查看更多>>摘要：Over the past two decades,digital microfluidic biochips have been in much demand for safety-critical and biomedical applications and increas-ingly important in point-of-care analysis,drug discovery,and immunoassays,among other areas.However,for complex bioassays,finding routes for the transportation of droplets in an electrowetting-on-dielectric digital biochip while maintaining their discreteness is a challenging task.In this study,we propose a deep reinforcement learning-based droplet routing technique for digital microfluidic biochips.The technique is implemented on a distributed architecture to optimize the possible paths for predefined source-target pairs of droplets.The actors of the technique calculate the possible routes of the source-target pairs and store the experience in a replay buffer,and the learner fetches the expe-riences and updates the routing paths.The proposed algorithm was applied to benchmark suites Ⅰ and Ⅲ as two different test benches,and it achieved significant improvements over state-of-the-art techniques.
查看更多>>摘要：Giant magnetostrictive actuators(GMAs)are a widely used type of micro-nano actuator,and they are greatly significant in the field of precision engineering.The accuracy of a GMA often depends on its hysteresis model.However,existing models have some limitations,including the difficulty of identifying their parameters and the tradeoff between the quantity of modeling data required and the level of precision achieved.To solve these problems,in this paper,we propose a Preisach inverse model based on equal-density segmentation of the weight function(E-Preisach).The weight function used to calculate the displacement is first discretized.Then,to obtain a finer weight distribution,the discretized geometric units are uniformly divided by area.This can further minimize the output displacement span,and it produces a higher-precision hysteresis model.The process of parameter identification is made easier by this approach,which also resolves the difficulty of obtaining high precision using a small amount of modeling data.The Preisach and the E-Preisach inverse models were investigated and compared using experiments.At frequencies of 1 and 5 Hz,it was found that the E-Preisach inverse model decreases the maximum error of the feedforward compensation open-loop control to within 1 pm and decreases the root-mean-square error in displacement to within 0.5 pm without the need to increase the number of measured hysteresis loops.As a result,the E-Preisach inverse model streamlines the structure of the model and requires fewer parameters for modeling.This provides a high-precision modeling method using a small amount of modeling data;it will have applications in precision engineering fields such as active vibration damping and ultra-precision machining.
查看更多>>摘要：Microfluidic phenotyping methods have been of vital importance for cellular characterization,especially for evaluating single cells.In order to study the deformability of a single cell,we devised and tested a tunable microfluidic chip-based method.A pneumatic polymer polydimethyl-siloxane(PDMS)membrane was designed and fabricated abutting a single-cell trapping structure,so the cell could be squeezed controllably in a lateral direction.Cell contour changes under increasing pressure were recorded,enabling the deformation degree of different types of single cell to be analyzed and compared using computer vision.This provides a new perspective for studying mechanical properties of cells at the single cell level.
查看更多>>摘要：As a metal alloy,NiCr films have a relatively high resistivity and low temperature coefficient of resistance(TCR)and are widely used in electronic components and sensors.However,the resistivity of pure NiCr is insufficient for high-resistance and highly stable film resistors.In this study,a quaternary NiCrAlSi target(47∶33∶10∶10,wt.％)was successfully used to prepare resistor films with resistivities ranging from 1000 to 10 000 pΩ cm and TCR within±100 ppm/K.An oxygen flow was introduced during the sputtering process.The films exhibit high-temperature stability at 450 ℃.The films were analyzed using Auger electron spectroscopy,x-ray diffraction,time-of-flight secondary-ion mass spectrometry,and x-ray photoelectron spectroscopy.The results show that the difference in the oxide proportion of the films caused the differences in resistivity.The near-zero TCR values were considered to be due to the competition between silicon and other metals.This study provides new insights into the electrical properties of NiCr-based films containing Si,which will drive the manufacturing of resistors with high resistivity and zero TCR.
查看更多>>摘要：Nanoparticles with non-spherical shapes are now being widely used for various photonic applications.We observe experimentally that the magnitude as well as the time dependence of the transient absorption of a colloid of silver nanoplatelets depends on the relative polarization of the pump and probe pulses.There have been a few reports about the dependence of the transient signal magnitude on polarization,but little information is available on its temporal dependence.Using a theoretical model,we show that this observed behavior arises from the fact that the energy absorption by a non-spherical nanoparticle depends on,among other factors,the nanoparticle orientation with respect to the pump and probe polarization directions.It is essential to consider this when estimating nanoparticle characteristics such as carrier thermalization time,carrier-phonon scattering time,and complex polarizability from transient absorption measurements.
查看更多>>摘要：Copper-based nanomaterials have been widely used in catalysis,electrodes,and other applications due to their unique electron-transfer properties.In this work,an efficient electrochemical sensor based on an electrode modified with one-dimensional Cu(OH)2/carboxymethyl cellulose(CMC)composite nanofibers was fabricated and investigated for the detection of aspirin.Scanning electron microscopy was employed to examine the morphological characteristics of these composite nanofibers.Cyclic voltammetry and electrochemical impedance spectroscopy were used to assess the electrochemical performance of a Cu(OH)2/CMC composite nanofiber-modified electrode.The find-ings indicate that the modified electrode has a very high sensitivity to aspirin.The observed enhanced performance could be a result of the high surface-to-volume ratio of the composite nanofibers and their superior electron-transport characteristics,which may hasten electron transfer between aspirin and the surfaces of the modified electrode.This detection technique also demonstrated strong selectivity for aspirin.These findings imply that the technique can be applied as a highly effective and selective approach to aspirin measurement in biological science.
查看更多>>摘要：With the development of modern industry and ever more complex structural loads,the possibility of fatigue failure is increasing.Fatigue analysis can be used to evaluate the service life of components and reduce the probability of accidents.Therefore,the development and application of fatigue-analysis technology have important research significance.This paper collects information from a wide field of literature and summarizes the current status of fatigue-analysis research.It covers related theoretical knowledge,fatigue-life prediction methods,and fatigue design methods and their application scenarios,and it summarizes the challenges and research hotspots in the field.On the basis of this examination,future development directions of fatigue-life prediction methods are proposed.The conclusions will have a certain guiding role in the development of fatigue-analysis methods.
NETL
NSTL
万方数据
维普