不同尺寸参数对双极高频电刀热应力场的影响

目的分析不同尺寸参数对双极高频电刀热应力场的影响规律。方法基于有限元分析软件ANSYS,对双极高频电刀工作过程中的热应力场进行系统的电热耦合仿真分析,研究3种不同绝缘层厚度(0.5、1.0、1.5 mm)、电极厚度(0.5、1.0、1.5 mm)以及涂层厚度(3、6、9μm)对高频电刀各部分热应力场的影响。结果绝缘层厚度越大,心肌组织由于热应力产生的变形量越小,即高频电刀工作过程中绝缘层厚度与心肌组织的热变形量成反比;对于3种电极厚度而言,选取1.0 mm更为合适;对于3种涂层厚度而言,选取6μm更为合适。结论高频电刀各组成部件的尺寸参数对其工作过程中的热应力场有重要的影响,研究结果可为高频电刀的设计开发提供指导。     

腹腔镜手术悬吊系统的设计与仿真分析

目的 基于现有的气腹装置,在低气压的前提下,设计一款用于微创手术的新型悬吊系统,以暴露更多手术视野,便于手术顺利进行。方法 利用Solidworks软件完成悬吊系统的结构设计,并基于有限元仿真分析技术,研究医用不锈钢、钛合金Ti6Al4V、钛合金Ti6Al7Nb和纯钛4种不同夹子制作材料以及尼龙（polyamide 6,PA6）、涤纶、聚丙烯（polypropylene,PP）3种不同中间平面结构制作材料对悬吊系统使用性能的影响。结果 4种不同材料的夹子在夹持组织过程中,组织的形变量均较低,不会出现所夹持组织从夹子中滑脱的现象。就应力而言,选用医用不锈钢材料时,夹子及其夹持组织的应力均最低;对于中间平面结构的制作材料而言,当选取涤纶材料时,在悬吊系统工作过程中,中间平面结构会在外载荷作用下发生破坏;当选用PP材料时,中间平面结构会发生永久变形,且形变量最高,不利于临床手术的进行。结论 选择医用不锈钢作为夹子的制作材料为最佳。不宜选择涤纶作为中间平面结构的制作材料,选择PA6作为中间平面结构的制作材料为最优。     

钨针与不锈钢电极微创电切性能及表面粘附行为研究

该文在高频电刀纯切模式下,分别采用钨针电极和不锈钢电极,切割不同部位新鲜的猪离体组织,使用光学显微镜、红外光谱仪等对组织切割创口表面形貌和电极表面粘附物进行了对比分析。结果表明,微创钨针切割时热损伤更小,切割不同肌体组织,电极表面粘附物不同。     

高频电刀对家兔活体皮肤组织作用的观察

目的：探讨高频电刀和汽化作用对皮肤组织结构的作用。方法：用高频电极在不同输出功率时测定大白家兔活体皮肤组织的电流强度，灼伤中心区汽化深度和汽化表面积，光镜和电镜下观察离创缘0-6mm邻近组织的结构变化。结果：随着电流输出功率的增强，皮肤组织的电流强度，中心区汽化深度和汽化表面积也随之增加，光镜和电镜下电流对不同距离的皮肤组织结构的损伤是不相同的，创缘部位和邻近组织显微和超微结构发生了热凝固性改变，损伤程度随着离中心区距离的延长而减弱，但在4mm邻近处仍有较明显的损伤性改变。结论：用高频电刀操作时应注意对邻近组织的损伤性作用，为减少损伤应严格注意操作时所用的电流强度和对组织的电灼时间。     

高频电刀对家兔活体肌肉组织的作用

目的 :探讨高频电刀对肌肉组织结构的作用。方法 :用高频电极在不同输出功率时测定大白家兔活体肌肉组织的电流强度 ,灼伤中心区汽化深度和汽化表面积 ,光镜和电镜下观察创面下 0～ 6mm深度的组织结构变化。结果 :随着电流输出功率的增强 ,肌肉组织的电流强度 ,中心区汽化深度和汽化表面积也随之增加 ,创面深部组织显微和超微结构发生了热凝固性改变 ,损伤程度随着离中心区距离的延长而减弱 ,但在 6mm深处仍有较明显的损伤性改变。结论 :用高频电刀操作时应注意对深部肌肉组织的损伤性作用 ,为减少损伤应注意操作时的电流强度和电灼时间。     

