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Proceedings of Micromachines 2021 — 1st International Conference on Micromachines and Applications (ICMA2021)最新文献

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Experimental studies of the sedimentation, stability and thermal conductivity of two different nanofluids 两种不同纳米流体的沉降、稳定性和导热性的实验研究
R. R. Souza, V. Faustino, I. Gonçalves, J. Miranda, A. Moita, A. Moreira, M. Bañobre‐López, R. Lima
: Fluids containing nanometer-sized particles (nanofluids, NFs) are potential candidates to improve the performance and efficiency of several thermal devices at micro- and macro-scale levels. However, the problem of sedimentation and instability of these colloidal dispersions has been the biggest obstacle for industrial-scale applications. In this work, two different NFs were tested using distilled water (DI-Water) as the base fluid. The first is a traditional NF formed by Al2O3 nanoparticles (NPs) with 50 nm diameter, and the second is a novel NF formed by poly (acrylic acid)-coated iron oxide NPs (Fe3O4@PAA) with ~10 nm diameter, obtained through a hydrothermal synthesis process. The main objective of this study was to evaluate the colloidal stability of these NFs over time using different volume fractions and compare it with DI-Water. Results involving sedimentation studies and zeta potential measurements showed that the proposed Fe3O4@PAA NF presents a higher colloidal stability compared to that of the Al2O3 NF. Additionally, thermal conductivity measurements were performed in both Fe3O4@PAA and Al2O3 NFs at different NP concentrations, using the transient plane source technique. Results showed higher thermal conductivity values for the Fe3O4@PAA NFs compared to those of Al2O3 NFs. However, a linear enhancement of thermal conductivity with increasing NPs concentration was observed for the Al2O3 NF over the whole range of NP concentrations tested, whereas two different regimes were observed for the Fe3O4@PAA NF.
含有纳米颗粒的流体(纳米流体,NFs)是在微观和宏观水平上提高几种热器件性能和效率的潜在候选者。然而,这些胶体分散体的沉降和不稳定性问题一直是工业规模应用的最大障碍。在这项工作中,用蒸馏水(DI-Water)作为基液对两种不同的NFs进行了测试。第一种是由直径为50 nm的Al2O3纳米颗粒(NPs)形成的传统NF,第二种是由聚丙烯酸包覆直径为~10 nm的氧化铁纳米颗粒(Fe3O4@PAA)通过水热合成而成的新型NF。本研究的主要目的是使用不同的体积分数来评估这些NFs随时间的胶体稳定性,并将其与DI-Water进行比较。沉降研究和zeta电位测量结果表明,与Al2O3 NF相比,Fe3O4@PAA NF具有更高的胶体稳定性。此外,利用瞬态平面源技术,在不同NP浓度下,对Fe3O4@PAA和Al2O3 NFs的导热系数进行了测量。结果表明,Fe3O4@PAA纳米颗粒的导热系数高于Al2O3纳米颗粒。然而,在整个NP浓度测试范围内,Al2O3 NF的导热系数随NP浓度的增加呈线性增强,而Fe3O4@PAA NF的导热系数则有两种不同的情况。
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引用次数: 1
Silicon Carbide for Advanced In-Vivo Medical Devices 先进体内医疗设备用碳化硅
S. Saddow
Silicon Carbide (SiC) is a highly versatile semiconductor material that has long been used in harsh applications such as space, corrosive and high-temperature environments and, more recently, the human body. The impressive and highly advantageous materials properties of SiC have shown that this material is ideally suited for medical applications due to its proven bio- and hemocompatibility. Indeed, SiC appears to be quite unique for use in the human brain whereby implants made using SiC coatings have demonstrated vastly improved performance with virtually no human body immune response which plagues Silicon technology. After over two decades of focused research and development SiC is now ready for use in the healthcare sector and this paper provides an up to date assessment of SiC devices for long-term human use. First the plethora of applications that SiC is uniquely positioned for in human healthcare is reviewed so that healthcare professionals will be fully aware of the significant opportunities now possible with the rapid development of this technology. Next progress in two areas will be presented: Neural implants and deep-tissue cancer therapy using SiC nanotechnology.
