以蛋白质为基础的光电传感器的光电性质外文翻译.doc

机电工程学院毕业设计外文资料翻译设计题目: 基于光电技术的粮仓虫害检测系统设计 译文题目: 以蛋白质为基础的光电传感器的光电性质 学生姓名： 学 号： 专业班级： 指导教师： 正文：外文资料译文 附 件：外文资料原文 指导教师评语： 签名： 年 月 日正文:(外文资料译文)Optical Materials 21 (2003) 783788以蛋白质为基础的光电传感器的光电性质 摘要：细菌视紫红质(BR)已经被作为一种研究分子计算应用程序的生物材料，薄膜元素是基于BR在聚乙烯中具有确定的光电性能而发展起来的一种光电传感器。研究了属性注册光电压在时间，测量强度，区域和波长依赖性的光电响应,并评估元素质量。这个薄膜元素产生一个稳定的光电压，强度和面积依赖接近线性, 和吸收光谱BR的波长密切相关。元素薄膜的均匀性是基于相对较小的方差的光电响应，因此它是基于BR继续开发一种人工视网膜是可行的3。 关键词：光电器件；菌视紫红质；光电性质1. 引言特征尺寸在现代电路中的应用在过去的几十年里已经大大减小, 然而，量子力学的规律和制造技术的限制性在未来5-15年的时间里可能会阻止晶体三极管进一步小型化的产品特点的发展1。要继续发展电路元件到分子尺度，研究人员调查对超高密度电路的晶体管的替代品2，这些替代品基于新颖的电子，生物化学，机械或量子器件，通过集成电路来完成至少一部分的信息处理。由于现代电子技术有着坚实的发展的基础和悠久的历史，新的技术将最有可能首先出现在混合动力系统单芯片中。例如，可以结合生物分子薄膜固态电子形成的光电设备与模式识别能力3。细菌视紫红质（BR）光驱动质子泵发现在质膜中4它是一个光合成蛋白质，产生一个穿过细胞膜的光致质子梯度,这种电化学梯度可以通过化学渗透合成时发生ADP向ATP的转化产生能量4BR可以用作光敏感材料在光电器件中导致的质子泵特性的可能性，以测得光诱导电荷在材料中的位移。其中的优势是BR利用光质变色或电荷位移属性以设计出同时具有光学和电器设备的产品特性6这就是为什么注意力都被吸引到了对实施BR容量光存储器，光学图像单位和对颜色敏感的人造视网膜的应用程序的研究上7-9。 光电响应基于BR的电荷和位移属性的关系，光周期的中间状态在溶液中的研究已经有了相当大程度的研究，例如，10 - 13。在这项研究中，BR是固定在干燥的以生物材料为基础的能将光信号转换成电信号的传感器薄膜上，这项研究跟基于BR的智能人工视网膜的发展息息相关9，同时继续促进了BR在光学性能方面的研究14-19，改变了人们对光电子的特点的观点。2.光电传感器我们研究的薄膜元件准备通过野生型BR与聚乙烯醇（PVA）相结合以形成干膜，这些BR-PVA的尺寸大小约为2020毫米。紫膜（PM）片段是由BR分子和使用标准方法从脂类中分离出的古细菌的细胞组成的20， 离析后BR的浓度为13.6毫克/毫升，300uL BR 和750uL含有20的PVA的样品混合。BR悬浮液使用3uL的1 M磷酸盐缓冲液来中和，悬浮液被吸附在以SnO2为导电材料的玻璃制品上。我们使用重力涂布法使水蒸发和相对容易的产生薄膜处理，溅镀一层薄薄的金在膜上以实现反电极的功能。BR-PVA元件的输出阻抗为是几兆欧，因此当元件被连接到一个放大器上时实现阻抗匹配是必备的，运算放大器（TL082MJG）被用作尽可能与银涂料密切相关中。BR-PVA元件和电压跟随器被安装在一个铝制外壳内以减少周围环境的电磁干扰，照亮BR-PVA元件的窗户被49的透射率的金属网覆盖着。电压跟随器连接到无源RC滤波器（3dB截止频率7Hz）以去除直流响应。接下来，三个级联二阶滤波器 （3 dB截止频率5 kHz）被用于高频噪音消除，因为我们不需要实现最快的频率元件的光电响应。最后，使用一个放大系数为56的放大器(TL084AC)将反应放大，信号调理器被安装到另一个铝制外壳内。 3.测 量BR-PVA的光电性能包括光电响应测量时，被测量装置测量时响应的变化，并且面积，强度和响应的波长依赖性也被测量。执行测量并不是一个简单的任务，因为两个原因，首先，BR是一个中等大小的分子，不确切知道折叠蛋白的电荷转移过程。其次，一个薄的BR分子膜被嵌入到脂质双层和被PVA模型包围的PM片段中，这样的结果使得测量有一些不确定性的因素。 BR在溶液中和干燥膜中的光电响应已被广泛的研究，例如，10-13,21-23。当BR被合并到人工膜中时，被连续光照射时产生质子梯度膜（直流光电效应）。此外，如果光的短脉冲被用来激发BR分子可以产生快速的光电响应（交流光电效应）11。我们利用后者的现象变更记录照射中的变化。 BR-PVA的光电响应元件照亮的脉冲奥丽尔Q系列闪光灯图1所示， 在我们前面的测量结果（1.6 us至1ms),这种闪光灯相比照相机的闪光灯有相对更短的脉冲，。放电光源的能量是160mJ时，光脉冲的频率是1.0 赫兹。即使不饱和效应的光脉冲之间的时间间隔减小也没有什么明显的效果。反应后的峰 - 峰值电压扩增是4.57 V，信号噪声比48.9分贝。在光循环中由L至M过渡的时间常量约20毫秒，返回到基本的状态BR与BR-PVA薄膜相比过渡时间要慢三倍21。即使使用级联的低通滤波器，也可能观察到响应由几个与光循环的状态有关的部分组成。外界的光在测量过程中影响响应是因为它改变黑暗与光明的比例以改变BR分子造成一些分子加入到光电循环中。有几种可以实行的方法以除去周围环境光的影响：消除周围环境的光线，分子基本状态使用蓝光BR，或基于光循环状态BR和M的光谱吸收来估计明光和暗光的分子适应比例，和环境光的频谱辐射度，这些措施还没有投入到使用中。BR反应时这将很有可能涉及到一些相关参数的变化，但在尝试进一步的分析前通过光脉冲的长度和信号调理电路引起的效果应被考虑到。电压时 间接受 图1BR在PVA中的光电响应 BR的PM片段的取向是影响薄膜光电性能的因素，这是因为在质子泵BR吸收一个光子的分子是单向的，如果PM片段被随意的放置，一些碎片会减弱光响应的振幅13。有几种技巧使片段达到更好的方向放置24。在我们的例子中，我们没有任何方式控制干燥过程中PM片段的取向。然而，我们准备了一套由5种不同浓度的BR和8个不同的稀释液组成的40个样本装置， BR在稀释液的浓度分别为1.31，2.62，3.76，5.27和6.58毫克/毫升。这些装置测量怎么看不同浓度的BR对膜中光电反应的影响，光电反应的不同给出了影响特性变化的因素。测量结果如图2所示，从图中可以看出的光电反应强度与BR浓度的关系，可以看出任何浓度的BR对反应的影响都相对较小（均方差54 MV2）。没有不能实现的参数因素，但有两种缺陷，这些因素在计算时没有被考虑到，被认为是制造时，单个周期的BR薄膜良好的稳定性是基于相对小的光电反应的变化。良好的稳定性可以理解为循环光电子数目或分子的时间保持功能。 BR可以通过光循环被回收超过106次7和我们的BR-PVA分子的功能三年内还没有被改变。光电响应的电压平均振幅 BR 浓 度图2 40组BR在PVA中光电响应的平均振幅，8组稀释液的竖线说明了响应的变化和不同浓度的BR的响应差异，有盒子的金属层具有响应缺陷。要确定改变BR-PVA的照明度对光电子反应的线性度的影响，我们使用从30至150毫焦耳的脉冲闪光灯，在照明度的范围内扩大，使用中性为6 的密度滤光片（NDF）以涉及到较低的标准。峰-峰值的照片电压对辐射能光源的影响如图3所示。在这项测量中我们使用一个恒定频率的光脉冲（1.0赫兹）。利用光源测得的红外辐射率光谱的能量来估计的辐射能量，测得NDF的吸光度和照明壳体的窗口的透明度，和一个纠正辐射能量释放的非线性的二阶多项式。结果表明，辐射能源的依赖元素是非常接近线性辐射能量范围内的检查，从约20nJ到20uJ,反应的变化是合理的（均值方差约为0.39MV2）。