensor based on the hierarchical conductive fabric was fabricated and purposed as a WHMI. Poly(3,4-ethylenedioxythiophene) nanowires (PEDOT NWs) and cellulose nanofibers (CNF) were stacked on a conductive poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) fabric to form a special spatial multi-level hierarchical structure inside the fabric, which is a breakthrough for the improvement of the sensor's performance and makes the fabrication process of in situ polymerization suitable for large-scale production. The multi-level hierarchical structures endowed the pressure sensor with characteristics of high sensitivity (15.78 kPa-1), a wide-detection range from 30 Pa to 700 kPa, and outstanding stability toward compression and bending deformation. Benefiting from its excellent performance, a human-machine interface based on arrayed pressure sensors and signal processing system can control the illumination of the LED array and effectively capture finger motion to control the eight-direction movement of an unmanned aerial vehicle (UAV). This improved performance of the pressure sensor based on the hierarchical conductive fabric made it a widespread application in intelligent fabric, electronic skin, human-machine interfaces, and robotics.

pH sensor based on upconverting luminescent lanthanide nanorods.

The pH sensor exploits the phenomenon of upconversion luminescence and is based on a hydrogel matrix containing (a) nanorods of the NaYF(4):Er,Yb type that can be excited with 980-nm laser light to give a green and red (dual) emission, and (b) a longwave absorbing pH probe that causes a pH-dependent inner filter effect.

A study on the near-infrared luminescent properties of xerogel materials doped with dysprosium complexes.

A series of dysprosium complex doped xerogels with the same first ligand (acac = acetylacetone) and different neutral ligands were synthesized in situ via a sol-gel process. The Fourier transform infrared (FTIR) spectra, diffuse reflectance (DR) spectra, and near-infrared (NIR) luminescent properties of dysprosium complexes and dysprosium complex doped xerogels are described in detail. The results reveal that the dysprosium complex is successfully synthesized in situ in the corresponding xerogel. Excitation at the maximum absorption wavelength of the ligands resulted in the characteristic NIR luminescence of the Dy3+ ion, which contributes to the energy transfer from the ligands to the central Dy3+ ion in both the dysprosium complexes and xerogels via an antenna effect. The NIR luminescent properties of the dysprosium complexes and xerogels were compared, respectively. The evidence showed that the neutral ligand triphenyl phosphine oxide (TPPO) could increase the emission intensity of the dysprosium complex while 1,10-phenanthroline (phen) gave the negative effect. In addition, the coordinated water molecules affect the emission intensity of the dysprosium complex doped xerogel without the neutral ligand.

Near-infrared luminescent xerogel materials covalently bonded with ternary lanthanide [Er(III), Nd(III), Yb(III), Sm(III)] complexes.

A beta-diketone ligand 4,4,5,5,5-pentafluoro-1-(2-naphthyl)-1,3-butanedione (Hpfnp), which contains a pentafluoroalkyl chain, was synthesized as the main sensitizer for synthesizing new near-infrared (NIR) luminescent Ln(pfnp)(3)phen (phen = 1,10-phenanthroline) (Ln = Er, Nd, Yb, Sm) complexes. At the same time, a series of lanthanide complexes covalently bonded to xerogels by the ligand 5-(N,N-bis-3-(triethoxysilyl)propyl)ureyl-1,10-phenanthroline (phen-Si) were synthesized in situvia a sol-gel process. [The obtained materials are denoted as xerogel-bonded Ln complexes (Ln = Er, Nd, Yb, Sm).] The single crystal structures of the Ln(pfnp)(3)phen complexes were determined. The properties of these complexes and the corresponding xerogel materials were investigated by Fourier-transform infrared (FTIR), diffuse reflectance (DR), and field-emission scanning electron microscopy (FE-SEM). After ligand-mediated excitation of these complexes and the corresponding xerogel materials they all show the characteristic NIR luminescence of the corresponding Ln(3+) ion. This is attributed to efficient energy transfer from the ligands to the Ln(3+) ion (the so-called "antenna effect").

Near-infrared emission from novel Tris(8-hydroxyquinolinate)lanthanide(III) complexes-functionalized mesoporous SBA-15.

A novel mesoporous material covalently bonded with 8-hydroxyquinoline (HQ) was synthesized (designated as Q-SBA-15). The 5-formyl-8-hydroxyquinoline grafted to (3-aminopropyl)triethoxysilane, that is, alkoxysilane modified 8-hydroxyquinoline (Q-Si), was used as one of the precursors for the preparation of the Q-SBA-15 material. On the basis of the other function of the Q-Si of coordinating to lanthanide (Ln) ions, for the first time, the LnQ 3 complexes (Ln = Er, Nd, Yb) have been covalently bonded to the SBA-15 materials. The derivative materials, denoted as LnQ 3-SBA-15, were characterized by field emission scanning electron microscopy (FE-SEM), powder X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption-desorption, and fluorescence spectra. Upon excitation at the ligands absorption bands, all of these materials show the characteristic near-infrared (NIR) luminescence of the corresponding lanthanide ions through the intramolecular energy transfer from the ligands to the lanthanide ions. The NIR luminescence of these mesoporous materials was compared with that of the corresponding pure LnQ 3 complexes and discussed in detail.