碳化硅(SiC)是一种高度通用的半导体材料,长期以来一直用于苛刻的应用,如空间,腐蚀性和高温环境,以及最近的人体。SiC令人印象深刻且非常有利的材料特性表明,由于其经过验证的生物和血液相容性,这种材料非常适合医疗应用。事实上,SiC在人脑中的应用似乎是非常独特的,使用SiC涂层制成的植入物已经显示出大大提高了性能,几乎没有人体免疫反应,这困扰着硅技术。经过二十多年的重点研究和开发,SiC现已准备好在医疗保健部门使用,本文提供了用于长期人类使用的SiC器件的最新评估。首先,我们回顾了SiC在人类医疗保健领域的众多独特应用,以便医疗保健专业人员充分认识到随着这项技术的快速发展,现在可能存在的重大机遇。接下来将介绍两个领域的进展:神经植入和使用碳化硅纳米技术治疗深部组织癌症。
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引用次数: 0
Dynamic characterization of biosensing MEMS cantilevers with different position of the driving electrode - vacuum response versus ambient conditions 不同驱动电极位置的生物传感MEMS悬臂梁动态特性-真空响应与环境条件
M. Pustan, C. Bîrleanu, F. Șerdean
The influence of the driving electrode positions on the dynamic response of polysilicon MEMS resonators used in biosensing applications is studied as a function of the operating conditions (vacuum versus free-air operating mode). The scope of this research work is orientated to identify the effect of driving electrode position on the dynamic response of sensing MEMS used in bio-mass detection. The mass-deposition detection is based on the change in the resonant frequency of vibrating elements considering a biological detection film deposited on the oscillating structure. The operating conditions, such as medium pressure, change the behavior of the dynamic response including the resonant frequency, the amplitude, and the velocity of oscillations as well as the quality factor and the loss of energy. The change in the dynamic response of the investigated MEMS cantilevers as function of the lower electrode position and operating conditions is evaluated using a Polytec Laser Vibrometer. The decrease in the amplitude and velocity of the oscillations if the lower electrode is moved from the beam free-end toward the beam anchor is experimentally monitored. The changes in the response of samples in vacuum are slightly influenced by the electrode position compared with the response of the same sample in ambient conditions. Moreover, the effect of oscillating modes (1st, 2nd and 3rd modes) is taken into consideration to improve the dynamical detection of the investigated samples. The obtained results indicate that, different responses of MEMS resonators can be achieved if the position of the driving electrode is moved from the cantilever free-end toward the anchor. Indeed, the resonator stiffness, velocity and amplitude of oscillations are significantly modified for samples oscillating in ambient conditions for biological detection compared with their response in vacuum.
研究了驱动电极位置对用于生物传感的多晶硅MEMS谐振器动态响应的影响,并将其作为工作条件(真空与自由空气工作模式)的函数。本研究的范围是确定驱动电极位置对用于生物质量检测的传感MEMS动态响应的影响。质量沉积检测是基于振动元件谐振频率的变化,考虑沉积在振荡结构上的生物检测膜。工作条件,如介质压力,会改变动态响应的行为,包括谐振频率、振幅和振荡速度,以及质量因子和能量损失。利用Polytec激光测振仪对所研究的MEMS悬臂梁的动态响应随下电极位置和工作条件的变化进行了评估。实验监测了下电极从梁自由端向梁锚移动时振荡幅度和速度的减小。样品在真空条件下的响应变化受电极位置的影响较小,而相同样品在环境条件下的响应变化受电极位置的影响较小。此外,还考虑了振动模态(一、二、三模态)的影响,以提高所研究样品的动态检测能力。结果表明,当驱动电极的位置从悬臂自由端向锚点移动时,MEMS谐振器的响应会有所不同。实际上,与在真空条件下的响应相比,在生物检测环境条件下振荡的样品的谐振腔刚度、速度和振荡幅度都有显著的改变。
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引用次数: 0
Droplet formation in a cross-junction microfluidic channel with non-Newtonian dispersed phase 具有非牛顿分散相的交叉结微流控通道中液滴的形成
Maryam Fatehifar, A. Revell, M. Jabbari
