Yang Liu

This work numerically reveals a novel strategy to modulate two ionic conductance state in a nanochannel via pressure-dependent fluidic motion inside the channel. Steady and transient simulations based on Poisson–Nernst–Planck–Stokes equations demonstrate that the two states with distinct ionic conductance and ion selectivity can be reversibly switched by external pressure, with a characteristic time of ~100 μs. Furthermore, the two conductance states are found to depend on the transversal electric field, which gives rise to two distinct intrachannel fluidic flow patterns, namely laminar flow and vortex flow, respectively. This finding suggests the potential of pressure-controlled ionic conductance switching for applications in nanofluidic ionic circuits, flow-regulated sensing, and integrated micro/nanoscale devices. It also provides insights into nonlinear ionic current–voltage behaviors.

Solid-state nanopores hold substantial potential in single-molecule sensing. Fully wetting the nanopore is a crucial but challenging pre-treatment step for biomolecule sensing. Conventional wetting techniques, including passive wetting, plasma treatment, mechanical pressure, and thermal treatment, and chemical treatment, often suffer from limited effectiveness, high complexity, or incompatibility with certain materials and nanopore geometries. This work proposes a contactless ultrasonic wave-facilitated wetting (UFW) method for rapid nanopore wetting. Our experimental findings demonstrate that UFW enhances the wetting speed by over three orders of magnitude in SiNx nanopores compared to passive wetting, reducing the wetting time to minutes. Improvements are also observed in sandwiched ZnO–SiNx and ITO–SiNx structure nanopores with varying hydrophilicity. This work provides a rapid, real-time, chemical-free, and low-cost wetting method for solid-state nanopores and may also be applicable to other nanostructured systems.

Based on the bulk-Si substrate, the CMOS tree-like FETs including the FishboneFETs with bottom SiGe nano-fin and the TreeFETs without bottom SiGe nano-fin were both designed and experimentally fabricated. The growth of bottom SiGe layer with different Ge fraction following by an accurately selective etching is developed for realizing SiGe nano-fins between Si nanosheets (NSs). The results show that the I _on / I _off ratio (over 1×10 ⁵ ) and the short channel effects (SCEs) of TreeFETs are effectively optimized, and the effective channel width ( W _eff is increased for FishboneFETs on the same footprint. Due to the hole conduction advantage of SiGe nano-fin, the on-current ( I _on ) of p-type TreeFETs can be higher than that of n-type TreeFETs at V _OV =| V _gs - V _th |=0.5 V. Meanwhile, the surface scattering of SiGe nano-fin also affects the effective field-effect mobility. As the L _g scaling, both p-type tree-like FETs exhibit more obvious SCEs than n-type devices, which is maybe the reason of a lower hole barrier occurring by the valence band offset (Δ E _v ) obtained in the strained SiGe nano-fin. The results provided one meaningful guide for tree-like FETs optimizing future GAAFET process and CMOS circuits.

MoS ₂ -graphene heterostructure nanopores can prolong the dwell time of BSA molecules up to more than 100 ms compared with other kinds of nanopores.

Nanopores that integrate indium-tin-oxide (ITO) electrical gates have previously demonstrated the capability of modulating the DNA folding/knotting configurations in their translocation dwell times in such devices. Four ITO-SiNx nanopore devices are fabricated with their sizes in the 8 ∼ 20 nm range. The current blockage and dwell time characterizations using these nanopores are presented for DNAs entering from both the SiNx and ITO sides of the nanopores with 0 V bias applied at the ITO gate. While the current blockage data show little dependence on nanopore sizes, dwell time appears to be shorter with smaller nanopore sizes. Interestingly, the dwell times of DNAs entering from the ITO side are observed to be shorter than those of the reverse direction, suggesting the DNA translocation process is affected by the asymmetry of the layered nanopore structures. This work proves ITO as a compatible material for DNA translocation and provides a basic research for the velocity studies of DNA translocation in gated nanopores.

We propose and fabricate solid-state nanopore devices that monolithically integrate solution-gated, vertical thin-film transistors (TFTs) inside the nanopores for charge-based sensing of translocating biomolecules. The TFTs consist of zinc oxide semiconductor channels and aluminum oxide gate dielectrics, which are both conformally deposited along the inner surfaces of the nanopores via atomic layer deposition. The resultant TFT channel lengths and nanopore diameters both reach the ∼10 nm range. In translocation experiments using λ-DNAs or bovine serum antibody (BSA) proteins, the TFT–nanopore devices demonstrate concurrent detection of the ion conductance blockade signals and modulation signals in the TFT electrical current. The TFT signals show opposite signs for the negatively charged DNAs and positively charged BSAs as well as staircase signal shapes that correspond to the folding and knotting of λ-DNAs. Further experiments under various electrical biases and solution ionic strengths show that the ion blockade signals and the TFT signals have different dependence upon these experimental conditions. The TFT signals are analyzed to be consistent with the field effect sensing of the biomolecular charge, and the induced mirror charge is estimated from the signal amplitudes. This study could be a step forward to achieve charge-based single-biomolecular technology for basic research as well as for biosensing applications. It may also stimulate the development of TFT technologies for conformal integration of semiconductor electronics at the front end of nanostructures.

Three types of highly transparent inverter circuits, enhancement/depletion, pseudo-CMOS and feedback structures, are fabricated by using zinc-oxide thin film transistors (TFTs) with deuterium plasma immersion to adjust the threshold voltage of the depletion-mode TFTs. Their DC and AC performance are investigated and compared systematically. Especially, the feedback structure inverters demonstrate a maximum gain of −310V/V at VDD = 10 V, which is the highest DC gain ever to be reported for oxide TFTs. Furthermore, the frequency responses of these three inverter types are examined, showing a maximum AC gain of 210 V/V at a 10 mV amplitude input in the pseudo-CMOS inverters. These high-gain transparent inverters have great potential to be used as the common-source amplifiers in the measurement of photo-stimulated electroencephalogram signals.

This experimental work studies the translocation of bovine serum albumin (BSA) proteins through MoS₂ nanopores. A simple method of device fabrication is developed based on dry-transfer of exfoliated MoS₂ membranes and subsequent TEM drilling, yielding MoS₂ nanopores of a few monolayers thick and diameters as small as ∼11 nm. The current-voltage relation and low-frequency current noise of the devices are characterized. Typical BSA translocation signals that possibly correspond to various orientations are observed in the MoS₂ devices, exhibiting enhanced amplitude and similar characteristics when compared to those from a silicon nitride (SiN_x) control. Furthermore, the statistical data of the signal amplitude and dwell time at various biases are analyzed. These results show opportunities of single-molecular protein analysis using MoS₂ nanopores.