chenyu wen - Academia.edu (original) (raw)

Papers by chenyu wen

Journal of Biosensors and Bioelectronics, 2018

Single molecule detection is of vital importance for fundamental biotechnology research and pract... more Single molecule detection is of vital importance for fundamental biotechnology research and practical applications. Among the numerous single molecule detection techniques, solid-state nanopores have been developed as single molecule sensors for the investigation of unlabeled biopolymers such as DNA, RNA and protein owing to their robustness, pore size controllability and tunability of physical/chemical properties. The most commonly used method today to form ultra-small nanopores relies on using focused high energy electron beams on a transmission electron microscope (TEM). However, the sophisticated operation of TEM, high cost and low throughput limit its extensive applications. In this work, we start with electron beam lithography combined with reactive ion etching to massively prefabricate nanopores with relatively large size in free-standing silicon nitride membranes. Then, electron beam irradiation is used to deposit carbon with a conventional scanning electron microscope so as to reduce the size of prefabricated pores. This process leads to the controllable formation of solid-state carbon nanopores sub-30 nm in diameter. We subsequently use the carbon nanopores to study translocation of λ-DNA as a demonstration of the capability of such carbon nanopores. By tuning bias voltage, the translocation events show regular changes in amplitude, dwell time and appearance frequency. With this advanced nanopore platform, detection of single DNA molecules is achieved with a high signal-to-noise ratio of ~6

The model of diffusive O2 transport from capillary to tissue was established by Krogh a century a... more The model of diffusive O2 transport from capillary to tissue was established by Krogh a century ago. This model is incomplete as it ignores the often inevitable convective O2 transport via fluid movement. Here, we propose a one-dimensional physical-phenomenological model to evaluate the contribution of fluid movement to the O2 transport in tissue. Both the O2 gradient and the total O2 flux are found to be sensitive to the fluid movement. For small flow rates with a Peclet number Pe < 1, a critical flow rate, udc, is introduced to characterize the contribution of fluid movement to the O2 transport, as well as to evaluate the fluid contribution in O2-deficient tissues and the cytoplasm movement inside muscle fibers. During hemostasis, the O2 flux contributed by the interstitial flow even below a rate of 2 μm/s, although negligible near the capillary, can be significant for the tissue residing far from the capillary. For an isolated intramyocyte mitochondrion, the cytoplasm movement...

Solid-state nanopores (SSNPs) of on-demand shape and size can facilitate desired sensor performan... more Solid-state nanopores (SSNPs) of on-demand shape and size can facilitate desired sensor performance. However, reproducible production of arrayed nanopores of predefined geometry is yet to demonstrate despite of numerous methods explored. Here, bowl-shape SSNPs combining unique properties of ultrathin membrane and tapering geometry are demonstrated. The bowl-SSNP upper opening is 100-120 nm in diameter, with the bottom opening reaching sub-5 nm. Numerical simulation reveals the formation of multiple electroosmotic vortexes (EOVs) originating from distributed surface charge around the pore-bowl. The EOVs determine, collaboratively with electrophoretic force, how nanoscale objects translocate the bowl-SSNPs. Exceptional rectification with higher frequencies, longer duration and larger amplitude is found when DNA strands translocate downwards from the upper large opening than upwards from the bottom smallest restriction. The rectification is a manifestation of the interplay between elec...

Nano Energy, 2021

The tactile peripheral nervous system innervating human hands, which is essential for sensitive h... more The tactile peripheral nervous system innervating human hands, which is essential for sensitive haptic exploration and dexterous object manipulation, features overlapped receptive fields in the skin, arborization of peripheral neurons and many-to-many synaptic connections. Inspired by the structural features of the natural system, we report a supersensitive artificial slowly adapting tactile afferent nervous system based on the triboelectric nanogenerator technology. Using tribotronic transistors in the design of mechanoreceptors, the artificial afferent nervous system exhibits the typical adapting behaviours of the biological counterpart in response to mechanical stimulations. The artificial afferent nervous system is self-powered in the transduction and event-driven in the operation. Moreover, it has inherent proficiency of neuromorphic signal processing, delivering a minimum resolvable dimension two times smaller than the inter-receptor distance which is the lower limit of the dimension that existing electronic skins can resolve. These results open up a route to scalable neuromorphic skins aiming at the level of human's exceptional perception for neurorobotic and neuroprosthetic applications.