Microfluidics enables generating series of isolated droplets for high-throughput screening. As many biological/chemical solutions are of shear thinning non-Newtonian nature, we studied non-Newtonian droplet generation to improve the reliability of simulation results in real-life assays. We considered non-Newtonian power-law behaviour for Xanthan gum aqueous solution as the dispersed phase, and Newtonian canola oil as the continuous phase. Simulations were performed in OpenFOAM, using the inter foam solver and volume of fluid (VOF) method. A cross-junction geometry with each inlet and outlet channel height (H) and width (W) equal to 50 micrometers with slight contractions in the conjunctions was used to gain a better monodispersity. Following validation of the numerical setup, we conducted a series of tests to provide novel insight into this configuration. With a capillary number, of 0.01, dispersed phase to continuous phase flow-rate ratio of 0.05, and contact angle of 160°, simulations revealed that, by increasing the Xanthan gum concentration (0, 800, 1500, 2500 ppm) or, in other words, decreasing the n-flow behaviour index from 1 to 0.491, 0.389, and 0.302 in power-law model, (a) breakup of the dispersed phase thread occurred at 0.0365, 0.0430, 0.0440, and 0.0450 s; (b) the dimensionless width of the thread at the main channel entrance increased from 0 to 0.066, 0.096, and 0.16; and (c) the dimensionless droplet diameter decreased from 0.76 to 0.72, 0.68, and 0.67, respectively. Our next plan is to study effect of shear-thinning behaviour on droplet generation in different Ca and flow-rate ratios.
微流体技术能够产生一系列孤立的液滴,用于高通量筛选。由于许多生物/化学溶液具有剪切变薄的非牛顿性质,我们研究了非牛顿液滴的产生,以提高实际分析中模拟结果的可靠性。我们考虑黄原胶水溶液的非牛顿幂律行为作为分散相,牛顿菜籽油作为连续相。在OpenFOAM中使用泡沫间求解器和流体体积(VOF)法进行了模拟。为了获得更好的单分散性,采用了交叉结的几何结构,每个入口和出口通道的高度(H)和宽度(W)均为50微米,连接处有轻微的收缩。在数值设置验证之后,我们进行了一系列测试,以提供对该配置的新见解。在毛细管数为0.01、分散相与连续相流量比为0.05、接触角为160°的条件下,通过增加黄原胶浓度(0、800、1500、2500 ppm)或将幂律模型中的n-流动行为指数从1降低到0.491、0.389和0.302,(a)分散相螺纹在0.0365、0.0430、0.0440和0.0450 s发生断裂;(b)主通道入口螺纹的无因次宽度由0增加到0.066、0.096和0.16;(c)无量纲液滴直径分别从0.76减小到0.72、0.68和0.67。我们的下一步计划是研究剪切减薄行为对不同Ca和流量比下液滴生成的影响。
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引用次数: 1
Magnetically actuated glaucoma drainage device with adjustable flow properties after implantation 磁致青光眼引流装置,植入后流量特性可调
Inês C. F. Pereira, H. Wyss, H. Beckers, J. Toonder
Glaucoma is the second leading cause of preventable blindness worldwide, following cataract formation. A rise in the intraocular pressure (IOP) is a major risk factor for this disease, and results from an elevated resistance to aqueous humor outflow from the anterior chamber of the eye. Glaucoma drainage devices provide an alternative pathway through which the aqueous humor can effectively exit the eye, thereby lowering the IOP. However, post-operative IOP is unpredictable and current implants are deficient in maintaining IOP at optimal levels. To address this deficiency, we are developing an innovative, non-invasive magnetically actuated glaucoma implant with a hydrodynamic resistance that can be adjusted following surgery. This adjustment is achieved by integrating a magnetically actuated microvalve into the implant, which can open or close fluidic channels using an external magnetic stimulus. This microvalve was fabricated from poly(styrene–block–isobutylene–block–styrene), or ‘SIBS’, containing homogeneously dispersed magnetic microparticles. “Micro-pencil” valves of this material were fabricated using a combination of femtosecond laser machining with hot embossing. The glaucoma implant is comprised of a drainage tube and a housing element fabricated from two thermally bonded SIBS layers with the microvalve positioned in between. Microfluidic experiments involving actuating the magnetic micro-pencil with a moving external magnet confirmed the valving function. A pressure difference of around 6 mmHg was achieved, which is sufficient to overcome hypotony (i.e., too low IOP)—one of the most common post-operative complications following glaucoma surgery.
