Capitalizing on the G7 Research Compact.

Rules for S&T collaboration should be integrated with trade and investment agreements.

Ultralow Acoustic Loss Micromachined Butterfly Lamb Wave Resonators on AlN Plates.

This study reports the design of a novel Butterfly Lamb wave resonator (LWR) employing the S0 mode in the AlN plate, and for the first time, its ultrahigh parallel-resonance quality factor ( Qp ) of 4,021 is demonstrated, indicating an ultralow acoustic loss. Although the series resonance quality factor ( Qs ) is widely used for various loss comparisons, it is inconclusive since Qs is always dominated by the routing resistance ( Rs ), which is normally huge without the thick metal rewiring. Instead, Qp is a precise representation of the acoustic loss level for its independence of Rs and as it is closer to Qmax of the Bode Q -curve in the IDT-excited devices. A butterfly-shaped resonance cavity, theoretically predicted to reduce the anchor loss and suppress the transverse spurious mode, has been applied to the AlN LWR and experimentally shown to boost the Qp by 2.3 times. In addition, a directly measured Bode- Q curve for the LWR is reported for the first time, showing superior Q profile for the Butterfly-LWR than the conventional-LWR and good agreement with the 3 dB- Qp 's.

Gel-seq: A Method for Simultaneous Sequencing Library Preparation of DNA and RNA Using Hydrogel Matrices.

The ability to amplify and sequence either DNA or RNA from small starting samples has only been achieved in the last five years. Unfortunately, the standard protocols for generating genomic or transcriptomic libraries are incompatible and researchers must choose whether to sequence DNA or RNA for a particular sample. Gel-seq solves this problem by enabling researchers to simultaneously prepare libraries for both DNA and RNA starting with 100 - 1000 cells using a simple hydrogel device. This paper presents a detailed approach for the fabrication of the device as well as the biological protocol to generate paired libraries. We designed Gel-seq so that it could be easily implemented by other researchers; many genetics labs already have the necessary equipment to reproduce the Gel-seq device fabrication. Our protocol employs commonly-used kits for both whole-transcript amplification (WTA) and library preparation, which are also likely to be familiar to researchers already versed in generating genomic and transcriptomic libraries. Our approach allows researchers to bring to bear the power of both DNA and RNA sequencing on a single sample without splitting and with negligible added cost.

Monitoring of the central blood pressure waveform via a conformal ultrasonic device.

Continuous monitoring of the central-blood-pressure waveform from deeply embedded vessels, such as the carotid artery and jugular vein, has clinical value for the prediction of all-cause cardiovascular mortality. However, existing non-invasive approaches, including photoplethysmography and tonometry, only enable access to the superficial peripheral vasculature. Although current ultrasonic technologies allow non-invasive deep-tissue observation, unstable coupling with the tissue surface resulting from the bulkiness and rigidity of conventional ultrasound probes introduces usability constraints. Here, we describe the design and operation of an ultrasonic device that is conformal to the skin and capable of capturing blood-pressure waveforms at deeply embedded arterial and venous sites. The wearable device is ultrathin (240 µm) and stretchable (with strains up to 60%), and enables the non-invasive, continuous and accurate monitoring of cardiovascular events from multiple body locations, which should facilitate its use in a variety of clinical environments.

Gel-seq: whole-genome and transcriptome sequencing by simultaneous low-input DNA and RNA library preparation using semi-permeable hydrogel barriers.

The advent of next generation sequencing has fundamentally changed genomics research. Unfortunately, standard protocols for sequencing the genome and the transcriptome are incompatible. This forces researchers to choose between examining either the DNA or the RNA for a particular sample. Here we describe a new device and method, collectively dubbed Gel-seq, that enables researchers to simultaneously sequence both DNA and RNA from the same sample. This technology makes it possible to directly examine the ways that changes in the genome impact the transcriptome in as few as 100 cells. The heart of the Gel-seq protocol is the physical separation of DNA from RNA. This separation is achieved electrophoretically using a newly designed device that contains several different polyacrylamide membranes. Here we report on the development and validation of this device. We present both the manufacturing protocol for the device and the biological protocol for preparing genetic libraries. Using cell lines with uniform expression (PC3 and Hela), we show that the libraries generated with Gel-seq are similar to those developed using standard methods for either RNA or DNA. Furthermore, we demonstrate the power of Gel-seq by generating a matched genome and transcriptome library from a sample of 100 cells collected from a mouse liver tumor.

