Micro and Nano Systems Letters最新文献

The present work proposes a method for fabricating metallic Al particles in aqueous solution. An aqueous colloidal solution was prepared from an aqueous aluminum nitrate nonahydrate solution by electrolysis using metallic Al plates as the anode and cathode under ultrasonic irradiation in water at 25–45 °C. The sizes of the particles in the colloidal solutions prepared at 25, 35, and 45 °C were 76.3, 77.0, and 84.7 nm, respectively. The powder obtained from the colloidal solution prepared at 25 °C was not crystalline. By contrast, the powders obtained from the colloidal solutions prepared at 35 and 45 °C had a crystal structure of cubic Al and crystal sizes of 55.7 and 59.3 nm, respectively. Thus, elevated temperatures promoted both particle growth and crystal growth, which was explained by higher temperatures increasing the frequency and energy of particle collisions. The metallic Al particles were chemically stable in both an aqueous solution and the ambient atmosphere. The chemically stable metallic Al particles are expected to be used as sources for fabricating materials related to fuels, energy storage, and pigments.

LC CMOS voltage-controlled oscillators (VCOs) with tunable inductors are essential for high-performance, multi-band communication systems, such as IoT applications and 5G communication. However, VCOs that use CMOS tunable inductors have difficulty in achieving high RF performance due to the low Q-factor of the inductor. In addition, previously reported CMOS VCOs integrated with MEMS inductors have used CMOS switches for tuning frequency bands, but they also had large signal losses on the switch. Herein, we propose a CMOS VCO that is integrated with a MEMS tunable inductor that tunes the frequency band with three MEMS switches. The proposed MEMS tunable inductor enables us to achieve high RF performance due to the suspended structure, and RF MEMS switches enable lower signal loss than CMOS switches. In this work, we successfully fabricated the proposed CMOS VCO integrated with a MEMS tunable inductor using the flip-chip bonding process, and we measured oscillation frequencies according to the actuation of the three switches. The oscillation powers were measured as − 3.03 dBm @ 1.39 GHz, − 5.80 @ 1.98 GHz, − 7.44 dBm @ 2.81 GHz, and − 8.77 dBm @ 3.68 GHz.

Colloidal Silver nano-particles were grown at room temperature using leaf extract of Ocimum tenuiflorum. The silver nanoparticles suspended in the solution were found to be stable for over a period of 2 months. Structural, optical and photo catalytic behavior of the suspended silver (Ag) nano-particles (NPs) was characterized. From TEM analysis the size of the silver nanoparticles was estimated to be 25–30 nm. Our findings suggest that the ratio between the molarity of AgNO3 and the volume of leaf extract does not have any role in controlling the size of the Ag nano-particles. These green synthesized Ag nano-particles exhibit degradation of the carcinogenic organic pollutant sulforhodamine B in absence of light.

Conventional pain assessment methods such as patients’ self-reporting restrict the possibility of easy pain monitoring while pain serves as an important role in clinical practice. Here we report a pain assessment method via 3D face reading camera assisted by dot pattern illumination. The face reading camera module (FRCM) consists of a stereo camera and a dot projector, which allow the quantitative measurement of facial expression changes without human subjective judgement. The rotational offset microlens arrays (roMLAs) in the dot projector form a uniform dense dot pattern on a human face. The dot projection facilitates evaluating three-dimensional change of facial expression by improving 3D reconstruction results of non-textured facial surfaces. In addition, the FRCM provides consistent pain rating from 3D data, regardless of head movement. This pain assessment method can provide a new guideline for precise, real-time, and continuous pain monitoring.

In the present work, gas sensor arrays consisted of four different sensing materials based on CuO and their depositions on the MEMS microheaters were designed, fabricated and characterized. The sensor array is consisted with CuO, CuO with Pt NPs, ZnO–CuO and ZnO–CuO with Au NPs and their gas sensing properties are characterized for detection of exhaled breath-related VOCs. Through MEMS microheaters, power consumption is considered for application to healthcare devices which requires ultrasensitive acetone gas sensitivity. Also, using the principal component analysis, it enables to discriminate acetone gas, a biomarker for fat burning during diet, with other VOCs gases. The device would be applicable for on-site diet monitoring in the field of mobile healthcare.