IEEE Electron Device Letters, 2020

Hysteresis is a frequently observed phenomenon in the transfer characteristics of thin film trans... more Hysteresis is a frequently observed phenomenon in the transfer characteristics of thin film transistors. Charge trapping/de-trapping processes of gate oxide and gate-channel interface are commonly known to be the origin of hysteresis and correlated to low frequency noise (LFN) properties of the devices. In this letter, a rapid four-point sweeping method (RFSM) is proposed to reveal the dependence of hysteresis, as well as the distribution of effective trap density on sweeping rate and gate bias range. Based on the RFSM, the hysteresis properties of four-layer MoS2 FETs are studied in detail. The experimental results demonstrate that the hysteresis and trap density at different frequencies and gate voltages, which could further roughly map the traps with different time constants and energy depths, can be obtained by the simple RFSM. Trap density estimated by RFSM shows a comparable range with that extracted from LFN, indicating that the traps inducing the hysteresis may also cause LFN.

Interfacing solid-state nanopores with biological systems has been exploited as a versatile analy... more Interfacing solid-state nanopores with biological systems has been exploited as a versatile analytical platform for analysis of individual biomolecules. Although clogging of solid-state nanopores due to nonspecific interactions between analytes and pore walls poses a persistent challenge in attaining the anticipated sensing efficacy, insufficient studies focus on elucidating the clogging dynamics. Herein, we investigate the DNA clogging behavior by passing double-stranded (ds) DNA molecules of different lengths through hafnium oxide(HfO 2)-coated silicon (Si) nanopore arrays, at different bias voltages and electrolyte pH values. Employing stable and photoluminescent-free HfO 2 /Si nanopore arrays permits a parallelized visualization of DNA clogging with confocal fluorescence microscopy. We find that the probability of pore clogging increases with both DNA length and bias voltage. Two types of clogging are discerned: persistent and temporary. In the time-resolved analysis, temporary clogging events exhibit a shorter lifetime at higher bias voltage. Furthermore, we show that the surface charge density has a prominent effect on the clogging probability because of electrostatic attraction between the dsDNA and the HfO 2 pore walls. An analytical model based on examining the energy landscape along the DNA translocation trajectory is developed to qualitatively evaluate the DNA−pore interaction. Both experimental and theoretical results indicate that the occurrence of clogging is strongly dependent on the configuration of translocating DNA molecules and the electrostatic interaction between DNA and charged pore surface. These findings provide a detailed account of the DNA clogging phenomenon and are of practical interest for DNA sensing based on solid-state nanopores.

Analytical Chemistry, 2019

This supporting information includes part of materials and methods section, the results of polyac... more This supporting information includes part of materials and methods section, the results of polyacrylamide gel electrophoresis (PAGE) and Quartz crystal microbalance (QCM) for aptamer-P1 hybridization. Moreover, supplementary EIS results as mentioned in the results and discussions section in the manuscript are also provided in this file.

IEEE Electron Device Letters, 2019

2015 IEEE 11th International Conference on ASIC (ASICON), 2015

Humidity sensors have attracted extensive attentions due to their various applications in environ... more Humidity sensors have attracted extensive attentions due to their various applications in environment monitoring, health care and internet of things. Graphene oxide has recently been exploited as a humidity sensing material because of its good hydrophilicity and excellent sensitivity. Here we report an ultra-sensitive and responsive capacitive humidity sensor using graphene oxide as sensing material. A capacitance change of ten times is observed when the relative humidity changes from 50% to 90%. The response and recovery time of the sensor are measured to be 0.066 and 0.154 s, respectively, which are several orders of magnitude shorter than conventional humidity sensors. Furthermore, its responses to flow rate, temperature and other vapors are also characterized.

