Loop-mediated isothermal amplification (LAMP) is a nucleic acid amplification technique that rapidly amplifies specific DNA molecules at high yield. In this study, a microfluidic droplet array chip was designed to execute the digital LAMP process. The novel device was capable of 1) creating emulsion droplets, 2) sorting them into a 30 × 8 droplet array, and 3) executing LAMP across the 240 trapped and separated droplets (with a volume of 0.22 nL) after only 40 min of reaction at 56 °C. Nucleic acids were accurately quantified across a dynamic range of 50 to 2.5 × 10 DNA copies per μL, and the limit of detection was a single DNA molecule. This is the first time that an arrayed emulsion droplet microfluidic device has been used for digital LAMP analysis. When compared to microwell digital nucleic acid amplification assays, this droplet array-based digital LAMP assay eliminates the constraint on the size of the digitized target, which was determined by the dimension of the microwells for its counterparts. Moreover, the capacity for hydrodynamic droplet trapping allows the chip to operate in a one-droplet-to-one-trap manner. This microfluidic chip may therefore become a promising device for digital LAMP-based diagnostics in the near future.

We demonstrate a simple technique for the fabrication of gold nanoparticle single-electron transistors (SET). The technique is based on nanogap fabrication using the nanoparticle break junction technique and dielectrophoretic assembly of thiolated gold nanoparticles into the nanogap. Electron transport measurements at 4.2 K show a clear and periodic Coulomb diamond structure, characteristic of an SET from a single quantum dot. We performed simulations using a commercially available SET Monte Carlo simulator to further verify that the observed transport behavior stems from a single dot and obtained different parameters for the SET.

First-principles calculations were performed to investigate the electronic and magnetic properties of Ti 3 C 2 monolayer and its derivatives. We found that pristine Ti 3 C 2 monolayer acts as a magnetic metal, and magnetic moments come from Ti 2+ ions at two sides. Through doping nitrogen atoms, the spin moments is significantly reduced. On other hand, when two surfaces of Ti 3 C 2 monolayer are saturated by external groups, the magnetism will be spontaneously annihilated. Even for the saturation of one side, we also found that the magnetism of Ti 3 C 2 Y (Y is O and OH) monolayer is removed because of the invalidation of stoner instability. More importantly, we explored that both doping and surface modification will reduce the Curie temperature of Ti 3 C 2 monolayer. Therefore, our results shed a light on the way to get high-temperature magnetism in Ti 3 C 2 monolayer.

We have fabricated single-electron transistors by alkanedithiol molecular self-assembly. The devices consist of spontaneously formed ultrasmall Au nanoparticles linked by alkanedithiols to nanometer-spaced Au electrodes created by electromigration. The devices reproducibly exhibit addition energies of a few hundred meV, which enables the observation of single-electron tunneling at room temperature. At low temperatures, tunneling through discrete energy levels in the Au nanoparticles is observed, which is accompanied by the excitations of molecular vibrations at large bias voltage.

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