电汽化对活体肾组织作用的实验研究

目的：探讨电汽化对肾组织结构的作用,为高频电刀和电汽化技术在肾手术中的应用提供实验室依据。方法：用汽化电极在不同输出功率时测定大白家兔活体肾组织的电流强度,灼伤中心区汽化深度和汽化表面积,光镜和电镜下观察0-6mm深度的组织结构变化。结果：随着电流输出功率的增强,肾组织的电流强度,中心区汽化深度和汽化表面积也随之增加,深部组织显微和超微结构发生了凝固性改变,损伤程度随着离中心区距离的延长而减弱。结论：肾手术中用高频电刀应注意对邻近组织的损伤,输出功率不易过大,电汽化技术可尝试应用于肾的手术。     

电极间距与电极直径对恒功率下双极射频熔脂效果影响的研究

在双极射频应用于局部脂肪堆积的无创治疗的过程中,关于双极射频设备的部分设计参数目前还没有形成统一的规范。采用有限元方法和离体实验,分析双极射频熔脂时不同参数对组织熔脂效果的影响,寻求在双极射频尽量不会对皮肤层造成热损伤的同时,实现较大范围熔脂效果的熔脂参数配置。采用COMSOLMultiphysics进行生物组织热电耦合的有限元分析;为验证模型有效性,采用一种自研的单路双极射频输出设备,对离体猪腹部组织进行实验。有限元分析结果显示:经双极射频加热30min后,在功率为10W,电极球直径分别为3、5、8mm,电极间距分别为2和3cm的熔脂参数配置下,皮肤层的最终温度低于热损伤阈值温度,且部分脂肪层在热损伤区域内;域点探针所显示的脂肪层热损伤区域内的温度变化曲线满足熔脂温度要求。不同熔脂参数配置,对双极射频加热下组织内的温度分布具有显著影响。在10W功率下,采用直径为8mm的球型电极,电极按压皮肤的深度为1mm,在电极间距分别为2和3cm的条件下,脂肪层内产生最大面积的连续热损伤区域和点状热损伤区域,热损伤区域的面积分别为2.84和2.55cm²。相同熔脂参数配置的离体实验表明,与组织模型相同位置处的热电偶探针的最终温度和对应的域点探针相差0.92℃±0.43℃。有限元分析结果和实验结果基本一致。由仿真结果和实验结果可知,上述熔脂参数配置可使双极射频不会对皮肤层造成热损伤,同时在脂肪层内产生有效的热损伤区域,并且热损伤区域内的温度达到了熔脂要求。合理的熔脂参数配置是决定双极射频熔脂是否成功的一项关键因素。     

新型射频组织焊接电极的设计、仿真与实验研究

目的 设计一种新型射频组织焊接电极,提高吻合口生物力学强度的同时减少组织热损伤。 方法 设计表面存在镂空结构的新型电极(梅花形电极),以环形电极作为对照组,在射频能量作用下完成肠道组织焊接,通过撕脱力和爆破压测试研究焊接吻合口的生物力学特性,采用有限元电-热-力多场耦合仿真分析和热电偶探针研究焊 接过程中的组织热损伤,并对微观组织结构进行检查。 结果 当焊接功率 120 W、焊接时间 8 s、压合压强 20 kPa时,肠道吻合口呈现最优的生物力学特性。 与环形电极对照组相比,梅花形电极组吻合口生物力学强度更高,撕脱力和爆破压分别从(8. 62±1. 22) N、(81. 7±3. 36) mmHg 增加到 (9. 54±1. 24) N、(89. 4±4. 15) mmHg,且组织热损伤显著减少,组织微观结构连接更为紧密。 结论 该新型电极在提高吻合口生物力学强度的同时可减少组织热损伤,进而实现更好的吻合效果。 研究结果可为实现人体管腔组织的无缝连接提供参考。     

