高通量小间距细胞电穿孔装置设计及实验测试

细胞电穿孔技术是指通过施加一定的电场强度可逆地击穿细胞膜,在细胞膜上形成小孔或 通路,从而使遗传物质引入细胞内。传统的细胞电穿孔装置往往需要几百伏到几千伏的电压,操作 十分危险。该研究采用电绝缘的聚氯乙烯(PVC)薄膜,制作了一种电极间距为 80 μm 的小间距电穿 孔装置,并且可以进行高通量操作。经测试,所提出的小间距电穿孔装置实现细胞电穿孔所需的电 压比 1 mm 标准电击杯降低了一个数量级,极大地提高了实验操作的安全性。高通量操作也极大地 提高了实验效率,但由于电穿孔转化效率比 1 mm 标准电击杯低了一个数量级,因此实验参数需要 进一步优化。     

基于同步测量的电阻抗层析成像系统研究

针对APT模式EIT系统存在的异步测量、结构复杂、调试困难等问题,研究设计了一种基于同步测量的电阻抗层析成像系统,从硬件和软件两个方面阐述了如何实现同步测量.系统硬件由PXI集成控制器、开关模块、数据采集模块和自制电流源组成,简化了系统结构,提高了系统的稳定性和精确度.本系统采用LabVIEW开发了专用软件包,实现了信号的同步采集,并用改进正则化算法重建了电导率分布图像.对比实验显示了同步测量和异步测量的差异,结果表明同步测量EIT系统图像更清晰,伪影更少,平均相对误差降低了48.99%.本文提供了一种可行的EIT系统同步测量方法,该方法适用于多电极(电极数≥16)场域的无损伤成像应用.     

一种基于感光干膜-铟锡氧化物电极的简易细胞阻抗传感器实现细胞形态学和阻抗信息同时检测

加工一种基于感光干膜-铟锡氧化物DFP-ITO( Dry Film Photoresist-Indium Tin Oxide)电极的细胞阻抗生物传感器并实现细胞形态学和阻抗信息同时检测。35μm厚的感光干膜层压在ITO导电玻璃表面上作为绝缘层,通过照相制版技术在感光干膜绝缘层上蚀刻不同直径圆孔;以DFP-ITO作为工作电极,通过夹具和测量小池与Ag/AgCl参比电极、Pt丝对电极相连构成三电极阻抗测量系统;考察了不同直径DFP-ITO工作电极阻抗谱特征;通过细胞粘附实验及细胞毒性实验考察了感光干膜细胞生物相容性;通过光学显微镜和阻抗谱技术分别对接种在DFP-ITO电极上人肺癌细胞株A549粘附、增殖过程中的形
　　态学和阻抗信息进行检测和分析。研究结果发现不同直径DFP-ITO电极具有相似的阻抗特性;充分固化的感光干膜表面适宜A549细胞粘附且无明显的细胞毒性;基于DFP-ITO电极构建的细胞阻抗传感器能够通过光学显微镜获取A549细胞形态学数据,同时通过阻抗谱技术能够解析A549细胞粘附、增殖过程中的细胞质膜电容、细胞-细胞间隙电阻、细胞-ITO电极间隙电阻变化。本文发展了基于DEP-ITO电极的细胞阻抗传感器结构简单,可实现细胞形态学和阻抗信息的双通道获取,未来可用于细胞生理病理学行为和药物细胞毒性研究。     

用于评估皮肤渗透能力的无创皮肤阻抗测量系统

设计了基于AD5933的无创皮肤阻抗测量系统,用来评估皮肤渗透能力,提高经皮给药、提取组织液目标物的效率。系统利用二电极比例法,并采用时钟频率切换、量程自动切换和软件校准补偿等技术,实现了对低频皮肤阻抗的测量。基于电穿孔法进行促渗透处理前后的皮肤对系统进行了阻抗测量实验验证。结果表明:该系统可用于对皮肤渗透性的表征,可给人体生理生化检测相关的可穿戴设备参数调节提供依据。     