这些事实表明，该元件可以用于区分不同的照明标准。 辐 射 能响应幅度 图3 在BR-PVA中使用NDF时光电响应对辐射能的影响，每个响应平均提出20个读数 我们还通过改变照明面积确定了BR-PVA元件的光电响应对面积的依赖性，这是研究可扩展性所必备的。首先，金层顶部的BR-PVA膜的低导电率的造成不合逻辑的结果。我们测验具有不同的厚度的金层试验结果表明合适的反电极厚度为150nm。测得的最终结果的面积依赖性如图4所示显示了响应和照明面积的线性关系，然而并没有给出下限尺度。 照 明 面 积响应 图4 BR-PVA中光电响应跟面积的关系BR-PVA对光电反应的波长依赖性影响通过使用16 NAR干扰过滤器覆盖了整个可见光谱滤除光线测得。使用一个恒定的频率（1.0赫兹）和恒定的放电能量（150MJ）的光脉冲记录峰-峰值电压，光源的非理想性的辐射光谱使用补偿照射光谱制造商的数据源和测量干涉滤光器的透射率。标准的补偿结果如图5所示，每种元素的光谱跟吸收光谱的元素密切相关。应该注意到光谱的数字化吸收并不是具有特定的光电响应的基础的视网膜对光的吸收率25，从而由于材料造成的一些吸光度的变化是可以预料到的。 波 长归一化补偿响应图5 光电响应中的波长与BR-PVA中光谱吸收的关系4.结 论 本研究的目的是确定BR-PVA的光电性能以促进光电传感器和成像装置的发展，结果表明：经过滤除噪音后的元器件的光电响应具有稳定性，BR浓度越高，光电响应越剧烈，并且响应过程具有可靠性。在测量范围内很容易测得采用不同的亮度时辐射能量与响应线性相关，响应与面积大小的线性关系使得尽可能的减小成像设备的尺寸具有可行性，响应的波长与BR的光谱吸收密切相关。研究结果表明了制造一种光电传感器的材料和方法。 致 谢该研究项目已经得到了芬兰国家技术局和芬兰科学院的支持，我们非常感谢迪特尔奥斯蒂希特教授在BR知识方面的帮助，佩尔蒂博士在物理测量上的帮助，以及马尔科硕士在项目中所做的努力。参考文献1国际半导体技术路线图，半导体行业协会，2000年。2 D.戈德哈贝尔 - 戈登，M. 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Parkkinen 光学材料12（1999）473。18 Y.O.Barmenkov，亚诺夫，A. Starodumov，V.-P.万哈宁，耶斯凯莱伊宁，N. Kozhevnikov，激光物理10（2000）60。19 J.万哈宁，S. Parkkinen，V.-P. Leppanen，T. Jaaskelainen，J. Parkkinen，光学评论（2001）368。20 D.奥斯蒂希特，W. Stoeckenius，酶学方法（1974）667。21 K. Bryl， G. Varo，R. Drabent，费用说明285（1）（1991）66。22 L. Lensu，J. Parkkinen，S. Parkkinen，M. Palviainen，T.耶斯凯莱伊宁：智能系统与应用，ISA 2000，澳大利亚，2000年。23 L. Lensu，M. Frydrych，C. Ascbi，J. Parkkinen，S.Parkkinen，T.耶斯凯莱伊宁，2001年国际会议计算技术会议的记录 纳米科学，ICCN 2001年，希尔顿黑德岛，南卡罗来纳州，美国，2001年，p. 5。24 H.-W.Trissl，光化学和光生物学，51（6）（1990）793。25 M. Frydrych，L. Lensu，J. Parkkinen，2001年国际会议上提出的纳米科学，ICCN 2001年，南卡罗来纳州，美国，2001年。附件：(外文资料原文) Photoelectrical properties of protein-based optoelectronic sensor Abstract：Bacteriorhodopsin (BR) has been studied as a biomaterial for molecular computing applications. Thin film elements based on BR in polyvinylalcohol were prepared to determine the photoelectrical properties of the material for the development of an optoelectronic sensor. The properties were studied by registering the photovoltage in time, measuring the intensity, area and wavelength dependence of the photoelectric response, and evaluating the element quality.The thin film elements produce a stable photovoltage, the intensity and area dependencies are close to linear, and the wavelength dependence is closely related to the absorption spectrum of BR. The homogeneity of the element thin films is good based on the relatively small variance of the photoelectric response, thus it is feasible to continue the development of an artificial retina based on BR.2002 Elsevier Science B.V. All rights reserved.Keywords: Optoelectronic devices; Bacteriorhodopsin; Photoelectrical properties1. IntroductionThe feature size in modern electrical circuits has shrunk considerably during the past decades. However, the laws of quantum mechanics and limitations of fabrication technology may prevent further miniaturization of the features in today，s field-effect transistors within the next 515 years1. To continue the downscaling of circuit elements down to the molecular scale, researchers are investigating several alternatives to the transistor for ultra-dense circuitry 2. These alternatives are based on novel electronic, biochemical, mechanical or quantum devices to perform at least portion of the information processing