生物组织中与频率有关的电磁能吸收量

一、导论电磁波在生物组织中传播时,两相邻组织(例如肌肉组织/脂肪组织,恶性组织/正常组织)将按单位体积吸收功率(Pa,以W/m~3为单位),其比值为 Pa_2/Pa_1=(?)(1) 式中,σ是组织的电导小数(mho/m),E是组织内的电场强度(V/m),下标表示不同组织。频率在100～500MHz范围内或低于这个范围时,被辐照的组织将处于典型高频加热电极的近端场内。这里用平面波近似值,虽然在高频加热电极近端场内流动的功率部分不是均匀的平面波。对于非侵入性高频加热电极来说,可以预期这种近似对所获得的结果只有很小的影响。     

单回路型负极板在双回路型电刀上的应用及高频电刀使用注意事项的回顾

随着世界各大电刀厂家的不断改进，新型电刀比旧型电刀在回路上也更加科学安全。新型电刀都是使用双回路型负极板，而旧型电刀都是使用单回路型负极板(商品名；中性电极板)，所以旧型单回路负极板无法使用于新型电刀上。一般医院都会有新旧两种电刀在使用的现象，为此医院就要购买两种类型电刀使用的负极板，采购部门因种类多而引起诸多不便，手术室护士因不同电刀使用不同负极板也会增加工作量，双回路负极板比单回路负极板市面价格要高4~5倍，且负极板属于收费的一次性耗材，所以对于县级以下医院的农村患者又增加了一笔经济负担。鉴此笔者将单回路负极板用于双回路电刀上，经临床300例不同性别年龄不同疾病的手术应用，效果良好，观察未出现不良反应和皮肤损伤，介绍如下。     

Radio-frequency lesioning in brain tissue with coagulation-dependent thermal conductivity: modelling,simulation and analysis of parameter influence and interaction

Radio-frequency brain lesioning is a method for reducing e.g. symptoms of movement disorders. A small electrode is used to thermally coagulate malfunctioning tissue. Influence on lesion size from thermal and electric conductivity of the tissue, microvascular perfusion and preset electrode temperature was investigated using a finite-element model. Perfusion was modelled as an increased thermal conductivity in non-coagulated tissue. The parameters were analysed using a 2(4)-factorial design (n=16) and quadratic regression analysis (n=47). Increased thermal conductivity of the tissue increased lesion volume, while increased perfusion decreased it since coagulation creates a thermally insulating layer due to the cessation of blood perfusion. These effects were strengthened with increased preset temperature. The electric conductivity had negligible effect. Simulations were found realistic compared to in vivo experimental lesions.     

大鼠皮肤对驻极体外静电场的影响

目的：研究聚丙烯驻极体透过大鼠皮肤的表面电位衰减情况,探讨大鼠皮肤对驻极体外静电场的影响及静电场对大鼠皮肤的作用机理。为研制优质的驻极体透皮给药贴剂奠定实验基础。方法：利用栅控恒压电晕充电系统将单电极和双裸面聚丙烯薄膜制备成正、负极性的驻极体,借助于等温表面电位衰减测量研究不同极性驻极体透过大鼠皮肤的等效表面电位衰减规律。结果：（1）＋1000V注极的单电极和双裸面聚丙烯驻极体透过大鼠皮肤的表面电位经过48小时保留了其初始值的92．9％和71．3％。（2）-1000V注极的单电极和双裸面聚丙烯驻极体透过大鼠皮肤的表面电位经过48小时后分别衰减了20．7％和18．8％。（3）聚丙烯驻极体透皮电位在72小时内具有和驻极体自身相近的稳定性。结论：（1）单电极和双裸面聚丙烯驻极体均具有优异的电荷储存稳定性。（2）驻极体的表面电位能很好的透过大鼠皮肤．相比双裸面驻极体,单电极驻极体透过大鼠皮肤的表面电位更高、稳定性更好。驻极体作为一种新的物理调控因子和驱动源可用于透皮给药贴剂的研制。     

