Toward Attogram Mass Measurements in Solution with Suspended Nanochannel Resonators

Using suspended nanochannel resonators (SNRs) we demonstrate measurements of mass in solution with a resolution of 27 ag in a 1 kHz bandwidth, which represents a 100-fold improvement over existing suspended microchannel resonators and, to our knowledge, is the most precise mass measurement in liquid today. The SNR consists of a cantilever that is 50 μm long, 10 μm wide, and 1.3 μm thick, with an embedded nanochannel that is 2 μm wide and 700 nm tall. The SNR has a resonance frequency near 630 kHz and exhibits a quality factor of approximately 8,000 when dry and when filled with water. In addition, we introduce a new method that uses centrifugal force caused by vibration of the cantilever to trap particles at the free end. This approach eliminates the intrinsic position dependent error of the SNR and also improves the mass resolution by increasing the averaging time for each particle.Center for Integration of Medicine and Innovative Technology (CIMIT Contract 09-440)United States. Army Research Office (Institute for Collaborative Biotechnologies Grant (DAAD1903D0004))Max Planck Institute for Biophysical Chemistr

Suspended nanochannel resonators at attogram precision

Nanomechanical resonators can quantify individual particles down to a single atom; however the applications are limited due to their degraded performance in solution. Suspended micro- and nanochannel resonators can achieve vacuum level performances for samples in solution since the target analyte flows through an integrated channel within the resonator. Here we report on a new generation suspended nanochannel resonator (SNR) that operates at approximately 2 MHz with quality factors between 10,000-20,000. The SNR is measured to have a mass sensitivity of 8.2 mHz/attogram. With an optimized oscillator system, we show that the resonator can be oscillated with a mass equivalent frequency stability of 0.85 attogram (4 parts-perbillion) at 1 kHz bandwidth, which is 1.8 times the calculated stability imposed by the thermal noise. We demonstrate the use of this mass resolution by quantifying the mass and concentration of nanoparticles down to 10 nm in solution

Measuring single cell mass, volume, and density with dual suspended microchannel resonators

Cell size, measured as either volume or mass, is a fundamental indicator of cell state. Far more tightly regulated than size is density, the ratio between mass and volume, which can be used to distinguish between cell populations even when volume and mass appear to remain constant. Here we expand upon a previous method for measuring cell density involving a suspended microchannel resonator (SMR). We introduce a new device, the dual SMR, as a high-precision instrument for measuring single-cell mass, volume, and density using two resonators connected by a serpentine fluidic channel. The dual SMR designs considered herein demonstrate the critical role of channel geometry in ensuring proper mixing and damping of pressure fluctuations in microfluidic systems designed for precision measurement. We use the dual SMR to compare the physical properties of two well-known cancer cell lines: human lung cancer cell H1650 and mouse lymphoblastic leukemia cell line L1210.National Cancer Institute (U.S.) (Koch Institute Support (Core) Grant P30-CA14051)National Cancer Institute (U.S.). Physical Sciences Oncology Center (U54CA143874)National Cancer Institute (U.S.). Cell Decision Process Center (P50GM68762)National Institutes of Health (U.S.) (Contract R01GM085457

Electrically curable double-layer polymer resist for dynamic nanoscale lithography

A double-layer polymer resist composed of a top electrically curable resin layer with onium salt photo-acid generators and a bottom ionic conductive polymer transfer layer has been developed for dynamic nanoscale electric lithography. By applying an electric potential on the resist from conductive patterns on a mask, the acid generators under the conductive patterns are electrolyzed into proton acid, which consequently cross-links the cationically polymerizable resin resist. With the double-layer resist, nanopatterns can be generated with a sub-50 nm resolution. By applying different electric potentials on the individual conductive patterns on the mask, the transferred nanopatterns can be modified dynamically

RESISTANCE OF LIQUID METAL DROPLETS AGAINST ACTUATION ON MICROSTRUCTURED SURFACES

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A Micromechanical Switch with Electrostatically Driven Liquid-Metal Droplet

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A micromechanical switch with electrostatically driven liquid-metal droplet

This paper presents the use of a microscale liquid-metal droplet as a contact and moving part in a micromechanical switch with electrostatic actuation. Design, FEM analysis, fabrication and testing of the device are reported. The droplet is driven by a given voltage bias that induces electrostatic force between a grounded liquid-metal and an imbedded actuation electrode. The electrodes and the liquid-metal droplet are placed inside of an anisotropically etched silicon cavity. A novel technique to make shadow masks utilizing thin wafers is used to pattern the electrodes inside the silicon cavity. (C) 2002 Elsevier Science B.V. All rights reserved.X113838sciescopu

Driving Principle and Stability Analysis of Vertical Comb-Drive Actuator for Scanning Micromirrors

We have developed a manufacturing process for micromirrors based on microelectromechanical systems (MEMS) technology. The process involves designing an electrostatic vertically comb-driven actuator and utilizing a self-alignment process to produce a height difference between the movable comb structure and the fixed comb structure of the micromirror. To improve the stability of the micromirror, we propose four instability models in micromirror operation with the quasi-static driving principle and structure of the micromirror considered, which can provide a basic guarantee for the performance of vertical comb actuators. This analysis pinpoints factors leading to instability, including the left and right gap of the movable comb, the torsion beams of the micromirror, and the comb-to-beams distance. Ultimately, the voltages at which device failure occurs can be determined. We successfully fabricated a one-dimensional micromirror featuring a 0.8 mm mirror diameter and a 30 μm device layer thickness. The height difference between the movable and fixed comb structures was 10 μm. The micromirror was able to achieve a static mechanical angle of 2.25° with 60 V@DC. Stable operation was observed at voltages below 60 V, in close agreement with the theoretical calculations and simulations. At the driving voltage of 80 V, we observed the longitudinal displacement movement of the comb fingers. Furthermore, at a voltage of 129 V, comb adhesion occurred, resulting in device failure. This failure voltage corresponds to the lateral torsional failure voltage