Energy harvesting from cerebrospinal fluid pressure fluctuations for self-powered neural implants.

In this paper, a novel method to generate electrical energy by converting available mechanical energy from pressure fluctuations of the cerebrospinal fluid within lateral ventricles of the brain is presented. The generated electrical power can be supplied to the neural implants and either eliminate their battery need or extend the battery lifespan. A diaphragm type harvester comprised of piezoelectric material is utilized to convert the pressure fluctuations to electrical energy. The pressure fluctuations cause the diaphragm to bend, and the strained piezoelectric materials generate electricity. In the framework of this study, an energy harvesting structure having a diameter of 2.5 mm was designed and fabricated using microfabrication techniques. A 1:1 model of lateral ventricles was 3D-printed from raw MRI images to characterize the harvester. Experimental results show that a maximum power of 0.62 nW can be generated from the harvester under similar physical conditions in lateral ventricles which corresponds to energy density of 12.6 nW/cm2. Considering the available area within the lateral ventricles and the size of harvesters that can be built using microfabrication techniques it is possible to amplify to power up to 26 nW. As such, the idea of generating electrical energy by making use of pressure fluctuations within brain is demonstrated in this work via the 3D-printed model system.

Improved Dielectric Properties of Polyvinylidene Fluoride Nanocomposite Embedded with Poly(vinylpyrrolidone)-Coated Gold Nanoparticles.

A novel nanocomposite dielectric was developed by embedding polyvinylpyrrolidone (PVP)-encapsulated gold (Au) nanoparticles in the polyvinylidene fluoride (PVDF) polymer matrix. The surface functionalization of Au nanoparticles with PVP facilitates favorable interaction between the particle and polymer phase, enhancing nanoparticle dispersion. To study the effect of entropic interactions on particle dispersion, nanocomposites with two different particle sizes (5 and 20 nm in diameter) were synthesized and characterized. A uniform particle distribution was observed for nanocomposite films consisting of 5 nm Au particles, in contrast to the film with 20 nm particles. The frequency-dependent dielectric permittivity and the loss tangent were studied for the nanocomposite films. These results showed the effectiveness of PVP ligand in controlling the agglomeration of Au particles in the PVDF matrix. Moreover, the study showed the effect of particle concentration on their spatial distribution in the polymer matrix and the dielectric properties of nanocomposite films.

Physical Delivery of Macromolecules using High-Aspect Ratio Nanostructured Materials.

There is great need for the development of an efficient delivery method of macromolecules, including nucleic acids, proteins, and peptides, to cell cytoplasm without eliciting toxicity or changing cell behavior. High-aspect ratio nanomaterials have addressed many challenges present in conventional methods, such as cell membrane passage and endosomal degradation, and have shown the feasibility of efficient high-throughput macromolecule delivery with minimal perturbation of cells. This review describes the recent advances of in vitro and in vivo physical macromolecule delivery with high-aspect ratio nanostructured materials and summarizes the synthesis methods, material properties, relevant applications, and various potential directions.

Self-Transport of Condensed Liquid in Micro Cooling Device Using Distributed Meniscus Pumping.

This paper reports a reliable passive micro pump system combining the physical properties of a tapered microchannel and sharp microstructures. This tailored microchannel with triple-spike microstructures was created to transport condensed liquid into the reservoir chamber in a micro cooling device and in the case of chip off-mode prepare the next cooling cycle before chip on-mode, allowing the reliable and continuous circulation of coolant without liquid being trapped in the vapor channel causing dryout limitation. At the tapered channel end, the pinned liquid meniscus was distributed by a middle spike and then continued to overflow into the condenser chamber due to extended capillary action.