Studies related to low temperature and their effect on cardiomyocytes are essential as hypothermia—like situations have been known to induce arrhythmia or ventricular fibrillation. Till date, several studies have been carried out on animals and their electrophysiological responses have been studied in the form of action potential. However, for a complete assessment of the effect of low temperature, mechanophysiological changes along with electrophysiological changes need to be investigated, at the tissue level. In this study, the effect of culture temperature on cell growth has been studied by measuring the field potential and contractility of human induced pluripotent stem cell-derived cardiomyocytes. This study has the potential to further improve the understanding of low temperature on human cells.

Gold nanoparticles (Au NPs) based technology has been shown to possess enormous potential in the viral nucleic acid diagnosis. Despite significant advancement in this domain, the existing literature reveals the diversity in the conditions employed for hybridization and tagging of thiolated nucleic acid probes over the Au NPs. Here we employ the probe sequence derived from the Hepatitis C virus to identify the optimal hybridization and thiol-Au NP tagging conditions. In a typical polymerase chain reaction, the probes are initially subjected to flash heating at elevated temperatures to obtain efficient annealing. Motivated by this, in the current study, the hybridization between the target and the antisense oligonucleotide (ASO) has been studied at 65 °C with and without employing flash heating at temperatures from 75 to 95 °C. Besides, the efficiency of the thiolated ASO’s tagging over the Au NPs with and without citrate buffer has been explored. The study has revealed the beneficial role of flash heating at 95 °C for efficient hybridization and the presence of citrate buffer for rapid and effective thiol tagging over the Au NPs. The combinatorial effect of these conditions has been found to be advantageous in enhancing the sensitivity of ratiometric genosensing using Au NPs.

Bicelle is one of the most stable phospholipid assemblies, which has tremendous applications in the research areas for drug delivery or structural studies of membrane proteins owing to its bio-membrane mimicking characteristics and high thermal stability. However, the conventional preparation method for bicelle demands complicated manufacturing processes and a long time so that the continuous synthesis method of bicelle using microfluidic chip has been playing an important role to expand its feasibility. We verified the general availability of hydrodynamic focusing method with microfluidic chip for bicelle synthesis using various kinds of lipids which have a phase transition temperature ranged from − 2 to 41 °C. Bicelle can be formed only when the inside temperature of microfluidic chip was over the phase transition temperature. Moreover, the concentration condition for bicelle formation varied depending on the lipids. Furthermore, the transition process characteristics from bicelle to vesicle were analyzed by effective q-value, mixing time and dilution condition. We verified that the size of transition vesicles was controlled according to the effective q-value, mixing time, and temperature.

Thickness-controlled transparent conducting films (TCFs) were fabricated by transfer printing a 100 nm thick Cu micromesh structure onto poly(vinyl alcohol) (PVA) substrates of different thicknesses (~ 50, ~ 80, and ~ 120 μm) to develop a lightweight transparent wearable heater with short response time. The Cu mesh-based TCF fabricated on a ~ 50 µm thick PVA substrate exhibited excellent optical and electrical properties with a light transmittance of 86.7% at 550 nm, sheet resistance of ~ 10.8 Ω/sq, and figure-of-merit of approximately 236, which are comparable to commercial indium tin oxide film-based transparent conductors. The remarkable flexibility of the Cu mesh-based TCF was demonstrated through cyclic mechanical bending tests. In addition, the Cu mesh-based TCF with ~ 50 μm thick PVA substrate demonstrated a fast Joule heating performance with a thermal response time of ~ 18.0 s and a ramping rate of ~ 3.0 ℃/s under a driving voltage of 2.5 V. Lastly, the reliable response and recovery characteristics of the Cu mesh/PVA film-based transparent heater were confirmed through the cyclic power test. We believe that the results of this study is useful in the development of flexible transparent heaters, including lightweight deicing/defogging films, wearable sensors/actuators, and medical thermotherapy pads.