1、 機電工程學院畢業(yè)設計外文資料翻譯設計題目:基于光電技術的糧倉蟲害檢測系統(tǒng)設計 譯文題目: 以蛋白質為基礎的光電傳感器的光電性質 學生姓名：學號：專業(yè)班級：指導教師：正文：外文資料譯文 附 件：外文資料原文 指導教師評語： 簽名： 年 月 日正文:(外文資料譯文)Optical Materials 21 (2003) 783788以蛋白質為基礎的光電傳感器的光電性質摘要：細菌視紫紅質(BR)已經被作為一種研究分子計算應用程序的生物材料，薄膜元素是基于BR在聚乙烯中具有確定的光電性能而發(fā)展起來的一種光電傳感器。研究了屬性注冊光電壓在時間，測量強度，區(qū)域和波長依賴性的光電響應,并評估元素質量。這個

2、薄膜元素產生一個穩(wěn)定的光電壓，強度和面積依賴接近線性, 和吸收光譜BR的波長密切相關。元素薄膜的均勻性是基于相對較小的方差的光電響應，因此它是基于BR繼續(xù)開發(fā)一種人工視網膜是可行的3。關鍵詞：光電器件；菌視紫紅質；光電性質1. 引言特征尺寸在現代電路中的應用在過去的幾十年里已經大大減小, 然而，量子力學的規(guī)律和制造技術的限制性在未來5-15年的時間里可能會阻止晶體三極管進一步小型化的產品特點的發(fā)展1。要繼續(xù)發(fā)展電路元件到分子尺度，研究人員調查對超高密度電路的晶體管的替代品2，這些替代品基于新穎的電子，生物化學，機械或量子器件，通過集成電路來完成至少一部分的信息處理。由于現代電子技術有著堅實的發(fā)

3、展的基礎和悠久的歷史，新的技術將最有可能首先出現在混合動力系統(tǒng)單芯片中。例如，可以結合生物分子薄膜固態(tài)電子形成的光電設備與模式識別能力3。細菌視紫紅質（BR）光驅動質子泵發(fā)現在質膜中4它是一個光合成蛋白質，產生一個穿過細胞膜的光致質子梯度,這種電化學梯度可以通過化學滲透合成時發(fā)生ADP向ATP的轉化產生能量4BR可以用作光敏感材料在光電器件中導致的質子泵特性的可能性，以測得光誘導電荷在材料中的位移。其中的優(yōu)勢是BR利用光質變色或電荷位移屬性以設計出同時具有光學和電器設備的產品特性6這就是為什么注意力都被吸引到了對實施BR容量光存儲器，光學圖像單位和對顏色敏感的人造視網膜的應用程序的研究上7-9

4、。 光電響應基于BR的電荷和位移屬性的關系，光周期的中間狀態(tài)在溶液中的研究已經有了相當大程度的研究，例如，10 - 13。在這項研究中，BR是固定在干燥的以生物材料為基礎的能將光信號轉換成電信號的傳感器薄膜上，這項研究跟基于BR的智能人工視網膜的發(fā)展息息相關9，同時繼續(xù)促進了BR在光學性能方面的研究14-19，改變了人們對光電子的特點的觀點。2.光電傳感器我們研究的薄膜元件準備通過野生型BR與聚乙烯醇（PVA）相結合以形成干膜，這些BR-PVA的尺寸大小約為20×20毫米。紫膜（PM）片段是由BR分子和使用標準方法從脂類中分離出的古細菌的細胞組成的20， 離析后BR的濃度為13.6毫

5、克/毫升，300uL BR 和750uL含有20的PVA的樣品混合。BR懸浮液使用3uL的1 M磷酸鹽緩沖液來中和，懸浮液被吸附在以SnO2為導電材料的玻璃制品上。我們使用重力涂布法使水蒸發(fā)和相對容易的產生薄膜處理，濺鍍一層薄薄的金在膜上以實現反電極的功能。BR-PVA元件的輸出阻抗為是幾兆歐，因此當元件被連接到一個放大器上時實現阻抗匹配是必備的，運算放大器（TL082MJG）被用作盡可能與銀涂料密切相關中。BR-PVA元件和電壓跟隨器被安裝在一個鋁制外殼內以減少周圍環(huán)境的電磁干擾，照亮BR-PVA元件的窗戶被49的透射率的金屬網覆蓋著。電壓跟隨器連接到無源RC濾波器（3dB截止頻率7Hz）以