Scientific reports, Jan 18, 2016

In the field of electronic gas sensing, low-dimensional semiconductors such as single-walled carb... more In the field of electronic gas sensing, low-dimensional semiconductors such as single-walled carbon nanotubes (SWCNTs) can offer high detection sensitivity owing to their unprecedentedly large surface-to-volume ratio. The sensitivity and responsivity can further improve by increasing their areal density. Here, an accelerated gas adsorption is demonstrated by exploiting volumetric effects via dispersion of SWCNTs into a percolating three-dimensional (3D) network in a semiconducting polymer. The resultant semiconducting composite film is evaluated as a sensing membrane in field effect transistor (FET) sensors. In order to attain reproducible characteristics of the FET sensors, a pulsed-gate-bias measurement technique is adopted to eliminate current hysteresis and drift of sensing baseline. The rate of gas adsorption follows the Langmuir-type isotherm as a function of gas concentration and scales with film thickness. This rate is up to 5 times higher in the composite than only with an ...

Nano Energy, 2014

In this paper, a flexible nanogenerator based on direct piezoelectric effect using a spin-coated ... more In this paper, a flexible nanogenerator based on direct piezoelectric effect using a spin-coated poly(vinylidenefluoride-co-trifluoroethylene) (PVDF-TrFE) thin film as functional layer has been fabricated on polyimide substrate. The as-prepared nanogenerator exhibits the open-circuit voltage up to 7 V and short-circuit current of 58 nA with current density of 0.56 μA/cm 2. The impact of the variation of strain rate on the electrical outputs of the nanogenerator has been characterized experimentally and analyzed theoretically. An analytical model that explains well the experimental results has been established.

Analytical Chemistry, 2019

Langmuir, 2020

Solid-state nanopores provide a highly versatile platform for rapid electrical detection and anal... more Solid-state nanopores provide a highly versatile platform for rapid electrical detection and analysis of single molecules. Lipid bilayer coating of the nanopores can reduce non-specific analyte adsorption to the nanopore sidewalls and increase the sensing selectivity by providing possibilities for tethering specific ligands in a cell-membrane mimicking environment. However, mechanism and kinetics of lipid bilayer formation from vesicles remain unclear in the presence of nanopores. In this work, we used a silicon-based, truncated-pyramidal nanopore array as the support for lipid bilayer formation. Lipid bilayer formation in the nanopores was monitored in real-time by the change in ionic current through the nanopores. Statistical analysis revealed that a lipid bilayer is formed from instantaneous rupture of individual vesicle upon adsorption in the nanopores, differing from the generally agreed mechanism that lipid bilayers form at a high vesicle surface coverage on a planar support. The dependence of the lipid-bilayer formation process as a function of applied bias, vesicle size and concentration was systematically studied. In addition, the non-fouling properties of the lipid bilayer coated nanopores were demonstrated during long single stranded DNA translocation through the nanopore array. The findings indicate that lipid bilayer formation process can be modulated by introducing nanocavities intentionally on the planar surface to create active sites or changing the vesicle size and concentration.

Advanced Science, 2019

Development of high sensitivity electronic sensors has attracted tremendous interest to meet urge... more Development of high sensitivity electronic sensors has attracted tremendous interest to meet urgent demands on portable devices for healthcare diagnostics and environmental monitoring. [1,2] In a common liquid sensing system, interaction between analytes and functional receptors at the liquid/solid

IEEE Sensors Journal, 2019

Solid-state nanopores (SSN) are of significant potential as a versatile tool for chemical sensing... more Solid-state nanopores (SSN) are of significant potential as a versatile tool for chemical sensing, biomolecule inspection, nanoparticle detection, etc. High throughput characterization of SSN in an arrayed format is highly desired for a wide range of applications. Herein, we demonstrate a novel design to integrate an SSN array with microfluidics and a multiplexer. Ionic current measurement on each nanopore can then be individually addressed fluidically and/or electrically with minimum cross talk (electric leakage). This integration provides a scalable platform for automated high-throughput, low-cost, and rapid electrical characterization potentially of a large number of SSN.

