Solid-state Micro Research Articles

Anisotropic Temperature-Driven Strain Dynamics in VO2 Solid-State Microactuators

VO2 is a particularly appealing material for the development of solid-state micro- and nanoactuators due to its phase transition characterized by a large lattice change associated with a high energ...

(Invited) Nanoengineered Thermoelectric Energy Devices for IoT Sensing Applications

Flexible thermoelectric micro power generators have been developed for wearable devices such as body area network. Also in order to store the generated power, a solid state micro-supercapacitor using a thin film composed of graphene nanowall are developed. The flexible thermoelectric micro power generator is fabricated by electrochemical deposition of Bi2Te3 and Sb2Te3, which is embedded by PDMS as shown in Fig. 1 (1). A power generation of 4 μW/cm2 are demonstrated from human body temperature. In order to improve the power generation performance, nanocomposites processes of Bi2Te3 are developed. In this method, nanomaterials such as metal nanoparticles and carbon nanomaterials are included in the film by a co-electrodeposition method (Fig. 2). For the fabrication of the solid state micro super capacitor, plasma-enhanced chemical vapor deposition is used to deposit graphene nanowall on a spiral-shaped silicon electrode pattern, as shown in Fig. 3. On the graphene nanowall Ru oxide or Ni oxide is deposited for electrochemical charge storage layer. Areal energy density of ~15 μWh/cm2 and areal power density of ~2.49 mW/cm2 are achieved (2). References (1) T. N. Huu, T. Nguyen, and T. Ono, "Fabrication of π-type flexible thermoelectric generators using an electrochemical deposition method for thermal energy harvesting applications at room temperature" Journal of Micromechanics and Microengineering 27, (2017) 125006. (2) J. Li, M. Zhu, Z. An, Z. Wang, M. Toda, T. Ono, Constructing in-chip micro-supercapacitors of 3D graphene nanowall/ruthenium oxides electrode through silicon-based microfabrication technique, Journal of Power Sources 401, (2018) 204-212. Figure 1

Two-Axis Solid-State Microgyroscope on Surface Acoustic Waves

This article focuses on the development of a two-axis solid state micro gyroscope (SMG) on surface acoustic waves (SAW). The described gyroscope belongs to the category of inexpensive sensing elements featuring a high degree of longtime overload stability. This advantage seems to make SAW SMGs a priority choice for navigation and control systems functioning in severe overload environments of up to 65,000 g. As of today SAW SMGs are designed according to a number of known principles. Such SMGs may also operate on standing SAWs or traveling SAWs. This article addresses the first gyro type. Unfortunately, the existing standing SAW SMGs share a common limitation of measuring angular rates in relation to one axis only. This research attempts to introduce an innovative two-axis standing SAW SMG. The influence of the basis rotation on the parameters of the elastic waves traveling within the substrate layer was carefully studied. Incident and reflected wave models were also elaborated. The numerical simulation results demonstrate the effects of the basis rotation on the complex factors of the volume waves reflected by the substrate layer and on the phase velocity and frequency thereof as well as on the oscillation amplitude of the particles involved in SAW transition, and on the elliptical particle movement path configuration. Also, the SAW SMG is compared to the existing micromechanical gyroscopes, and the basic SAW SMG production technologies are reviewed.

Chemical vapor deposition of hexagonal boron nitride on metal-coated wafers and transfer-free fabrication of resistive switching devices

Due to their outstanding electronic and physical properties, two-dimensional (2D) materials have attracted much interest for the fabrication of solid-state microelectronic devices. Among all methods to synthesize 2D materials, chemical vapor deposition (CVD) is the most attractive in the field of solid-state microelectronics because it can produce high quality 2D material in a scalable manner. However, the high temperatures (>900 °C) required during the CVD growth of the 2D materials impede their direct synthesis on metal-coated wafers due to prohibitive metal diffusion and de-wetting. This makes necessary carrying out the 2D materials CVD growth independently on metallic foils, and transfer them on the wafers using polymer scaffolds. However, this process is slower, more expensive, and can lead to abundant contamination and cracks in the 2D material. Here we present a facile method to allow the direct growth of multilayer hexagonal boron nitride (h-BN) on Ni-coated Si wafers, which consists on placing a protective cover 30 μm above the Ni surface. The resulting h-BN stacks have been used to fabricate Au/Ti/h-BN/Ni memristors with low cycle-to-cycle variability. This work contributes to the integration of 2D materials in solid-state micro- and nano-electronic technologies.