青光眼是仅次于白内障的全球第二大可预防失明原因。眼内压(IOP)升高是本病的主要危险因素,其原因是对眼前房房水流出的抵抗力升高。青光眼引流装置提供了另一种途径,通过该途径房水可以有效地流出眼睛,从而降低IOP。然而,术后IOP是不可预测的,目前的植入物在维持最佳IOP水平方面存在缺陷。为了解决这一缺陷,我们正在开发一种创新的、无创的磁驱动青光眼植入物,该植入物具有水动力阻力,可以在手术后进行调整。这种调整是通过将一个磁致动微阀集成到植入物中来实现的,该微阀可以使用外部磁刺激打开或关闭流体通道。这种微阀是由含有均匀分散的磁性微粒的聚苯乙烯块-异丁烯块-苯乙烯块(SIBS)制成的。采用飞秒激光加工和热压加工相结合的方法制造了这种材料的“微型铅笔”阀。青光眼植入物由引流管和由两个热粘合SIBS层制成的外壳元件组成,微阀位于两者之间。用移动的外磁铁驱动磁性微铅笔的微流控实验证实了阀的功能。眼压差约为6 mmHg,足以克服低眼压(即IOP过低),这是青光眼手术后最常见的术后并发症之一。
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引用次数: 0
Development of Gelatin-Based Flexible Three-Dimensional Capillary Pattern Microfabrication Technology for Analysis of Collective Cell Migration 基于明胶的柔性三维毛细管模式微加工技术在细胞集体迁移分析中的应用
Hiromichi Hashimoto, Mitsuru Sentoku, Kento Iida, K. Yasuda
The collective cell migration is thought to be a dynamic and interactive behavior of cell cohorts which is essential for diverse physiological developments in living organisms. Recent studies revealed that topographical properties of the environment regulate the migration modes of cell cohorts, such as diffusion versus contraction relaxation transport and the appearance of vortices in larger available space. However, conventional in vitro assays fail to observe the change in cells behavior in response to the structural changes. Here, we have developed a method to fabricate the flexible three-dimensional structures of capillary microtunnels to examine the behavior of vascular endothelial cells (ECs). The microtunnels with altering diameters were formed inside gelatin-gel by spot heating a portion of gelatin by irradiating the µm-sized absorption at the tip of the microneedle with a focused permeable 1064 nm infrared laser. The ECs moved and spread two-dimensionally on the inner surface of capillary microtunnels as monolayer instead of filling the capillary. In contrast to the 3D straight topographical constraint, which exhibited width dependence migration velocity, leading ECs altered its migration velocity accordingly to the change in supply of the cells behind the leading ECs, caused by the progression through the diameter altering structure. Our findings provide insights into the collective migration properties in 3D confinement structures as fluid-like behavior with conservation of cell numbers.