Nano Energy, 2019

Nanopores have been widely studied for power generation and single-molecule detection. Although t... more Nanopores have been widely studied for power generation and single-molecule detection. Although the power level generated by a single nanopore based on electrolyte concentration gradient is too low to be practically useful, such a power level is found sufficient to drive analyte translocation in nanopores. Here, we explore the simultaneous action of a solid-state nanopore as a nanopower generator and a nanoscale biosensor by exploiting the extremely small power generated to drive the analyte translocation in the same nanopore device. This autogenic analyte translocation is demonstrated using protein and DNA for their distinct shape, size and charge. The simple device structure allows for easy implementation of either electrical or optical readout. The obtained nanopore translocation is characterized by typical behaviors expected for an ordinary nanopore sensor powered by an external source. Extensive numerical simulation confirms the power generation and power level generated. It also reveals the fundamentals of autogenic translocation. As it requires no external power source, the sensing can be conducted with simple readout electronics and may allow for integration of high-density nanopores. Our approach demonstrated in this work may pave the way to practical high-throughput single-molecule nanopore sensing powered by the distributed energy harvested by the nanopores themselves.

Nanotechnology, 2019

Solid-state nanopores have drawn considerable attention for their potential applications in DNA s... more Solid-state nanopores have drawn considerable attention for their potential applications in DNA sequencing and nanoparticle analysis. However, fabrication of nanopores, especially those of diameter below 30 nm, requires sophisticated techniques. Here, a versatile method to controllablly reduce the diameter of prefabricated large-size pores down to sub-30 nm without greatly increasing the effective pore depth from the original membrane thickness is shown. This method exploits carbon deposition achieved via hydrocarbon evaporation, induced by an incident beam of electrons, and subsequent dissociation of hydrocarbon to solid carbon deposits. The carbon deposition employs a conventional scanning electron microscope equipped with direct visual feedback, along with a stable hydrocarbon source nearby the sample. This work systematically studies how electron-beam accelerating voltage, imaging magnification, initial pore size and membrane composition affect the process of pore size reduction. Secondary electrons generated in the membrane material are confirmed to be the main cause of the dissociation of hydrocarbon. Thicker carbon deposited on one side than on the other of the membrane results in an asymmetric nanopore shape and a rectifying ionic transport. A physico-phenomenological model combined with Monte Carlo simulations is proposed to account for the observed carbon deposition behaviors.

Nature Nanotechnology, 2019

The software released here can be used for training, validating and testing different ResNet arch... more The software released here can be used for training, validating and testing different ResNet architectures for counting translocation events and extracting statistical features from nanopore translocation signals (i.e. average translocation duration and amplitude in traces temporal chunks). The models are used in a supervised learning fashion and can be tested on experimental traces obtained in the lab. A Nanopore Translocation detector is currently under development in this release

This dataset contains a set of nanopore translocation current traces. It is divided in two parts.... more This dataset contains a set of nanopore translocation current traces. It is divided in two parts. <strong>Part I:</strong> This part contains artificially generated traces with different levels of background noise (SNR = 4, 2, 1, 0.5, and 0.25) For each noise level, three parameters are varied in data generation: a. Twenty different concentrations of nanoparticles as the analytes (Cnp): 0.013, 0.016, 0.020, 0.025, 0.032, 0.040, 0.050, 0.063, 0.080, 0.1, 0.13, 0.16, 0.20, 0.25, 0.32, 0.40, 0.50, 0.63, 0.80, and 1, with the unit of nano-molar, [nM]. b. Fifteen different diameters of the nanoparticles (Dnp): 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, and 17, with the unit of nanometer, [nm]. c. Five different translocation durations (Duration): 0.5, 1.0, 1.5, 3.0, and 5.0, with the unit of millisecond, [ms]. In total we have 20*15*5=1500 current traces for each SNR. There are three datasets: training, validation and test. Traces in training datasets are of 20 seconds,...