Template-free fabrication of hexagonal ZnO microprism with an interior space.

Well-faceted hexagonal ZnO microprisms with regular interior space have been successfully prepared by a template-free hydrothermal synthetic route. The morphologies of the products depend on the experimental conditions such as the solvent, the concentration of ammonia aqueous solution, and the reaction temperature. Through manipulation of the aging time, the as-prepared ZnO can be controlled as a monodispersed hexagonal twinning solid or as hollow microprisms. Moreover, the evolution process of the hollow ZnO nanoarchitecture after reaction for 2, 6, 12, and 24 h has been investigated by field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). A possible growth mechanism has also been proposed and discussed. Furthermore, the photoluminescence (PL) measurement exhibits the unique emitting characteristic of hollow ZnO nanostructures.

Bifunctional magnetic-optical nanocomposites: grafting lanthanide complex onto core-shell magnetic silica nanoarchitecture.

A new class of bifunctional architecture combining the useful functions of superparamagnetism and terbium complex luminescence into one material has been prepared via two main steps by a modified Stöber method and the layer-by-layer (LbL) assembly technique. The obtained bifunctional nanocomposites exhibit superparamagnetic behavior, high fluorescence intensity, and color purity. The architecture has been characterized by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), UV-vis absorption and emission spectroscopy, X-ray diffraction, and superconducting quantum interference device (SQUID) magnetometry.

Covalent linking of near-infrared luminescent ternary lanthanide (Er(3+), Nd(3+), Yb(3+)) complexes on functionalized mesoporous MCM-41 and SBA-15.

The near-infrared (NIR) luminescent lanthanide ions, such as Er(III), Nd(III), and Yb(III), have been paid much attention for the potential use in the optical communications or laser systems. For the first time, the NIR-luminescent Ln(dbm)(3)phen complexes have been covalently bonded to the ordered mesoporous materials MCM-41 and SBA-15 via a functionalized phen group phen-Si (phen-Si = 5-(N,N-bis-3-(triethoxysilyl)propyl)ureyl-1,10-phenanthroline; dbm = dibenzoylmethanate; Ln = Er, Nd, Yb). The synthesis parameters X = 12 and Y = 6 h (X denotes Ln(dbm)(3)(H(2)O)(2)/phen-MCM-41 molar ratio or Ln(dbm)(3)(H(2)O)(2)/phen-SBA-15 molar ratio and Y is the reaction time for the ligand exchange reaction; phen-MCM-41 and phen-SBA-15 are phen-functionalized MCM-41 and SBA-15 mesoporous materials, respectively) were selected through a systematic and comparative study. The derivative materials, denoted as Ln(dbm)(3)phen-MCM-41 and Ln(dbm)(3)phen-SBA-15 (Ln = Er, Nd, Yb), were characterized by powder X-ray diffraction, nitrogen adsorption/desorption, Fourier transform infrared (FT-IR), elemental analysis, and fluorescence spectra. Upon excitation of the ligands absorption bands, all these materials show the characteristic NIR luminescence of the corresponding lanthanide ions through the intramolecular energy transfer from the ligands to the lanthanide ions. The excellent NIR-luminescent properties enable these mesoporous materials to have potential uses in optical amplifiers (operating at 1.3 or 1.5 mum), laser systems, or medical diagnostics. In addition, the Ln(dbm)(3)phen-SBA-15 materials show an overall increase in relative luminescent intensity and lifetime compared to the Ln(dbm)(3)phen-MCM-41 materials, which was explained by the comparison of the lanthanide ion content and the pore structures of the two kinds of mesoporous materials in detail.

Near-infrared luminescent hybrid materials doped with lanthanide (Ln) complexes (Ln = Nd, Yb) and their possible laser application.

The crystal structures of ternary Ln(DBM)(3)phen complexes (DBM = dibenzoylmethane, phen = 1,10-phenanthroline, and Ln = Nd, Yb) and their in situ syntheses via the sol-gel process are reported. The properties of the Ln(DBM)(3)phen complexes and their corresponding Ln(3+)/DBM/phen-co-doped luminescent hybrid gels obtained via an in situ method (Ln-D-P gel) have been studied. The results reveal that the lanthanide complexes are successfully in situ synthesized in the corresponding Ln-D-P gels. Both Ln(DBM)(3)phen complexes and Ln-D-P gels display sensitized near-infrared (NIR) luminescence upon excitation at the maximum absorption of the ligands, which contributes to the efficient energy transfer from the ligands to the Ln(3+) ions (Ln = Nd, Yb), an antenna effect. The radiative properties of the Nd(3+) ion in a Nd-D-P gel are discussed using Judd-Ofelt analysis, which indicates that the (4)F(3/2) --> (4)I(11/2) transition of the Nd(3+) ion in the Nd-D-P gel can be considered as a possible laser transition.