湿度对微型加速度计粘连失效的影响

粘连是微/纳器件的一种典型失效模式,由于湿度引起的粘连失效占很大比例。以MEMS摆式加速度计为模型,分析了湿度引起粘连失效的机理,主要是毛细黏性力的影响。为了研究材料性质和粗糙度对粘连的影响,对比钨(W)、铝铜(AlCu)和铝(Al)3种不同电极材料,发现Al电极材料表面接触角和表面粗糙度都很大,对应芯片的粘连比例较少。利用HMDS对粘连芯片内表面进行疏水处理,有效减少了粘连比例。研究表明选用接触角大的电极材料、增加电极表面粗糙度和表面疏水处理均能有效减少毛细黏性力为主导的粘连。     

基于柔性电极的便携式心电监测系统研究

针对普通干电极和医用湿电极应用于心电监测系统时存在的问题,制备了 一种聚二甲基硅氧烷(polydimethylsiloxane,PDMS)基底上阵列金字塔结构的柔性电极.该电极通过阵列金字塔结构加大电极表面积,减小电极阻抗,并对心电信号处理电路、基于安卓端的APP等部分进行了设计,制作了便携式心电监测系统.实验结果表明...     

介体化学修饰电流型生物传感器

生物传感器作为生物化学和微电子学相结合的产物,是一种独特的联合体,它是由固定化酶,细胞或其它生物活性物质与换能器(如电极、离子敏场效应管、光导纤维和光二极管、热敏电阻和压电晶体等)密切结合的分析系统,以生化信号转化为电信号测定许多物质。鉴于酶具有识别特定分子的能力,Clark等人于1962年首先提出了酶与电极结合起来的原理,从而开拓了一个新的生物传感器的领域,该电极是基于下列催化反应。     

基于声表面波技术的微流体混合及仿真

报道了在微流系统中使用基于叉指聚焦换能器的声表面波的一种有效方法.利用lift-off和软光刻技术在铌酸锂( LiNbO3)压电单晶片基底上制作器件.使用有限元分析软件COMSOL Multiphysics分别模拟聚焦叉指电极和平行叉指电极两种声表面波的形成和分布.通过与相同条件下的平行叉指电极比较,说明聚焦叉指电极可...     

苯硼酸修饰的聚乙烯亚胺系统在 T 细胞小 RNA 转染的应用

小 RNA 是 T 细胞发育、分化和功能的重要调控分子，但目前仍缺乏安全有效的 T 细胞 RNA 转 染系统。基于 T 细胞表面唾液酸化的特性，该文利用苯硼酸和唾液酸的相互作用，带动苯硼酸修饰的聚乙烯亚胺系统(Polyethylenimine-Phenylboronic Acid，PEI-PBA)介导小 RNA 的 T 细胞转染。通过细胞计数试剂盒(CCK-8)和羟基荧光素二醋酸盐琥珀酰亚胺脂(CFSE)实验显示，PEI-PBA 转染系统对 T 细胞无显著细胞毒性和异常增殖。同时，流式检测人源抗 CD3/28 磁珠激活下的分化抗原 3(CD3)阳性 T 细胞在 PEI-PBA 转染系统下，小 RNA 平均摄取率增加到18.43%，而在鼠源 T 细胞中 PEI-PBA 介导的小 RNA 转染并无明显效果。结果显示，PEI-PBA 纳米转染系统介导小 RNA 的递送具有无毒高效的特点。     

基于片段合并的胚胎电子细胞基因压缩方法

针对胚胎电子细胞中基因存储硬件消耗较大的问题,提出了一种基于基因片段合并的胚胎电子细胞基因压缩编码方法。在编码过程中,把问题转化为图着色问题,采用遗传算法对基因中的填充位(X位)进行兼容赋值,从而把基因片段合并为基本兼容基因片段,实现基因压缩。利用概率论的知识对采用基因压缩方法实现基因存储的新型胚胎电子细胞结构的硬件消耗进行了理论分析。以实际电路作为目标电路进行仿真,结果表明,上述方法能有效地降低基因存储的硬件消耗。     

A novel method to construct 3D electrodes at the sidewall of microfluidic channel