Journal of Biosensors and Bioelectronics, 2018

Single molecule detection is of vital importance for fundamental biotechnology research and pract... more Single molecule detection is of vital importance for fundamental biotechnology research and practical applications. Among the numerous single molecule detection techniques, solid-state nanopores have been developed as single molecule sensors for the investigation of unlabeled biopolymers such as DNA, RNA and protein owing to their robustness, pore size controllability and tunability of physical/chemical properties. The most commonly used method today to form ultra-small nanopores relies on using focused high energy electron beams on a transmission electron microscope (TEM). However, the sophisticated operation of TEM, high cost and low throughput limit its extensive applications. In this work, we start with electron beam lithography combined with reactive ion etching to massively prefabricate nanopores with relatively large size in free-standing silicon nitride membranes. Then, electron beam irradiation is used to deposit carbon with a conventional scanning electron microscope so as to reduce the size of prefabricated pores. This process leads to the controllable formation of solid-state carbon nanopores sub-30 nm in diameter. We subsequently use the carbon nanopores to study translocation of λ-DNA as a demonstration of the capability of such carbon nanopores. By tuning bias voltage, the translocation events show regular changes in amplitude, dwell time and appearance frequency. With this advanced nanopore platform, detection of single DNA molecules is achieved with a high signal-to-noise ratio of ~6

The model of diffusive O2 transport from capillary to tissue was established by Krogh a century a... more The model of diffusive O2 transport from capillary to tissue was established by Krogh a century ago. This model is incomplete as it ignores the often inevitable convective O2 transport via fluid movement. Here, we propose a one-dimensional physical-phenomenological model to evaluate the contribution of fluid movement to the O2 transport in tissue. Both the O2 gradient and the total O2 flux are found to be sensitive to the fluid movement. For small flow rates with a Peclet number Pe < 1, a critical flow rate, udc, is introduced to characterize the contribution of fluid movement to the O2 transport, as well as to evaluate the fluid contribution in O2-deficient tissues and the cytoplasm movement inside muscle fibers. During hemostasis, the O2 flux contributed by the interstitial flow even below a rate of 2 μm/s, although negligible near the capillary, can be significant for the tissue residing far from the capillary. For an isolated intramyocyte mitochondrion, the cytoplasm movement...

Solid-state nanopores (SSNPs) of on-demand shape and size can facilitate desired sensor performan... more Solid-state nanopores (SSNPs) of on-demand shape and size can facilitate desired sensor performance. However, reproducible production of arrayed nanopores of predefined geometry is yet to demonstrate despite of numerous methods explored. Here, bowl-shape SSNPs combining unique properties of ultrathin membrane and tapering geometry are demonstrated. The bowl-SSNP upper opening is 100-120 nm in diameter, with the bottom opening reaching sub-5 nm. Numerical simulation reveals the formation of multiple electroosmotic vortexes (EOVs) originating from distributed surface charge around the pore-bowl. The EOVs determine, collaboratively with electrophoretic force, how nanoscale objects translocate the bowl-SSNPs. Exceptional rectification with higher frequencies, longer duration and larger amplitude is found when DNA strands translocate downwards from the upper large opening than upwards from the bottom smallest restriction. The rectification is a manifestation of the interplay between elec...

Nano Energy, 2021

The tactile peripheral nervous system innervating human hands, which is essential for sensitive h... more The tactile peripheral nervous system innervating human hands, which is essential for sensitive haptic exploration and dexterous object manipulation, features overlapped receptive fields in the skin, arborization of peripheral neurons and many-to-many synaptic connections. Inspired by the structural features of the natural system, we report a supersensitive artificial slowly adapting tactile afferent nervous system based on the triboelectric nanogenerator technology. Using tribotronic transistors in the design of mechanoreceptors, the artificial afferent nervous system exhibits the typical adapting behaviours of the biological counterpart in response to mechanical stimulations. The artificial afferent nervous system is self-powered in the transduction and event-driven in the operation. Moreover, it has inherent proficiency of neuromorphic signal processing, delivering a minimum resolvable dimension two times smaller than the inter-receptor distance which is the lower limit of the dimension that existing electronic skins can resolve. These results open up a route to scalable neuromorphic skins aiming at the level of human's exceptional perception for neurorobotic and neuroprosthetic applications.