Identifying Single Particles in Air Using a 3D-Integrated Solid-State Pore.

Solid-state micro- and nanopores are a versatile sensor platform capable of detecting single particles in electrolyte solution by cross-pore ionic current. Here we report on a use of this technology to identify airborne particulate matter. The detection concept lies in an electrophoretic control of air-floating particles captured in liquid to deliver them into a pore detector via microfluidic channels. We demonstrate resistive pulse measurements to machine-learning-based discriminations of intragranular contents of cypress and cedar pollens at a single-particle level. This all-electrical-sensor technique would pave a new venue toward real-time monitoring of single particles and molecules in air.

Manufacturing of a Nafion-coated, Reduced Graphene Oxide/Polyaniline Chemiresistive Sensor to Monitor pH in Real-time During Microbial Fermentation.

Here, we report the engineering of a solid-state micro pH sensor based on polyaniline-functionalized, electrochemically reduced graphene oxide (ERGO-PA). Electrochemically reduced graphene oxide acts as the conducting layer and polyaniline acts as a pH-sensitive layer. The pH-dependent conductivity of polyaniline occurs by doping of holes during protonation and by the dedoping of holes during deprotonation. We found that an ERGO-PA solid-state electrode was not functional as such in fermentation processes. The electrochemically active species that the bacteria produce during the fermentation process interfere with the electrode response. We successfully applied Nafion as a proton-conducting layer over ERGO-PA. The Nafion-coated electrodes (ERGO-PA-NA) show a good sensitivity of 1.71 Ω/pH (pH 4 - 9) for chemiresistive sensor measurements. We tested the ERGO-PA-NA electrode in real-time in the fermentation of Lactococcus lactis. During the growth of L. lactis, the pH of the medium changed from pH 7.2 to pH 4.8 and the resistance of the ERGO-PA-NA solid-state electrode changed from 294.5 Ω to 288.6 Ω (5.9 Ω per 2.4 pH unit). The pH response of the ERGO-PA-NA electrode compared with the response of a conventional glass-based pH electrode shows that reference-less solid-state microsensor arrays operate successfully in a microbiological fermentation.

Evolution of Diamond based Microdosimetry

The requirements for solid state micro- dosimetry particularly within the context of medical and space environments necessitate a tissue equivalent and radiation hard material, for which diamond is uniquely suited. An overview of the current status of diamond based microdosimetry is given. This overview will explore previous and current technologies developed by the Centre for Medical Radiation Physics (CMRP). The overview will analyse technologies in terms of their advantages and disadvantages within the context of microdosimetry. Using this as a basis, recommendations with respect to fabri- cation methodologies/techniques are provided in order to direct the course and progress of development so as to achieve true diamond based microdosimetry.

Direct measurement of the magnetocaloric effect on micrometric Ni-Mn-(In,Sn) ribbons by the mirage effect under pulsed magnetic field

In this work, we report on the direct measurement of the magnetic field induced temperature change in a series of micrometric thick ribbons of Ni-Mn-In-Sn Heusler alloys, performed with an innovative experimental technique based on the thermo-optical “Mirage Effect.” The technique combines very fast measurement time, 1 T pulsed magnetic field in the millisecond range, and contactless temperature detection. These features make the technique ideal for the characterization of thin samples with a thickness down to a few micrometers. In this work, we demonstrate this by directly measuring the magnetocaloric effect (MCE) of micrometric-thick ribbons of Heusler alloys at the Curie transition, which was tuned on a wide temperature range by varying the Sn to In ratio. The direct test of the MCE in thin samples is fundamental for the development of refrigerant elements with a large heat-transfer coefficient and for the design of solid state micro devices for cooling and energy harvesting.

Generation of Terahertz Radiation Spectra by Radiation Sources Based on Solid-State Micro- and Nanostructures and Detection of Terahertz Spectra

Principles and mechanisms of generation of terahertz electromagnetic oscillations by generators based on solid-state micro- and nanostructures are discussed. Parameters of experimental models of such devices are given. A theoretical model of terahertz radiation in magnetic metal junctions is presented, and the possibility of varying the frequency of a spin-injection terahertz oscillator is demonstrated. The results of development of methods for examining the spectral characteristics of radiation in the 0.15–80 THz range with a spectral resolution of up to 1.8 GHz are detailed.