细胞集体迁移被认为是细胞群的动态和相互作用行为,是生物体多种生理发育所必需的。最近的研究表明,环境的地形特性调节着细胞群的迁移模式,如扩散与收缩弛豫运输以及在更大的可用空间中出现的漩涡。然而,常规的体外实验无法观察到细胞行为随结构变化的变化。在这里,我们开发了一种方法来制造毛细血管微隧道的柔性三维结构来检测血管内皮细胞(ECs)的行为。通过聚焦1064 nm可渗透红外激光照射微针尖端µm大小的吸收区,对部分明胶进行点加热,在明胶内部形成直径变化的微隧道。内皮细胞在毛细血管微隧道内表面呈单层二维移动和扩散,而不是填充毛细血管。与3D直线地形约束表现出宽度依赖的迁移速度不同,前导ECs的迁移速度随着前导ECs后面的细胞供应的变化而变化,这是由直径改变结构的进展引起的。我们的发现为三维约束结构中的集体迁移特性提供了见解,这些特性具有细胞数量守恒的流体样行为。
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引用次数: 0
Elasto-Magnetic Pumps Integrated within Microfluidic Devices 集成在微流体装置中的弹性磁泵
Jacob L. Binsley, E. L. Martin, Thomas O Myers, S. Pagliara, F. Ogrin
Many lab-on-a-chip devices require a connection to an external pumping system in order to perform their function. While this is not problematic in typical laboratory environments, it is not always practical when applied to point-of-care testing, which is best utilised outside of the laboratory. Therefore, there has been a large amount of ongoing research into producing integrated microfluidic components capable of generating effective fluid flow from on-board the device. This research aims to introduce a system which can produce practical flow rates, and be easily fabricated and actuated using readily available techniques and materials. We show how an asymmetric elasto-magnetic system, inspired by Purcell’s 3-link swimmer can provide this solution through the generation of non-reciprocal motion in an enclosed environment. The device is fabricated monolithically within a microfluidic channel at the time of manufacture, and is actuated using a weak, oscillating magnetic field. The flow rate can be altered dynamically, and the resultant flow direction can be reversed by adjusting the frequency of the driving field. The device is proven, experimentally and numerically, to operate effectively when applied to fluids with a range of viscosities. Such a device may be able to replace external pumping systems in more portable applications.
许多芯片实验室设备需要连接到外部泵送系统才能执行其功能。虽然这在典型的实验室环境中没有问题,但当应用于护理点检测时,它并不总是实用的,它最好在实验室之外使用。因此,人们正在进行大量的研究,以生产能够从机载设备产生有效流体流动的集成微流体组件。本研究旨在介绍一种可以产生实际流量的系统,并且可以使用现成的技术和材料轻松制造和驱动。我们展示了受Purcell的3链游泳器启发的不对称弹磁系统如何通过在封闭环境中产生非互反运动来提供这种解决方案。该装置在制造时在微流体通道内单片制造,并使用弱振荡磁场驱动。通过调节驱动场的频率,可以动态地改变流量,并改变最终的流动方向。实验和数值证明,该装置在应用于粘度范围内的流体时有效运行。这种装置可以在更便携的应用中取代外部泵系统。
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引用次数: 0
Rotating Micromachines with Stratified Disk Architecture for Dynamic Bioanalysis 用于动态生物分析的具有分层磁盘结构的旋转微机器
Gungun Lin, Yuan Liu, Guan Huang, Yinghui Chen, D. Makarov, D. Jin
Magnetic microrobots with versatile mechanical motion will enable many ex- and in vivo applications. Unfortunately, monolithic integration of multiple functions in a streamlined microrobotic body is still challenging due to the compromise between fabrication throughput, device footprints, and material choices. In this talk, I will present a unified framework architecture for microrobotic functionalization to enable magnetically steered locomotion, chemical sensing and in vivo tracking. This has been achieved through stratifying stimuli-responsive nanoparticles in a hydrogelmicro-disk. We uncovered the key mechanism of leveraging spatially alternating magnetic energy potential to control a Euler’s disk-like microrobot to locomote swiftly on its sidewall. The results suggest great potential for microrobots to locomote while cooperating a wide range of functions, tailorable for universal application scenarios.