6、去除直流響應。接下來，三個級聯二階濾波器 （3 dB截止頻率5 kHz）被用于高頻噪音消除，因為我們不需要實現最快的頻率元件的光電響應。最后，使用一個放大系數為56的放大器(TL084AC)將反應放大，信號調理器被安裝到另一個鋁制外殼內。3.測量BR-PVA的光電性能包括光電響應測量時，被測量裝置測量時響應的變化，并且面積，強度和響應的波長依賴性也被測量。執(zhí)行測量并不是一個簡單的任務，因為兩個原因，首先，BR是一個中等大小的分子，不確切知道折疊蛋白的電荷轉移過程。其次，一個薄的BR分子膜被嵌入到脂質雙層和被PVA模型包圍的PM片段中，這樣的結果使得測量有一些不確定性的因素。 BR在溶液中和干燥

7、膜中的光電響應已被廣泛的研究，例如，10-13,21-23。當BR被合并到人工膜中時，被連續(xù)光照射時產生質子梯度膜（直流光電效應）。此外，如果光的短脈沖被用來激發(fā)BR分子可以產生快速的光電響應（交流光電效應）11。我們利用后者的現象變更記錄照射中的變化。 BR-PVA的光電響應元件照亮的脈沖奧麗爾Q系列閃光燈圖1所示， 在我們前面的測量結果（1.6 us至1ms),這種閃光燈相比照相機的閃光燈有相對更短的脈沖，。放電光源的能量是160mJ時，光脈沖的頻率是1.0 赫茲。即使不飽和效應的光脈沖之間的時間間隔減小也沒有什么明顯的效果。反應后的峰 - 峰值電壓擴增是4.57 V，信號噪聲比48.9分

8、貝。在光循環(huán)中由L至M過渡的時間常量約20毫秒，返回到基本的狀態(tài)BR與BR-PVA薄膜相比過渡時間要慢三倍21。即使使用級聯的低通濾波器，也可能觀察到響應由幾個與光循環(huán)的狀態(tài)有關的部分組成。外界的光在測量過程中影響響應是因為它改變黑暗與光明的比例以改變BR分子造成一些分子加入到光電循環(huán)中。有幾種可以實行的方法以除去周圍環(huán)境光的影響：消除周圍環(huán)境的光線，分子基本狀態(tài)使用藍光BR，或基于光循環(huán)狀態(tài)BR和M的光譜吸收來估計明光和暗光的分子適應比例，和環(huán)境光的頻譜輻射度，這些措施還沒有投入到使用中。BR反應時這將很有可能涉及到一些相關參數的變化，但在嘗試進一步的分析前通過光脈沖的長度和信號調理電路引起

9、的效果應被考慮到。電壓時 間接受 圖1BR在PVA中的光電響應 BR的PM片段的取向是影響薄膜光電性能的因素，這是因為在質子泵BR吸收一個光子的分子是單向的，如果PM片段被隨意的放置，一些碎片會減弱光響應的振幅13。有幾種技巧使片段達到更好的方向放置24。在我們的例子中，我們沒有任何方式控制干燥過程中PM片段的取向。然而，我們準備了一套由5種不同濃度的BR和8個不同的稀釋液組成的40個樣本裝置， BR在稀釋液的濃度分別為1.31，2.62，3.76，5.27和6.58毫克/毫升。這些裝置測量怎么看不同濃度的BR對膜中光電反應的影響，光電反應的不同給出了影響特性變化的因素。測量結果如圖2所示，從

10、圖中可以看出的光電反應強度與BR濃度的關系，可以看出任何濃度的BR對反應的影響都相對較?。ň讲?4 MV2）。沒有不能實現的參數因素，但有兩種缺陷，這些因素在計算時沒有被考慮到，被認為是制造時，單個周期的BR薄膜良好的穩(wěn)定性是基于相對小的光電反應的變化。良好的穩(wěn)定性可以理解為循環(huán)光電子數目或分子的時間保持功能。 BR可以通過光循環(huán)被回收超過106次7和我們的BR-PVA分子的功能三年內還沒有被改變。光電響應的電壓平均振幅 BR 濃 度圖2 40組BR在PVA中光電響應的平均振幅，8組稀釋液的豎線說明了響應的變化和不同濃度的BR的響應差異，有盒子的金屬層具有響應缺陷。要確定改變BR-PVA的照

11、明度對光電子反應的線性度的影響，我們使用從30至150毫焦耳的脈沖閃光燈，在照明度的范圍內擴大，使用中性為6 的密度濾光片（NDF）以涉及到較低的標準。峰-峰值的照片電壓對輻射能光源的影響如圖3所示。在這項測量中我們使用一個恒定頻率的光脈沖（1.0赫茲）。利用光源測得的紅外輻射率光譜的能量來估計的輻射能量，測得NDF的吸光度和照明殼體的窗口的透明度，和一個糾正輻射能量釋放的非線性的二階多項式。結果表明，輻射能源的依賴元素是非常接近線性輻射能量范圍內的檢查，從約20nJ到20uJ,反應的變化是合理的（均值方差約為0.39MV2）。這些事實表明，該元件可以用于區(qū)分不同的照明標準。 輻 射 能響應幅