Polyaniline functionalized electrochemically reduced graphene oxide chemiresistive sensor to monitor the pH in real time during microbial fermentations

Here we report potentiometric and chemiresistive pH sensing performance of polyaniline functionalized Electrochemically reduced graphene oxide (ERGO-PA) to monitor pH change in Lactococcus lactis fermentation continuously in real time. We found that polyaniline functionalized graphene oxide as such, cannot be used in a fermentation process to monitor pH. A lot of interference was observed from electrochemically active redox species that are produced during the bacterial growth. We have successfully employed a simple Nafion coating on top of the ERGO-PA to avoid interferences. The Nafion coated electrodes show a good sensitivity of 55 mV/pH (pH 2–9) and 1.71 Ω/pH (pH 4–9) for potentiometric and chemiresistive sensor measurements, respectively. Real time pH measurements of Nafion coated ERGO-PA in a L. lactis fermentation show that it can be used for continuous pH measurements in complex biological growth media. Effectiveness of ERGO-PA-NA solid state chemiresistive pH sensor in complex fermentation process shows that reference less solid state micro sensors can be fabricated and could be used in e.g. multi micro bioreactor screening platforms.

Optical Characterization of a Thin-Film Material Based on Light Intensity Measurements

Light interacts with materials in a variety of ways; this article focuses on determination of refraction and absorption characterized by a material’s refractive index. We discuss some of the useful models for the frequency dependence of the refractive index, and practical approaches to calculating refractive indices of thin films and thick substrates. The efficiency of manufacturing of existing and successful creation of new devices of solid-state micro- and nanoelectronics largely depends on the level of development of the technology for manufacturing layers of various materials with a thickness of several nanometers to tens of micrometers. A high degree of perfection of layered structures and particularly structures based on dielectric and/or metallic films with nanometer thickness is needed for their successful application in micro-, nano-, acousto-, microwave and optoelectronics. It is impossible to achieve high degree of perfection without the use of high-precision methods of measuring electrophysical parameters of dielectric and semiconductor materials and structures, metallic films. We have developed the program “Multilayer”, which serves both to simulate the propagation of light through multilayer thin-film layered media, and to determine the dielectric (permittivity tensor of anisotropic films) and geometric (physical and optical thicknesses of the film) parameters of various thin-film coatings. The base mathematical models applied for the description of the light wave propagation through a homogeneous optical medium and for the determination of the optical characteristics of thin layers of optical materials based on the results of light intensity measurements are described. The main mathematical formalism employed in the program is based on solving the Maxwell’s equations for propagation of light through anisotropic stratified media. The algorithm uses the Berreman matrices of order

Interfacial reactions in molten state micro solder joints under current stressing

The high local temperature in flip-chip solder joints of microprocessors has raised concerns that the solder, a low melting temperature alloy, might locally liquefy and consequently cause failure of the micro solder joint. This article reports the electromigration (EM) behavior when the solder is in the molten state. The electronic current was applied to the Cu/Sn-3.0Ag-0.5Cu (SAC305)/Cu molten solder joints. The growth of the intermetallic compound (IMC) and the consumption of the Cu pad were investigated. Moreover, the transition of IMC 3-D morphologies was also studied by the deep-etching method after EM test. The results of the electromigration in the molten solder joints indicate that the growth of the interface IMC and the consumption of the Cu pad present similar trends with those in the solid state micro solder joints, however, the rates of the growth and consumption are higher than those in the solid state micro solder joints. The evolution of IMC 3-D morphologies during the electromigration in the molten solder joints shows its own unique features, which are different from the electromigration in the solid state solder joints. With the increase of stressing time, the IMC 3-D morphologies transition indicates that the average grain size of cathodic Cu6Sn5 increases in radial direction with the increase of stressing time, but the size first increases, and then decreases in axial direction. In contrast to the morphologies transition for cathodic Cu6Sn5, the average grain size of anode Cu6Sn5 increases not only in radial direction but also in axial direction.

Randomly polarised beam produced by magnetooptically Q-switched laser

Diode-pumped solid-state micro lasers are compact (centimetre-scale), highly stable, and efficient. Previously, we reported Q-switched lasers incorporating rare-earth substituted iron garnet (RIG) film. Here, the first demonstration of the magnetooptical (MO) Q-switch in an Nd:YAG laser cavity is performed. We fabricate a quasi-continuous-wave (QCW) diode-pumped Nd:YAG laser cavity, which is shortened to 10 mm in length and which contains an RIG film and a pair of small coils. This cavity yields a 1,064.58-nm-wavelength pulse with 25-ns duration and 1.1-kW peak power at a 1-kHz repetition ratio. Further, the polarisation state is random, due to the isotropic crystal structure of Nd:YAG and the fact that the MO Q-switch incorporating the RIG film does not require the presence of polarisers in the cavity. This is also the first report of an MO Q-switch producing random polarisation.