handled by integrated circuits. Since modern electronics has a solid foundation and a long history of development, it is most likely that new technologies will first appear as parts of hybrid systems-on-a-chip. For example, biomolecular thin films can be combined with solid-state electronics to form an optoelectronic device with pattern recognition capabilities 3. Bacteriorhodopsin (BR) is the light-driven proton pump found in the plasma membrane of Halobacterium salinarum 4. It is a photo-synthetic protein that generates a light-induced proton gradient across the cell membrane. This electrochemical gradient is used by the archaean to produce energy by the chemiosmotic synthesis of ATP from ADP 5. BR can be used as the light-sensitive material in an optoelectronic device because of the proton-pumping characteristic and the possibility to sense the light-induced charge displacements in the material. One of the advantages of BR is the potential to design both optical and electrical devices using the photochromism or the charge-displacement property 6. This is why attention has been drawn to the applications of BR to implement volumetric optical memories,holographic storage devices, optical image processing units and color-sensitive artificial retinas79. The photoelectric response based on the charge displacement property of BR and its relation tothe intermediate states of the photocycle has been considerably studied in solution, for example 1013. In this study BR is immobilized in dried thin films which are studied as biomaterial-based sensors capable of converting light into an electric signal. This study is related to the development of an intelligent artificial retina based on BR 9, and continues the research on optical properties of BR1419 changing the point of view to photoelectrical properties.2. Optoelectronic sensorThe thin film elements of our study were prepared by combining wild-type BR with polyvinyl-alcohol (PVA) to form a dry film. The size of these BRPVA elements was about 20 20 mm. The purple membrane (PM) fragments consisting of BR molecules and lipids were isolated from the archaeal cells using a slightly modified version of the standard method 20. The concentration of BR after isolation was 13.6 mg/ml. 300 ll of BR sample was mixed with 750 ll of 20% PVA. The BR suspension was neutralized using 3 ll of 1 M phosphate buffer. The suspension was pipeted on conductive glass with SnO2as the conductive layer. We used the gravity coating method to evaporate water and produce thin films which are easy to handle. A thin layer of gold was sputtered on top of the film to function as the counter electrode. The output impedance of the BRPVA element is several megaohms, thus impedance matching is needed when the element is connected to an amplifier. An operational amplifier (TL082MJG) was used as a voltage follower which was connected to the element as closely as possible with silver paint. The BRPVA element and the voltage follower were installed into an aluminum housing to reduce electromagnetic interference from the environment. The window to illuminate the BRPVA element was covered by a metallic mesh with a transmittance of 49%. The voltage follower was connected to a passive RC filter (-3 dB cutoff frequency 