We report a simple, low-cost and novel method for constructing three-dimensional (3D) microelectrodes in microfluidic system by utilizing low melting point metal alloy. Three-dimensional electrodes have unique properties in application of cell lysis, electro-osmosis, electroporation and dielectrophoresis. The fabrication process involves conventional photolithography and sputtering techniques to fabricate planar electrodes, positioning bismuth (Bi) alloy microspheres at the sidewall of PDMS channel, plasma bonding and low temperature annealing to improve electrical connection between metal microspheres and planar electrodes. Compared to other fabrication methods for 3D electrodes, the presented one does not require rigorous experimental conditions, cumbersome processes and expensive equipments. Numerical analysis on electric field distribution with different electrode configurations was presented to verify the unique field distribution of arc-shaped electrodes. The application of 3D electrode configuration with high-conductive alloy microspheres was confirmed by particle manipulation based on dielectrophoresis. The proposed technique offers alternatives to construct 3D electrodes from 2D electrodes. More importantly, the simplicity of the fabrication process provides easy ways to fabricate electrodes fast with arc-shaped geometry at the sidewall of microchannel.     

Somatic and stem cell pairing and fusion using a microfluidic array device

There is considerable excitement about the prospect of tissue repair and renewal through cell replacement therapies. Nonetheless, many of these techniques may require the reprogramming of somatic and stem cells through cell fusion. Previous fusion methods often suffer from random cell contacts, poor fusion yields, or complexity of design. We have developed a simplified cell-electrofusion chip that possesses a dense microelectrode array, which enables the simultaneous pairing and electrofusion of thousands of cells by manipulation dielectrophoretic force and electroporation. Human embryonic kidney 293 (HEK293) cells, mouse fibroblasts (NIH3T3 cells), and mouse embryonic stem cells were arranged for cell fusion with the same and mixed cell type. The pairing efficiency for a 2-cell alignment of mixed cells was ~35%, and a fusion efficiency of ~46% in cell pairs was achieved. Significant cell death occurs with fusion voltages ?? 10 V, and electrofusion with our chip was achieved on a ~1000 V cm^?1 electric field strength induced by a low intensity voltages (9 V). Therefore, the chip used in this study provides a simple, low voltage alternative with sufficient throughput for hybrid cell experiments and somatic cell reprogramming research.     

A 513‐ppi FFS‐mode LCD using technique for changing part of active layer of oxide semiconductor to transparent electrode

We have established a technique for changing part of an active layer of an oxide semiconductor (OS) to a transparent electrode in order to achieve an aperture ratio of 50% or higher and a bezel width of 1 mm in an fringe field switching (FFS) mode LCD panel with a high resolution of 513 ppi. Furthermore, we have prototyped an LCD panel by examining a driving mode that enables low‐frequency driving.     

Measurement of local electric field in microdevices for low-voltage electroporation of adherent cells

In this study, we present the measurement of the local electric field in a microdevice designed for electroporation of adherent cells. The microdevice mainly consists of a coverslip that has a transparent conductive layer and an insulating layer. The insulating layer has small cylindrical holes that focus the field lines to reduce the voltage required for electroporation. We estimated the local electric field at the cells by analyzing the ionic current based on a simple equivalent circuit model and investigated the correlation between the field strength and the efficiency of electroporation. We prepared various designs with matrices of electrodes with diameters ranging from 5 to 10 μm and center-to-center distances between adjacent electrodes ranging from 20 to 75 μm to perform systematic and statistical investigations. Furthermore, we discussed the efficiency of the electrode design in terms of the degree of field focusing, the applicability of optical observations, and the probability of positioning cells on the electrodes.     

可控硅-感应电机型电极升降自动控制系统

本文介绍了一种以相轨迹法为基础的电极升降启动控制系统(简称KZJ系统),求出了便 于应用的相轨迹转换曲线,使一些用频率法无法研究的现象皆能用相轨迹进行研究.同时给 出了系统特点、电机的最佳运行方式及系统各环节参数的整定方法.     