Preparation of solid-state micro- and nanocellular acrylonitrile-butadiene-styrene (ABS) foams using sub- and supercritical CO2 as blowing agents

In this work, micro- and nanocellular acrylonitrile-butadiene-styrene (ABS) foams were prepared by using sub- and supercritical CO2 as blowing agents. The sorption kinetics at 10MPa was first measured. The sorption amount depended on the saturation temperature Arrheniusly. The diffusivities did not follow the Arrhenius relation. This relation was interpreted by a retrograde behavior of ABS/CO2 system. From the kinetics, ABS discs were saturated at 10MPa at the temperatures from −20°C to 40°C, and foamed at the foaming temperature of 20°C–80°C. A network of closed cells with a diameter of 600–700nm and nanopores with a diameter of 100nm were observed in the foam obtained at low saturation temperatures and high foaming temperatures. The closed cell densities were in a range from 1.12×1012−9.87×1012 cells/cm3 and an experimental correlation based on the CNT model was used to fit the data.

Abstract 48: Differentiation of Moderate and Severe Ischemic Heart Failure by Invasive and Non-invasive Assessments of Diastolic Function in a Rat Model of Chronic Heart Failure

Background: This work is designed to determine if specific left ventricle (LV) pressure-volume relations, hemodynamic, and echo derived parameters of diastolic function are able to separate severe from moderate CHF in rats with left coronary artery occlusion. Hypothesis: Echocardiographic indices of diastolic function, end-diastolic pressure (EDP), dead volume, stiffness constants (k), and pressure volume relations predict the severity of CHF in infarcted rats. Methods: Male Sprague Dawley rats (N=14) were randomized to undergo left coronary artery ligation or sham operation. Echocardiography was performed at 3 and 6 weeks post coronary ligation. The rats were categorized into moderate or severe CHF according to their LVEDP at 6 weeks post ligation. Invasive hemodynamic measurements with solid state micro manometer pressure catheters as well as diastolic pressure-volume relation values were obtained at the 6 week end point. Results: Moderate and severe CHF rats had significantly (P<0.05) elevated left ventricular (LV) end-diastolic pressure (LV EDPs), prolonged time constants of LV relaxation (tau), and decreased peak development pressures. When moderate versus severe CHF rats were separated based on LV EDP, early diastolic anterior wall radial relaxation velocity as well as e’, and E/e’ had strong correlations with invasive hemodynamic measurements of diastolic functions. There was a trend towards decreased compliance as measured by stiffness constants in severe heart failure group. Differences (P<0.05) in dead volume, mean arterial pressure (MAP), tau, and ejection fraction (EF) were also displayed. End diastolic pressure-volume analyses illustrated significant differences in plot positioning and curvature. Conclusion: While it is possible to separate rats with moderate and severe CHF in the rat coronary artery ligation model, the separation is not simply based on a specific EF value. This work may be useful in deciding whether there is a differential effect of new treatments for severe versus moderate CHF.

Tu1229 Endoluminal Functional Lumen Imaging Probe (EndoFLIP) During Peroral Endoscopic Myotomy (POEM) for Achalasia Predicts Postoperative Clinical Success: A Multicenter Case-Control Study