7 Hz) to remove the DC from the response. Next, three cascaded second-order filters(-3 dB cutoff frequency 5 kHz) were used for high frequency noise cancellation since the fastest components of the photoelectric response are not needed in our implementation. Last, the response was amplified using an operational amplifier (TL084AC) for which the amplification coefficient was 56. The signal conditioning circuits were installed into another aluminum housing.3. Measurements The photoelectrical properties of the BRPVA elements including the photoelectric response in time, the variance of the response when measured from a set of elements, and the area, intensityand wavelength dependence of the response were measured. Performing the measurements is not astraightforward task because of two reasons. First, BR is a moderately large molecule, a folded protein for which the charge transfer process is not exactly known. Second, the BR molecules in a thin film are embedded into the lipid bilayer and the PM fragments are surrounded by the PVA matrix,thus the results are subject to some modelling uncertainty. The photoelectric responses of BR in solution and in dried films has been widely studied, forexample 1013,2123. When BR is incorporated into an artificial membrane, illumination by continuous light generates a proton gradient across the membrane (DC photoelectric effect). Additionally, a fast photoelectric response can be registered if a short pulse of light is used to excite the BR molecules (AC photoelectric effect) 11. We use the latter phenomenon to register the changes in the illumination. The photoelectric response from the BRPVA element illuminated by the pulsed Oriel series Q flashlamp is shown in Fig. 1. The flashlamp has a considerably shorter pulse than the camera flash used in our earlier measurements (1.6 us vs. 1ms). The discharge energy of the light source was 160mJ, and the frequency of light pulses was 1.0 Hz. No saturation effects were noticed even when the interval between the light pulses was decreased. The peak-to-peak voltage of the response after amplification was 4.57 V, and the signal-to-noise ratio 48.9 dB. The time constant of the L ! M transition in the photocycle, about 20 ms, is three orders of magnitude slower than and the return back to the basic state BR is comparable to the results obtained by others studying BRPVA thin films 21. Even with the cascaded low-pass filters,it was possible to observe that the response consists of several components related to the intermediate states of the photocycle. Ambient light during the measurement affects the response because it changes the proportion of dark and light adapted BR molecules in the element and causes some molecules to initiate the photocycle. There are several possibilities to remove the effect of ambient light: remove the ambient light, force the molecules to the basic state BR using blue light, or estimate the proportion of dark and light adapted molecules based on the absorption spectra of photocycle states BR and M, and the irradiance spectrum of ambient light. The measures have not been taken into use. It would be possible to determine some of the parameters involved in the operation of BR from the response but the effects caused by