IEEE Electron Device Letters, 2020

Hysteresis is a frequently observed phenomenon in the transfer characteristics of thin film trans... more Hysteresis is a frequently observed phenomenon in the transfer characteristics of thin film transistors. Charge trapping/de-trapping processes of gate oxide and gate-channel interface are commonly known to be the origin of hysteresis and correlated to low frequency noise (LFN) properties of the devices. In this letter, a rapid four-point sweeping method (RFSM) is proposed to reveal the dependence of hysteresis, as well as the distribution of effective trap density on sweeping rate and gate bias range. Based on the RFSM, the hysteresis properties of four-layer MoS2 FETs are studied in detail. The experimental results demonstrate that the hysteresis and trap density at different frequencies and gate voltages, which could further roughly map the traps with different time constants and energy depths, can be obtained by the simple RFSM. Trap density estimated by RFSM shows a comparable range with that extracted from LFN, indicating that the traps inducing the hysteresis may also cause LFN.

Interfacing solid-state nanopores with biological systems has been exploited as a versatile analy... more Interfacing solid-state nanopores with biological systems has been exploited as a versatile analytical platform for analysis of individual biomolecules. Although clogging of solid-state nanopores due to nonspecific interactions between analytes and pore walls poses a persistent challenge in attaining the anticipated sensing efficacy, insufficient studies focus on elucidating the clogging dynamics. Herein, we investigate the DNA clogging behavior by passing double-stranded (ds) DNA molecules of different lengths through hafnium oxide(HfO 2)-coated silicon (Si) nanopore arrays, at different bias voltages and electrolyte pH values. Employing stable and photoluminescent-free HfO 2 /Si nanopore arrays permits a parallelized visualization of DNA clogging with confocal fluorescence microscopy. We find that the probability of pore clogging increases with both DNA length and bias voltage. Two types of clogging are discerned: persistent and temporary. In the time-resolved analysis, temporary clogging events exhibit a shorter lifetime at higher bias voltage. Furthermore, we show that the surface charge density has a prominent effect on the clogging probability because of electrostatic attraction between the dsDNA and the HfO 2 pore walls. An analytical model based on examining the energy landscape along the DNA translocation trajectory is developed to qualitatively evaluate the DNA−pore interaction. Both experimental and theoretical results indicate that the occurrence of clogging is strongly dependent on the configuration of translocating DNA molecules and the electrostatic interaction between DNA and charged pore surface. These findings provide a detailed account of the DNA clogging phenomenon and are of practical interest for DNA sensing based on solid-state nanopores.

Analytical Chemistry, 2019

This supporting information includes part of materials and methods section, the results of polyac... more This supporting information includes part of materials and methods section, the results of polyacrylamide gel electrophoresis (PAGE) and Quartz crystal microbalance (QCM) for aptamer-P1 hybridization. Moreover, supplementary EIS results as mentioned in the results and discussions section in the manuscript are also provided in this file.

IEEE Electron Device Letters, 2019

2015 IEEE 11th International Conference on ASIC (ASICON), 2015

Humidity sensors have attracted extensive attentions due to their various applications in environ... more Humidity sensors have attracted extensive attentions due to their various applications in environment monitoring, health care and internet of things. Graphene oxide has recently been exploited as a humidity sensing material because of its good hydrophilicity and excellent sensitivity. Here we report an ultra-sensitive and responsive capacitive humidity sensor using graphene oxide as sensing material. A capacitance change of ten times is observed when the relative humidity changes from 50% to 90%. The response and recovery time of the sensor are measured to be 0.066 and 0.154 s, respectively, which are several orders of magnitude shorter than conventional humidity sensors. Furthermore, its responses to flow rate, temperature and other vapors are also characterized.