Focused energy field method for the localized synthesis and direct integration of 1D nanomaterials on microelectronic devices.

In the focused energy field method, localized heating, and convective mass transfer in a liquid precursor realizes selective synthesis and direct integration of 1D nanomaterials as well as their surface functionalization, all in a low-temperature, liquid environment. This allows facile fabrication of 1D nanomaterial-based nanoelectronic devices.

Refillable and magnetically actuated drug delivery system using pear-shaped viscoelastic membrane.

We report a refillable and valveless drug delivery device actuated by an external magnetic field for on-demand drug release to treat localized diseases. The device features a pear-shaped viscoelastic magnetic membrane inducing asymmetrical deflection and consecutive touchdown motion to the bottom of the dome-shaped drug reservoir in response to a magnetic field, thus achieving controlled discharge of the drug. Maximum drug release with 18 ± 1.5 µg per actuation was achieved under a 500 mT magnetic flux density, and various controlled drug doses were investigated with the combination of the number of accumulated actuations and the strength of the magnetic field.

All-in-one nanowire-decorated multifunctional membrane for rapid cell lysis and direct DNA isolation.

This paper describes a handheld device that uses an all-in-one membrane for continuous mechanical cell lysis and rapid DNA isolation without the assistance of power sources, lysis reagents, and routine centrifugation. This nanowire-decorated multifunctional membrane was fabricated to isolate DNA by selective adsorption to silica surface immediately after disruption of nucleus membranes by ultrasharp tips of nanowires for a rapid cell lysis, and it can be directly assembled with commercial syringe filter holders. The membrane was fabricated by photoelectrochemical etching to create microchannel arrays followed by hydrothermal synthesis of nanowires and deposition of silica. The proposed membrane successfully purifies high-quality DNA within 5 min, whereas a commercial purification kit needs more than an hour.

Caterpillar locomotion-inspired valveless pneumatic micropump using a single teardrop-shaped elastomeric membrane.

This paper presents a microfluidic pump operated by an asymmetrically deformed membrane, which was inspired by caterpillar locomotion. Almost all mechanical micropumps consist of two major components of fluid halting and fluid pushing parts, whereas the proposed caterpillar locomotion-inspired micropump has only a single, bilaterally symmetric membrane-like teardrop shape. A teardrop-shaped elastomeric membrane was asymmetrically deformed and then consecutively touched down to the bottom of the chamber in response to pneumatic pressure, thus achieving fluid pushing. Consecutive touchdown motions of the teardrop-shaped membrane mimicked the propagation of a caterpillar's hump during its locomotory gait. The initial touchdown motion of the teardrop-shaped membrane at the centroid worked as a valve that blocked the inlet channel, and then, the consecutive touchdown motions pushed fluid in the chamber toward the tail of the chamber connected to the outlet channel. The propagation of the touchdown motion of the teardrop-shaped membrane was investigated using computational analysis as well as experimental studies. This caterpillar locomotion-inspired micropump composed of only a single membrane can provide new opportunities for simple integration of microfluidic systems.

Hierarchical silicon nanospikes membrane for rapid and high-throughput mechanical cell lysis.

This letter reports an efficient and compatible silicon membrane combining the physical properties of nanospikes and microchannel arrays for mechanical cell lysis. This hierarchical silicon nanospikes membrane was created to mechanically disrupt cells for a rapid process with high throughput, and it can be assembled with commercial syringe filter holders. The membrane was fabricated by photoelectrochemical overetching to form ultrasharp nanospikes in situ along the edges of the microchannel arrays. The intracellular protein and nucleic acid concentrations obtained using the proposed membrane within a short period of time were quantitatively higher than those obtained by routine, conventional acoustic and chemical lysis methods.

Photoactuators and motors based on carbon nanotubes with selective chirality distributions.