Potential of the adhesion of bacteria isolated from drinking water to materials

Heterotrophic bacteria (11 genera, 14 species, 25 putative strains) were isolated from drinking water, identified either biochemically or by partial 16s rDNA gene sequencing and their adherence characteristics were determined by two methods: i. thermodynamic prediction of adhesion potential by measuring hydrophobicity (contact angle measurements) and ii. by measuring adherence to eight different substrata (ASI 304 and 316 stainless steel, copper, polyvinyl chloride, polypropylene, polyethylene, silicone and glass). All the test organisms were hydrophilic and inter-species variation in hydrophobicity occurred only for Comamonas acidovorans. Stainless steel 304 (SS 304), copper, polypropylene (PP), polyethylene (PE) and silicone thermodynamically favoured adhesion for the majority of test strains (>18/25), whilst adhesion was generally less thermodynamically favorable for stainless steel 316 (SS 316), polyvinyl chloride (PVC) and glass. The predictability of thermodynamic adhesion test methods was validated by comparison with 24-well microtiter plate assays using nine reference strains and three adhesion surfaces (SS 316, PVC and PE). Results for Acinetobacter calcoaceticus, Burkolderia cepacia and Stenotrophomonas maltophilia sp. 2 were congruent between both methods whilst they differed for the other bacteria to at least one material. Only A. calcoaceticus had strongly adherent properties to the three tested surfaces. Strain variation in adhesion ability was detected only for Sphingomonas capsulata. Analysis of adhesion demonstrated that in addition to physicochemical surface properties of bacterium and substratum, biological factors are involved in early adhesion processes, suggesting that reliance on thermodynamic approaches alone may not accurately predict adhesion capacity.     

Non-electrolytic microelectroporation

Micro and nano technologies are of increasing importance in microfluidics devices used for electroporation (electroporation – the permeabilization of the cell membrane with brief high electric field pulses). Electrochemical reactions of electrolysis occur whenever an electric current flows between an electrode and an ionic solution. It can have substantial detrimental effects, both on the cells and solutions during the electroporation. As electrolysis is a surface phenomenon, between electrodes and solution, the extent of electrolysis is increased in micro and nano electroporation over macro-electroporation, because the surface area of the electrodes in micro and nano electroporation is much larger. A possible way to eliminate the electrolytic effect is to develop non-electrolytic microelectroporation by coating the microelectroporation devices with a dielectric insulating layer. In this study, we examine the effect of a dielectric insulating layer on the performance of a singularity microelectroporation device that we have recently designed. Using numerical analysis, we study the effects of various design parameters including, input sinusoidal voltage amplitude and frequency, geometrical configuration and material electrical properties on the electroporation performance of the non-electrolytic microelectroporation device. In the simulation, we used properties of four real dielectric materials and four solutions of interest for microelectroporation. We characterized the effect of various design parameters of relevance to singularity based microelectroporation, on non-electrolytic microelectroporation. Interestingly, we found that the system behaves in some aspects as a filter and in many circumstances saturation of performance is reached. After saturation is reached, changes in parameters will not affect the performance of the device.     

Electric current density distribution over the electrode surface of an autonomous electric stimulator of the gastrointestinal tract

Conclusion Thus, maximum density of electrical current is observed in the cylindrical part of the AES electrodes closer to the counter electrode. The inhomogeneity of the electrical current density distribution over the electrode surface is due to the specific shape and mutual orientation of the electrodes. Within the working range of electric stimulation currents, the inhomogeneity is substantially levelled because of nonlinearity of polarization characteristics of electrode material (12Kh18N9 stainless steel) in 1% solution of hydrochloric acid. The developed distributed model adequately describes the experimental data and it can be used for assessing functional performance and optimizing AES electrodes coated with various materials. Further development of the model could provide dynamic monitoring of the electrode-electrolyte system. Tomsk State Academy of Management Systems and Radioelectronics. Tomsk Polytechnical University. Translated from Meditsinskaya Tekhnika, No. 5, pp. 28–31, September–October, 1996.     