Microfabricated electrochemical sensors for exhaustive coulometry applications

The development of microfabricated electrochemical systems suitable for deployment in sensor networks that operate with a minimum of operator intervention are of great interest; therefore, a coulometric sensing system for exhaustive coulometry with the potential for calibration-free operation has been designed, fabricated and evaluated to support such development. The sensor chips were microfabricated onto a silicon substrate and contained a variety of specially designed thin-film gold working electrodes (ranging from one to five per chip) and a Ag/AgCl pseudo-reference electrode. A custom flow cell containing fluidic connections and counter electrode chamber was also constructed to integrate the sensor and to create an electrolysis chamber with a fixed volume. Different chip designs were evaluated as exhaustive coulometric sensors in terms of reproducibility and longevity using Fe(CN)₆^3?/4? as model analytes. The relative standard deviation (RSD) for a chip tested over a period of 42 days was 5.5% whereas the sensor-to-sensor reproducibility was within 6.3%.     

Viewing angle switchable blue‐phase liquid crystal display with low voltage and high transmittance

We propose a viewing angle switchable blue‐phase liquid crystal display with low voltage and high transmittance. In this device, in‐plane protrusions are used to lower operating voltage and improve the transmittance. Besides, the top electrode can control viewing angle of the proposed display. When no voltage is applied to the top electrode, the display shows wide viewing angle mode. On the contrary, this display shows narrow viewing angle mode. So, this device exhibits low operating voltage, high transmittance, and good viewing angle controllable characteristics.     

Microfluidics cell electroporation

Electroporation or electropermeabilization is one of the most powerful biological techniques in cell studies. Applying the high voltage electric field in vicinity of the cells can generate nanopores in cell membrane. Varying with the intensity and the duration of these applied electric field, the created nanopores can be temporary (reversible electroporation) or permanent (irreversible electroporation). Reversible electroporation is usually conducted to insert biological samples into the cells. Cells are also electroporated irreversibly to release their intercellular contents for further biological investigations. In comparison with the conventional electroporation devices, microfluidic (microscale) electroporation devices have some advantages such as higher cell viability rate, high transfection efficiency, lower sample contamination, and smaller Joule heating effect. In this article, the latest advancement in microfluidic cell electroporation is reviewed. First, the underlying theory of membrane permeabilization is reviewed and the leading analytical studies on the cell electroporation are presented. Following that, different experimental methods are compared. Finally, some suggestions are proposed for the future studies.     

Output-oriented power saving mode for mobile devices

Fast battery discharge is still the most nerve wracking issue for smartphone users. Though many energy saving methods have been studied, still users are not satisfied with their phone’s battery. Power management system provides low power mode when the phone is not in use for a long time. When the user is interacting with the phone, current system assumes the user is interactive and should keep the device in active mode. However, this is not true. After the user’s interaction, the device processes the request and displays the result on the smartphone’s output device. During this period, the user cannot see any meaningful information from the phone. In this paper, we propose a new low power mode where we put smartphone’s output device into low power mode while phone is preparing result for the user. We named this as o-sleep, an output-oriented power saving mode. While a device is processing a user’s request, output from the device may require preparation time. We consider the situation as the device’s output idle time and put the phone’s user interfaces into sleep mode while maintaining other subsystems in active state. To prove our concept, we have applied our technique onto various smartphone applications with varying operation environment. From the experiment, we found that the smartphone entered the o-sleep mode up to 58% of its total usage time in various test scenarios. Usability study supported feasibility of our proposed method.     

Fabrication of a stainless steel shadow mask using batch mode micro-EDM

A metal shadow mask for organic thin-film transistors (OTFTs) has been fabricated by batch mode electro-discharge machining (EDM). Batch mode micro-electro-discharge machining method was applied for productivity improvement. Negative electrode with multiple holes (3 × 3 or 4 × 4) was fabricated using a single tool electrode. With the negative electrode, 3 × 3 and 4 × 4 tool electrode arrays are EDMed; 6 × 6 and 16 × 16 square hole array masks were batch mode EDMed with the fabricated multi-electrodes arrays. With 4 × 4 electrode array, the productivity is improved to five times of that in the case using a single electrode. Source and drain electrodes of OTFTs were successfully patterned on a pentacene active layer through the mask, and the fabricated pentacene TFTs had good output characteristics.