12、度 圖3 在BR-PVA中使用NDF時光電響應對輻射能的影響，每個響應平均提出20個讀數 我們還通過改變照明面積確定了BR-PVA元件的光電響應對面積的依賴性，這是研究可擴展性所必備的。首先，金層頂部的BR-PVA膜的低導電率的造成不合邏輯的結果。我們測驗具有不同的厚度的金層試驗結果表明合適的反電極厚度為150nm。測得的最終結果的面積依賴性如圖4所示顯示了響應和照明面積的線性關系，然而并沒有給出下限尺度。 照 明 面 積響應圖4BR-PVA中光電響應跟面積的關系BR-PVA對光電反應的波長依賴性影響通過使用16 NAR干擾過濾器覆蓋了整個可見光譜濾除光線測得。使用一個恒定的頻率（1.0赫茲）

13、和恒定的放電能量（150MJ）的光脈沖記錄峰-峰值電壓，光源的非理想性的輻射光譜使用補償照射光譜制造商的數據源和測量干涉濾光器的透射率。標準的補償結果如圖5所示，每種元素的光譜跟吸收光譜的元素密切相關。應該注意到光譜的數字化吸收并不是具有特定的光電響應的基礎的視網膜對光的吸收率25，從而由于材料造成的一些吸光度的變化是可以預料到的。 波 長歸一化補償響應圖5 光電響應中的波長與BR-PVA中光譜吸收的關系4.結論 本研究的目的是確定BR-PVA的光電性能以促進光電傳感器和成像裝置的發(fā)展，結果表明：經過濾除噪音后的元器件的光電響應具有穩(wěn)定性，BR濃度越高，光電響應越劇烈，并且響應過程具有可靠性。

14、在測量范圍內很容易測得采用不同的亮度時輻射能量與響應線性相關，響應與面積大小的線性關系使得盡可能的減小成像設備的尺寸具有可行性，響應的波長與BR的光譜吸收密切相關。研究結果表明了制造一種光電傳感器的材料和方法。致 謝該研究項目已經得到了芬蘭國家技術局和芬蘭科學院的支持，我們非常感謝迪特爾·奧斯蒂希特教授在BR知識方面的幫助，佩爾蒂博士在物理測量上的幫助，以及馬爾科碩士在項目中所做的努力。參考文獻1國際半導體技術路線圖，半導體行業(yè)協(xié)會，2000年。2 D.戈德哈貝爾 - 戈登，M. Montemerlo，J.樂福，G.opiteck，J. Ellenbogen，IEEE85論文集（4）

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17、.山口，T.宮坂，科學265（八月）（1994年）762。14 T.耶斯凱萊伊寧，V.-P. Leppanen Parkki, S. Parkkinen，光學材料（1996）339。15 Y. Barmenkov，V.-P. Leppanen，T.耶斯凱萊伊寧，N.Kozhevnikov，在非線性光學材料基礎與應用專題 荷蘭國際集團，1998年，p.355。16 V.-P.耶斯凱萊伊寧，T.哈林，E.瓦爾蒂艾寧，S. Parkkinen，J. Parkkinen，光學通訊163（1999年）189。17 J.萬哈寧，V.-P. Leppanen，T.耶斯凱萊伊寧，S. Parkkinen， J

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20、1年，南卡羅來納州，美國，2001年。附件：(外文資料原文)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 pr

21、operties 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 st

22、able 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 t

23、o 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.

24、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 investigat

25、ing 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 foundati

26、on 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. Bacteriorh

27、odopsin (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

28、 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 optic

29、al 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 p

30、hotoelectric 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 o

31、f 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 o

32、f 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 o

33、f 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 g

34、ravity 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 c

35、onnected 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

36、 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 freq

37、uency 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 condition

38、ing 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 resp

39、onse 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

40、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 continuou

41、s 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 illu

42、mination. 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 160m

43、J, 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

44、 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 c

45、omponents 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 r

46、emove 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 mea

47、sures 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 or

48、ientation 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

49、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 concentra

50、tions 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

51、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

52、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 th

53、e 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

54、 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 m

55、easurement 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,

56、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

57、 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 sca

58、lability of the element. At first, low conductivity of the golden layer on top of the BRPVA film caused illogical results. Our tests with elements having different thicknesses of gold layers showed that a suitable thickness for the counter electrode is 150nm. The final result of area dependence is shown in Fig. 4 showing the close to linear dependence between the response and the illuminated area. This does not