Scientific reports, Jan 18, 2016

In the field of electronic gas sensing, low-dimensional semiconductors such as single-walled carb... more In the field of electronic gas sensing, low-dimensional semiconductors such as single-walled carbon nanotubes (SWCNTs) can offer high detection sensitivity owing to their unprecedentedly large surface-to-volume ratio. The sensitivity and responsivity can further improve by increasing their areal density. Here, an accelerated gas adsorption is demonstrated by exploiting volumetric effects via dispersion of SWCNTs into a percolating three-dimensional (3D) network in a semiconducting polymer. The resultant semiconducting composite film is evaluated as a sensing membrane in field effect transistor (FET) sensors. In order to attain reproducible characteristics of the FET sensors, a pulsed-gate-bias measurement technique is adopted to eliminate current hysteresis and drift of sensing baseline. The rate of gas adsorption follows the Langmuir-type isotherm as a function of gas concentration and scales with film thickness. This rate is up to 5 times higher in the composite than only with an ...

Nano Energy, 2014

In this paper, a flexible nanogenerator based on direct piezoelectric effect using a spin-coated ... more In this paper, a flexible nanogenerator based on direct piezoelectric effect using a spin-coated poly(vinylidenefluoride-co-trifluoroethylene) (PVDF-TrFE) thin film as functional layer has been fabricated on polyimide substrate. The as-prepared nanogenerator exhibits the open-circuit voltage up to 7 V and short-circuit current of 58 nA with current density of 0.56 μA/cm 2. The impact of the variation of strain rate on the electrical outputs of the nanogenerator has been characterized experimentally and analyzed theoretically. An analytical model that explains well the experimental results has been established.

Analytical Chemistry, 2019

Langmuir, 2020

Solid-state nanopores provide a highly versatile platform for rapid electrical detection and anal... more Solid-state nanopores provide a highly versatile platform for rapid electrical detection and analysis of single molecules. Lipid bilayer coating of the nanopores can reduce non-specific analyte adsorption to the nanopore sidewalls and increase the sensing selectivity by providing possibilities for tethering specific ligands in a cell-membrane mimicking environment. However, mechanism and kinetics of lipid bilayer formation from vesicles remain unclear in the presence of nanopores. In this work, we used a silicon-based, truncated-pyramidal nanopore array as the support for lipid bilayer formation. Lipid bilayer formation in the nanopores was monitored in real-time by the change in ionic current through the nanopores. Statistical analysis revealed that a lipid bilayer is formed from instantaneous rupture of individual vesicle upon adsorption in the nanopores, differing from the generally agreed mechanism that lipid bilayers form at a high vesicle surface coverage on a planar support. The dependence of the lipid-bilayer formation process as a function of applied bias, vesicle size and concentration was systematically studied. In addition, the non-fouling properties of the lipid bilayer coated nanopores were demonstrated during long single stranded DNA translocation through the nanopore array. The findings indicate that lipid bilayer formation process can be modulated by introducing nanocavities intentionally on the planar surface to create active sites or changing the vesicle size and concentration.

Advanced Science, 2019

Development of high sensitivity electronic sensors has attracted tremendous interest to meet urge... more Development of high sensitivity electronic sensors has attracted tremendous interest to meet urgent demands on portable devices for healthcare diagnostics and environmental monitoring. [1,2] In a common liquid sensing system, interaction between analytes and functional receptors at the liquid/solid

IEEE Sensors Journal, 2019

Solid-state nanopores (SSN) are of significant potential as a versatile tool for chemical sensing... more Solid-state nanopores (SSN) are of significant potential as a versatile tool for chemical sensing, biomolecule inspection, nanoparticle detection, etc. High throughput characterization of SSN in an arrayed format is highly desired for a wide range of applications. Herein, we demonstrate a novel design to integrate an SSN array with microfluidics and a multiplexer. Ionic current measurement on each nanopore can then be individually addressed fluidically and/or electrically with minimum cross talk (electric leakage). This integration provides a scalable platform for automated high-throughput, low-cost, and rapid electrical characterization potentially of a large number of SSN.