Direct conversion of light into mechanical work, known as the photomechanical effect, is an emerging field of research, largely driven by the development of novel molecular and polymeric material systems. However, the fundamental impediment is that the previously explored materials and structures do not simultaneously offer fast and wavelength-selective response, reversible actuation, low-cost fabrication and large deflection. Here, we demonstrate highly versatile photoactuators, oscillators and motors based on polymer/single-walled carbon nanotube bilayers that meet all the above requirements. By utilizing nanotubes with different chirality distributions, chromatic actuators that are responsive to selected wavelength ranges are achieved. The bilayer structures are further configured as smart 'curtains' and light-driven motors, demonstrating two examples of envisioned applications.

Multi-temperature zone, droplet-based microreactor for increased temperature control in nanoparticle synthesis.

Microreactors are an emerging technology for the controlled synthesis of nanoparticles. The Multi-Temperature zone Microreactor (MTM) described in this work utilizes thermally isolated heated and cooled regions for the purpose of separating nucleation and growth processes as well as to provide a platform for a systematic study on the effect of reaction conditions on nanoparticle synthesis.

Solar-blind photodetectors for harsh electronics.

We demonstrate solar-blind photodetectors (PDs) by employing AlN thin films on Si(100) substrates with excellent temperature tolerance and radiation hardness. Even at a bias higher than 200 V the AlN PDs on Si show a dark current as low as ~ 1 nA. The working temperature is up to 300°C and the radiation tolerance is up to 10(13) cm(-2) of 2-MeV proton fluences for AlN metal-semiconductor-metal (MSM) PDs. Moreover, the AlN PDs show a photoresponse time as fast as ~ 110 ms (the rise time) and ~ 80 ms (the fall time) at 5 V bias. The results demonstrate that AlN MSM PDs hold high potential in next-generation deep ultraviolet PDs for use in harsh environments.

Rigid, vapor-permeable poly(4-methyl-2-pentyne) templates for high resolution patterning of nanoparticles and polymers.

Soft lithography methods are emerging as useful tools for high-resolution, three-dimensional patterning of polymers and nanoparticles. However, the low Young's modulus of the standard template material, poly(dimethylsiloxane) (PDMS), limits attainable resolution, fidelity, and alignment capability. While much research has been performed to find other more rigid polymer template materials, the high solvent and vapor permeability that is characteristic of PDMS is often sacrificed, preventing their use in those processes reliant on this property. In this work, a highly rigid, chemically robust, optically transparent and vapor-permeable poly(4-methyl-2-pentyne) template is developed. The combination of high rigidity and high vapor permeability enables high resolution patterning with simplified ink handling. This material was nanopatterned to create a template for patterning polymers and nanoparticles, achieving a resolution of better than 350 nm.

Simultaneous patterning of nanoparticles and polymers using an evaporation driven flow in a vapor permeable template.

Nanoparticles and polymers have great potential for lowering cost and increasing functionality of printed sensors and electronics. However, creation of practical devices requires that many of these materials be patterned on a single substrate, and many current patterning processes can only handle a single material at a time, necessitating alignment of serial processing steps. Higher throughput and lower cost can be achieved by patterning multiple materials simultaneously. To this end, the microfluidic molding process is adapted to pattern various nanoparticle and polymer inks simultaneously, in a completely additive manner, with three-dimensional control and high relative positional accuracy between the different materials. A differential template distortion observed in channels containing different inks is analyzed and found to result from pressure force in the template due to flow of a highly viscous and highly concentrated ink in small channels. The resulting optimization between patterning speed and dimensional fidelity is discussed.

AlN/3C-SiC composite plate enabling high-frequency and high-Q micromechanical resonators.

An AlN/3C-SiC composite layer enables the third-order quasi-symmetric (QS(3)) Lamb wave mode with a high quality factor (Q) characteristic and an ultra-high phase velocity up to 32395 ms(-1). A Lamb wave resonator utilizing the QS(3) mode exhibits a low motional impedance of 91 Ω and a high Q of 5510 at a series resonance frequency (f(s)) of 2.92 GHz, resulting in the highest f(s)·Q product of 1.61 × 10(13) Hz among the suspended piezoelectric thin film resonators reported to date.