Background: Anorectal manometry is useful in evaluating and planning treatment in patients with fecal incontinence (FI) and other disorders of defecation. Traditional water perfusion techniques are limited to 4 to 8 radial measurements obtained via a pullback technique. Three-dimensional high resolution anorectal manometry (3D HRAM) employs solid state micro transducers and can obtain 257 data points during resting, squeeze, and bear down (simulated defecation) sequences. Data are then reconstructed into a 3D format showing functional anatomy. While differences are known to exist between patients with FI and obstruction, patients with mixed disorders (of FI and obstruction) are less well described Objective: To determine physiologic differences between groups of female patients with FI, obstructed defecation, and mixed disorders. In addition to known parameters of mean resting pressure and maximal squeeze pressure, relationships between rectoanal pressure differential and percent anal relaxation were sought among the groups. Methods Retrospective chart review of 50 female patients undergoing 3D HRAM between 1/1/ 13 and 6/1/14. Physiologic values including mean resting, and maximal squeeze pressures, percent anal relaxation, and rectoanal pressure differential were recorded. Analysis of variance test, and linear regression analysis was performed as appropriate. Results:Women with mixed defecatory disorders had sphincter pressure profiles that were significantly different from patients with pure FI or obstruction (table). While rectoanal pressure differential was not different among the groups, patients with mixed disorders had a significant linear relationship between rectoanal pressure differential and percent anal relaxation that was not seen among the pure FI or obstructed groups (figure). Conclusion: Mixed defecatory disorders are associated with a unique physiologic profile that can be characterized using 3D HRAM. The mixed defecatory group demonstrates relationships between physiologic parameters that are not seen the incontinent or obstructed groups. This data will be helpful in the planning treatment regimens.

Closed loop driving and detect circuit of piezoelectric solid-state micro gyroscope

Piezoelectric solid-state micro gyroscope is a novel kind of rotating rate sensor, which is based on the special thickness-shear vibrating mode of a piezoelectric body. Compared with the general vibratory micro gyroscope, it has no evident mass-spring component in its structure, so it has larger stiffness and robust resistance to shake and strike. Therefore, piezoelectric solid-state micro gyroscope can be used in the high-g environment. In this paper, piezoelectric solid-state micro gyroscope working principle is described. The closed loop driving and detect circuit of piezoelectric solid-state micro gyroscope is proposed in order to track the resonance frequency drift, stabilize the driving voltage value and detect the gyroscope output. The closed loop driving circuit (CLDC) mainly contains phase lock loop circuit, automatic gain circuit. Detect circuit mainly contains de-modulator, difference amplifier, Phase shift circuit and low pass filter. Experimental results show that the frequency of CLDC fluctuates within ±15 Hz with the resonance frequency of 357.9 kHz when get its stable status and the fluctuation of reference voltage is within ±7 mv, while the fluctuation of reference voltage in open loop driving circuit is ±23 mv. In the experiment, the sensitivity of the gyroscope with 740 mv/rad/s is observed. The work in the paper provides the theoretical and experimental foundation for realizing for this kind of gyroscope.

Study on Driving Technology of Piezoelectric Solid-State Micro Gyroscope

In order to compensate the noise brought by piezoelectric gyroscope or external environment and track the resonance frequency, Closed Loop Driving Circuit (CLDC) of piezoelectric solid-state micro gyroscope is proposted in the paper which will stabilize the driving voltage value and keep the resonance frequency tracked. CLDC mainly contains Phase Lock Loop (PLL) circuit, Automatic Gain Circuit (AGC). Experimental results show that the fluctuation of reference voltage is within ±7mv, while the fluctuation of reference voltage in Open Loop Driving Circuit (OLDC) without noise compensation is ±23mv. The frequency of CLDC drifts within 0.03 kHz with the resonance frequency of 357.9 kHz while the OLDC can’t track any drifting.

Magnetocaloric cooling of a thermally-isolated microstructure

A solid-state micro magnetic refrigerator (SSMMR) has some advantages to cool microdevices because of its high efficiency and simple structure. In this study, we demonstrated the actual cooling of a thermally-isolated microstructure, which is a main component of the SSMMR, by the magnetocaloric effect. The thermal isolation structure is composed of parylene high-aspect-ratio beams for both high thermal isolation and high stiffness. A magnetic field switch was designed and fabricated to control the magnetic flux density from 0 T to about 1 T. Under this magnetic flux density change, the maximum temperature change of 1.0 °C was confirmed.

Novel Three-Axis Solid-state Micro Accelerometer with Surrounding Beam Structure

This study presents the design, fabrication and characterization of an ultra miniaturized 3-axis accelerometer based on micro/nanoelectromechanical systems (MEMS/NEMS). This accelerometer designed and fabricated as small as with overall dimensions 700μmX700μmX550μm length width and thickness, respectively. It can detect three components of acceleration simultaneously.. The sensitivity could be enhanced significantly while miniaturizing the die size of sensor chip with the aid of novel structure and nano-scale piezoresistors on the sensing beams. Therefore, this novel proposed sensor is showing good performance and smaller than other comparable miniaturized sensor structures reported thus far. The accelerometer is capable of measuring accelerations up to ±50g in the frequency bandwidth of 300Hz accordance with finite element simulation.