Nano Energy, 2019

Nanopores have been widely studied for power generation and single-molecule detection. Although t... more Nanopores have been widely studied for power generation and single-molecule detection. Although the power level generated by a single nanopore based on electrolyte concentration gradient is too low to be practically useful, such a power level is found sufficient to drive analyte translocation in nanopores. Here, we explore the simultaneous action of a solid-state nanopore as a nanopower generator and a nanoscale biosensor by exploiting the extremely small power generated to drive the analyte translocation in the same nanopore device. This autogenic analyte translocation is demonstrated using protein and DNA for their distinct shape, size and charge. The simple device structure allows for easy implementation of either electrical or optical readout. The obtained nanopore translocation is characterized by typical behaviors expected for an ordinary nanopore sensor powered by an external source. Extensive numerical simulation confirms the power generation and power level generated. It also reveals the fundamentals of autogenic translocation. As it requires no external power source, the sensing can be conducted with simple readout electronics and may allow for integration of high-density nanopores. Our approach demonstrated in this work may pave the way to practical high-throughput single-molecule nanopore sensing powered by the distributed energy harvested by the nanopores themselves.

Nanotechnology, 2019

Solid-state nanopores have drawn considerable attention for their potential applications in DNA s... more Solid-state nanopores have drawn considerable attention for their potential applications in DNA sequencing and nanoparticle analysis. However, fabrication of nanopores, especially those of diameter below 30 nm, requires sophisticated techniques. Here, a versatile method to controllablly reduce the diameter of prefabricated large-size pores down to sub-30 nm without greatly increasing the effective pore depth from the original membrane thickness is shown. This method exploits carbon deposition achieved via hydrocarbon evaporation, induced by an incident beam of electrons, and subsequent dissociation of hydrocarbon to solid carbon deposits. The carbon deposition employs a conventional scanning electron microscope equipped with direct visual feedback, along with a stable hydrocarbon source nearby the sample. This work systematically studies how electron-beam accelerating voltage, imaging magnification, initial pore size and membrane composition affect the process of pore size reduction. Secondary electrons generated in the membrane material are confirmed to be the main cause of the dissociation of hydrocarbon. Thicker carbon deposited on one side than on the other of the membrane results in an asymmetric nanopore shape and a rectifying ionic transport. A physico-phenomenological model combined with Monte Carlo simulations is proposed to account for the observed carbon deposition behaviors.

Nature Nanotechnology, 2019

The software released here can be used for training, validating and testing different ResNet arch... more The software released here can be used for training, validating and testing different ResNet architectures for counting translocation events and extracting statistical features from nanopore translocation signals (i.e. average translocation duration and amplitude in traces temporal chunks). The models are used in a supervised learning fashion and can be tested on experimental traces obtained in the lab. A Nanopore Translocation detector is currently under development in this release

This dataset contains a set of nanopore translocation current traces. It is divided in two parts.... more This dataset contains a set of nanopore translocation current traces. It is divided in two parts. <strong>Part I:</strong> This part contains artificially generated traces with different levels of background noise (SNR = 4, 2, 1, 0.5, and 0.25) For each noise level, three parameters are varied in data generation: a. Twenty different concentrations of nanoparticles as the analytes (Cnp): 0.013, 0.016, 0.020, 0.025, 0.032, 0.040, 0.050, 0.063, 0.080, 0.1, 0.13, 0.16, 0.20, 0.25, 0.32, 0.40, 0.50, 0.63, 0.80, and 1, with the unit of nano-molar, [nM]. b. Fifteen different diameters of the nanoparticles (Dnp): 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, and 17, with the unit of nanometer, [nm]. c. Five different translocation durations (Duration): 0.5, 1.0, 1.5, 3.0, and 5.0, with the unit of millisecond, [ms]. In total we have 20*15*5=1500 current traces for each SNR. There are three datasets: training, validation and test. Traces in training datasets are of 20 seconds,...