具有多用途机械运动的磁性微型机器人将使许多体外和体内应用成为可能。不幸的是,由于制造吞吐量、器件占地面积和材料选择之间的折衷,在流线型微型机器人体内集成多种功能仍然具有挑战性。在这次演讲中,我将介绍一个用于微机器人功能化的统一框架架构,以实现磁操纵运动,化学传感和体内跟踪。这是通过在水凝胶微盘中分层刺激响应纳米颗粒来实现的。我们揭示了利用空间交变磁能势来控制欧拉圆盘状微型机器人在其侧壁上快速移动的关键机制。结果表明,微型机器人在移动的同时具有广泛的功能,适合通用应用场景,具有很大的潜力。
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引用次数: 0
Materials, Methods, and Optimized Designs for Soft Wearable Electronics with Significantly Reduced Motion Artifacts 具有显著减少运动伪影的软性可穿戴电子产品的材料、方法和优化设计
W. Yeo, Nathan Rodeheaver
Wearable electronics are changing healthcare and increasing possibilities for human-machine interfaces. Soft electronics, directly mounted on the skin, can monitor long-term heart rate trends or direct smart prosthetics' motion. However, these capabilities are only as good as the signal quality obtained. These wearable devices are worn in the real world, often suffering from motion artifacts not previously found when measured in a stationary setting such as a clinic or laboratory. Motion artifacts can mimic many biosignals by having a similar amplitude and frequency range, making them hard to filter out. A significant source of motion artifacts is from relative motion between the sensor and the signal source. Given human tissue's elastic nature, most body-mounted sensors undergo more relative motion than on a comparable rigid machine. Here, this work introduces a comprehensive study of materials, methods, and optimized designs that can significantly reduce motion artifacts via strain isolation, increased adhesion, and enhanced breathability for long-term recordings. Skin strain is another source of motion artifacts that can disturb electrodes' contact impedance and temporarily change the biopotential within the skin. We present a prototype electrocardiogram (ECG) device that uses a strain isolating layer to reduce skin strain at the electrode. This strategic integration of soft and hard materials reduces motion artifacts by stabilizing the electrode, while allowing freedom of movement elsewhere to maintain gentle contact with the skin. These solutions are demonstrated for long-term ECG collection but have application for any skin-mounted wearable device.
可穿戴电子设备正在改变医疗保健,并增加人机界面的可能性。直接安装在皮肤上的软电子设备可以监测长期心率趋势或指导智能假肢的运动。然而,这些能力仅与获得的信号质量一样好。这些可穿戴设备是在现实世界中佩戴的,通常会出现以前在诊所或实验室等固定环境中测量时没有发现的运动伪影。运动伪影可以模仿许多生物信号,因为它们具有相似的幅度和频率范围,这使得它们很难被过滤掉。运动伪影的一个重要来源是传感器和信号源之间的相对运动。考虑到人体组织的弹性,大多数安装在身体上的传感器比类似的刚性机器承受更多的相对运动。在这里,这项工作介绍了材料,方法和优化设计的综合研究,可以通过应变隔离,增加附着力和增强长期记录的透气性来显着减少运动伪影。皮肤张力是运动伪影的另一个来源,它会干扰电极的接触阻抗,并暂时改变皮肤内的生物电势。我们提出了一种原型心电图(ECG)装置,该装置使用应变隔离层来减少电极处的皮肤应变。这种软硬材料的战略性整合通过稳定电极来减少运动伪像,同时允许在其他地方自由运动,以保持与皮肤的温和接触。这些解决方案用于长期ECG采集,但适用于任何皮肤安装的可穿戴设备。
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引用次数: 0
Misconceptions in Piezoelectric Energy Harvesting System Development 压电能量收集系统开发中的误区
K. Uchino
Energy harvesting from wasted or unused power has been a topic of discussion for a long time. We developed ‘damper devices’ for precision machinery and automobile engine mats in the 1980s. However, in the 1990s we realized that electric energy dissipation on its own was useless, and started to accumulate the converted electric energy into a rechargeable battery. Historically, this was the starting point of ‘piezoelectric energy harvesting devices’.
从浪费或未使用的电力中获取能量一直是人们讨论的一个话题。我们在20世纪80年代为精密机械和汽车发动机垫开发了“阻尼装置”。然而,在20世纪90年代,我们意识到电能本身的耗散是无用的,并开始将转换后的电能积累成可充电电池。从历史上看,这是“压电能量收集装置”的起点。
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引用次数: 2
期刊
Proceedings of Micromachines 2021 — 1st International Conference on Micromachines and Applications (ICMA2021)
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