the length of the light pulse and the signal conditioning circuitry should be considered before attempting further analysis. The orientation of the PM fragments in a BR thin film affect the photoelectrical performance of the element. This is because proton pumping in a BR molecule due to the absorption of a photon is unidirectional. If the PM fragments were randomly oriented, some fragments would attenuate the amplitude of the photoresponse 13. There are several techniques to achieve better orientation of the fragments 24. In our case, we did not control the orientation in any way during the drying process. However, we prepared a set of 40 elements consisting of 5 dilutions of BR and 8 elements per dilution. The concentrations of BR in the dilutions were 1.31, 2.62, 3.76, 5.27 and 6.58 mg/ml. The set was measured to see how the concentration of BR in the film affects the photoelectric response and the variance of the response which give an indication of the quality of the elements. The result of the measurements is shown in Fig. 2. It can be seen that the strength of the photoelectric response increases with the concentration of BR. The variance of the response for any concentration of BR can be seen relatively small (mean variance 54 mV2). None of the elements was inoperable but two of the elements contained defects in the gold layer. These elements were not taken into account in the calculations. When manufacturing is considered, single cycle stability of the BR films is good based on the relatively small variance of the response. The aging stability can be understood as the number of photocycles or the time which the molecule stays functional. BR can be recycled through the photocycle over 106times 7 and the functionality of our BRPVA elements has not changed within three years. To determine the linearity of the photoelectric response from the BRPVA element under changing illumination, we varied the discharge energy of the pulsed flashlamp from 30 to 150mJin 30mJ steps. The range of illumination level was widened to cover lower levels using six neutral density filters (NDF). The peak-to-peak photo voltage against the estimated radiant energy of thelight source is shown in Fig. 3. In this measurement we used a constant frequency of light pulses(1.0 Hz). The radiant energy has been estimated from the discharge energy using the measured irradiance spectrum of the light source, the measured absorbances of the NDF, the measured transmittance of the window for illumination in the housing, and a second-order polynomial to correct the non-linearity of radiant energy against discharge energy. The result shows that the radiant energy dependence of the element is very close to linear within the inspected range of radiant energy, from about 20nJ to 20uJ, and the variance of the response is reasonable (mean variance about 0.39 mV2). These facts indicate that the element can be used to discriminate different levels of illumination. We also determined the area dependence of the photoelectric response from the BRPVA element by varying the illuminated area. This was performed to study scalability of the element. At first, low conductivity of the golden layer on top of the BRPVA film caused illogical results. Our tests with elemen