影响心肌细胞所受电场应力和膜内电能的因素

【摘要】目的:研究影响心肌细胞所受电场应力及细胞膜内储存电能改变的因素。方法:通过求解边值问题，得到细胞内外区域电势分布，并应用生物电磁学理论、电场应力张量法分析影响细胞膜内储存电能以及心肌细胞应力分布因素。结果:细胞半径越大，作用在细胞上的拉力与压力交界点对应极角越大，电场法向、切向应力随胞外介质介电常数变化率越大。在细胞半径较小范围内，电场引起的应力和膜内储存的电能随半径增加变化较大；否则，应力和电能随半径变化较小。结论:心肌细胞直径、胞外介质的介电常数均影响细胞所受的电场应力和细胞膜内储存的电能；半径较小的细胞，外加直流电场的影响更为明显；直流电场可引起细胞的形变、融合、旋转、离子跨膜迁移量的改变，产生细胞生物学效应。     

Surface mechanical properties, corrosion resistance, and cytocompatibility of nitrogen plasma-implanted nickel-titanium alloys: a comparative study with commonly used medical grade materials

Stainless steel and titanium alloys are the most common metallic orthopedic materials. Recently, nickel-titanium (NiTi) shape memory alloys have attracted much attention due to their shape memory effect and super-elasticity. However, this alloy consists of equal amounts of nickel and titanium, and nickel is a well known sensitizer to cause allergy or other deleterious effects in living tissues. Nickel ion leaching is correspondingly worse if the surface corrosion resistance deteriorates. We have therefore modified the NiTi surface by nitrogen plasma immersion ion implantation (PIII). The surface chemistry and corrosion resistance of the implanted samples were studied and compared with those of the untreated NiTi alloys, stainless steel, and Ti-6Al-4V alloy serving as controls. Immersion tests were carried out to investigate the extent of nickel leaching under simulated human body conditions and cytocompatibility tests were conducted using enhanced green fluorescent protein mice osteoblasts. The X-ray photoelectron spectroscopy results reveal that a thin titanium nitride (TiN) layer with higher hardness is formed on the surface after nitrogen PIII. The corrosion resistance of the implanted sample is also superior to that of the untreated NiTi and stainless steel and comparable to that of titanium alloy. The release of nickel ions is significantly reduced compared with the untreated NiTi. The sample with surface TiN exhibits the highest amount of cell proliferation whereas stainless steel fares the worst. Compared with coatings, the plasma-implanted structure does not delaminate as easily and nitrogen PIII is a viable way to improve the properties of NiTi orthopedic implants.     

The behavior of stainless steels in physiological solution containing complexing agent studied by X-ray photoelectron spectroscopy

The passive film formed by electrochemical oxidation on two different stainless steels differing in molybdenum (Mo) content in physiological solution with and without the addition of complexing agent, i.e., citrate, was studied using X-ray photoelectron spectroscopy. The alloys were polarized at different oxidation potentials in the electrochemical chamber attached to the spectrometer. Thus, the composition of the film formed by oxidation was analyzed by X-ray photoelectron spectroscopy without prior exposure to air (quasi in situ). The passive film formed in physiological solution consists of two predominant oxides, i.e., chromium and iron oxides. Oxides of alloying elements nickel and Mo are also detected in the film. It seems that the strong enrichment of oxidized chromium and Mo in the passive layer, and strong enrichment of Mo and depletion of iron at the metal surface underneath the passive layer, are responsible for the outstanding corrosion resistance of orthopedic stainless steel in physiological solution. Commercial AISI 304 is not suitable for orthopedic applications. The addition of complexing agent affects significantly the passivation behavior of orthopedic stainless steel, because it changes the distribution of the elements within the passive layer and at the metal surface underneath.