Innovative Micro Technology (United States)

Optimal synthesis parameters for hydrothermal growth of nine ZnO nanostructure morphologies as a durable, homogeneous coating have been determined.

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.

ABSTRACT Successful wafer-level packaged MEMS devices need hermeticity and reliability testing to prevent failure from particles, contamination, moisture, among other factors. Unfortunately, legacy hermeticity test protocols fail when applied to the measurement of micron-sized volume of cavities, where MEMS devices typically reside. Recently, higher resolution and more accurate test methods have evolved in market. When combined with standard reliability tests, MEMS manufacturers can ensure they ship high quality products. Reliability is a critical parameter to take into consideration; if a product does not deliver the design performance during its expected lifetime it cannot be commercialized. Reliability in MEMS devices is particularly important because failure can be time consuming and costly. Assurance of reliability involves intelligent design, reliable test strategies, and accurate testing techniques. Selecting the right test(s) depends on the MEMS device and how the device needs to perform in the field. Engineers cannot design reliable MEMS without first understanding the factors that can lead to failure and how to test for these factors.

We have batch fabricated suspended nanochannel resonators (SNRs) to improve the mass resolution of suspended microchannel resonators (SMRs). 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 640 kHz and exhibits the maximum quality factor of approximately 16,000 when dry and when filled with water. Using the SNRs, we demonstrated mass measurements of various nanoparticles down to 20 nm in diameter and viruses in solution with a resolution of 27 ag in a 1 kHz bandwidth, which represents a 100-fold improvement over existing SMRs and, to our knowledge, is the most precise mass measurement in liquid today.

Nanomechanical resonators enable the measurement of mass with extraordinary sensitivity. Previously, samples as light as 7 zeptograms (1 zg = 10(-21) g) have been weighed in vacuum, and proton-level resolution seems to be within reach. Resolving small mass changes requires the resonator to be light and to ring at a very pure tone-that is, with a high quality factor. In solution, viscosity severely degrades both of these characteristics, thus preventing many applications in nanotechnology and the life sciences where fluid is required. Although the resonant structure can be designed to minimize viscous loss, resolution is still substantially degraded when compared to measurements made in air or vacuum. An entirely different approach eliminates viscous damping by placing the solution inside a hollow resonator that is surrounded by vacuum. Here we demonstrate that suspended microchannel resonators can weigh single nanoparticles, single bacterial cells and sub-monolayers of adsorbed proteins in water with sub-femtogram resolution (1 Hz bandwidth). Central to these results is our observation that viscous loss due to the fluid is negligible compared to the intrinsic damping of our silicon crystal resonator. The combination of the low resonator mass (100 ng) and high quality factor (15,000) enables an improvement in mass resolution of six orders of magnitude over a high-end commercial quartz crystal microbalance. This gives access to intriguing applications, such as mass-based flow cytometry, the direct detection of pathogens, or the non-optical sizing and mass density measurement of colloidal particles.

MEMS industry has seen mixed success over the last decade or so. Today, there are only a limited number of MEMS products available on the market, notably airbag accelerometers, desktop inkjet print heads and pressure sensors for automotive and biomedical applications. Despite major infusion of funds in other applications, such as optical telecommunications, RF, and biomedical/microfluidics, these efforts have failed to produce working MEMS in high volumes. The net result is that MEMS have not yet lived up to their anticipated promise.

Covers advancements in spacecraft and tactical and strategic missile systems, including subsystem design and application, mission design and analysis, materials and structures, developments in space sciences, space processing and manufacturing, space operations, and applications of space technologies to other fields.