Publications by authors named "Jake Rabinowitz"

5 Publications

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mr-EBL: ultra-high sensitivity negative-tone electron beam resist for highly selective silicon etching and large-scale direct patterning of permanent structures.

Nanotechnology 2021 Mar 11. Epub 2021 Mar 11.

Department of Electrical Engineering, Columbia University, New York, UNITED STATES.

Electron beam lithography (EBL) is the state-of-the-art technique for rapid prototyping of nanometer-scale devices. Even so, processing speeds remain limited for the highest resolution patterning. Here, we establish mr-EBL as the highest throughput negative tone electron-beam-sensitive resist. The 10µC/cm2 dose requirement enables fabricating a 100 mm2 photonic diffraction grating in a ten minute EBL process. Optimized processing conditions achieve a critical resolution of 75 nm with 3x faster write speeds than SU-8 and 1-2 orders of magnitude faster write speeds than maN-2400 and HSQ. Notably, these conditions significantly differ from the manufacturers' recommendations for the recently commercialized mr-EBL resist. We demonstrate mr-EBL to be a robust negative etch mask by etching silicon trenches with aspect ratios of 10 and near-vertical sidewalls. Furthermore, our optimized processing conditions are suitable to direct patterning on integrated circuits or delicate nanofabrication stacks, in contrast to other negative tone EBL resists. In conclusion, mr-EBL is a highly attractive EBL resist for rapid prototyping in nanophotonics, MEMS, and fluidics.
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http://dx.doi.org/10.1088/1361-6528/abededDOI Listing
March 2021

Nanobubble-controlled nanofluidic transport.

Sci Adv 2020 Nov 13;6(46). Epub 2020 Nov 13.

Department of Electrical Engineering, Columbia University, New York, NY 10027, USA.

Nanofluidic platforms offering tunable material transport are applicable in biosensing, chemical detection, and filtration. Prior studies have achieved selective and controllable ion transport through electrical, optical, or chemical gating of complex nanostructures. Here, we mechanically control nanofluidic transport using nanobubbles. When plugging nanochannels, nanobubbles rectify and occasionally enhance ionic currents in a geometry-dependent manner. These conductance effects arise from nanobubbles inducing surface-governed ion transport through interfacial electrolyte films residing between nanobubble surfaces and nanopipette walls. The nanobubbles investigated here are mechanically generated, made metastable by surface pinning, and verified with cryogenic transmission electron microscopy. Our findings are relevant to nanofluidic device engineering, three-phase interface properties, and nanopipette-based applications.
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http://dx.doi.org/10.1126/sciadv.abd0126DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7673748PMC
November 2020

An Electrically Actuated, Carbon-Nanotube-Based Biomimetic Ion Pump.

Nano Lett 2020 02 30;20(2):1148-1153. Epub 2019 Dec 30.

Department of Electrical Engineering , Columbia University , New York , New York 10027 , United States.

Single-walled carbon nanotubes (SWCNTs) are well-established transporters of electronic current, electrolyte, and ions. In this work, we demonstrate an electrically actuated biomimetic ion pump by combining these electronic and nanofluidic transport capabilities within an individual SWCNT device. Ion pumping is driven by a solid-state electronic input, as Coulomb drag coupling transduces electrical energy from solid-state charge along the SWCNT shell to electrolyte inside the SWCNT core. Short-circuit ionic currents, measured without an electrolyte potential difference, exceed 1 nA and scale larger with increasing ion concentrations through 1 M, demonstrating applicability under physiological (∼140 mM) and saltwater (∼600 mM) conditions. The interlayer coupling allows ionic currents to be tuned with the source-drain potential difference and electronic currents to be tuned with the electrolyte potential difference. This combined electronic-nanofluidic SWCNT device presents intriguing applications as a biomimetic ion pump or component of an artificial membrane.
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http://dx.doi.org/10.1021/acs.nanolett.9b04552DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7018576PMC
February 2020

Nanoscale Fluid Vortices and Nonlinear Electroosmotic Flow Drive Ion Current Rectification in the Presence of Concentration Gradients.

J Phys Chem A 2019 Sep 16;123(38):8285-8293. Epub 2019 Jul 16.

Department of Chemistry , University of Utah , Salt Lake City , Utah 84112 , United States.

Ion current rectification (ICR) is a transport phenomenon in which an electrolyte conducts unequal currents at equal and opposite voltages. Here, we show that nanoscale fluid vortices and nonlinear electroosmotic flow (EOF) drive ICR in the presence of concentration gradients. The same EOF can yield negative differential resistance (NDR), in which current decreases with increasing voltage. A finite element model quantitatively reproduces experimental ICR and NDR recorded across glass nanopipettes under concentration gradients. The model demonstrates that spatial variations of electrical double layer properties induce the nanoscale vortices and nonlinear EOF. Experiments are performed in conditions directly related to scanning probe imaging and show that quantitative understanding of nanoscale transport under concentration gradients requires accounting for EOF. This characterization of nanopipette transport physics will benefit diverse experimentation, pushing the resolution limits of chemical and biophysical recordings.
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http://dx.doi.org/10.1021/acs.jpca.9b04075DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6911310PMC
September 2019

Flexible Nanopipettes for Minimally Invasive Intracellular Electrophysiology In Vivo.

Cell Rep 2019 01;26(1):266-278.e5

Department of Biological Sciences, Columbia University, New York, NY 10027, USA; NeuroTechnology Center, Columbia University, New York, NY 10027, USA; Kavli Institute for Brain Science, Columbia University, New York, NY 10027, USA.

Intracellular recordings in vivo remains the best technique to link single-neuron electrical properties to network function. Yet existing methods are limited in accuracy, throughput, and duration, primarily via washout, membrane damage, and movement-induced failure. Here, we introduce flexible quartz nanopipettes (inner diameters of 10-25 nm and spring constant of ∼0.08 N/m) as nanoscale analogs of traditional glass microelectrodes. Nanopipettes enable stable intracellular recordings (seal resistances of 500 to ∼800 MΩ, 5 to ∼10 cells/nanopipette, and duration of ∼1 hr) in anaesthetized and awake head-restrained mice, exhibit minimal diffusional flux, and facilitate precise recording and stimulation. When combined with quantum-dot labels and microprisms, nanopipettes enable two-photon targeted electrophysiology from both somata and dendrites, and even paired recordings from neighboring neurons, while permitting simultaneous population imaging across cortical layers. We demonstrate the versatility of this method by recording from parvalbumin-positive (Pv) interneurons while imaging seizure propagation, and we find that Pv depolarization block coincides with epileptic spread. Flexible nanopipettes present a simple method to procure stable intracellular recordings in vivo.
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http://dx.doi.org/10.1016/j.celrep.2018.12.019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7263204PMC
January 2019