201024727 九、發明說明： 【發明所屬之技術領域】 本發明係關於一種生醫感測器，詳言之，係關於一種應 用於甲胎兒蛋白檢測之彎曲平板波生醫感測器。 【先前技術】 因為人類對於健康問題的重視與需求日益增加所以導致 生物科技與生醫檢測產業的快速發展，其中又以可以結合 半導趙1C產業科技的生物晶片（Bi〇Chips)或生醫微機電系 統（BioMEMS)最引人著目。人體的免疫系統具有保護身體 免於受病毒、細菌、癌細胞及微生物侵害的功能，但如果 免疫系統過度反應，則會造成過敏症、休克，甚至致死。 其中日益嚴重的肝癌之檢測，主要判定標的是病患血清 中甲胎兒蛋白之濃度值。在生物醫學領域的應用上，目前 被廣泛應用於測量人體血清中甲型胎兒蛋白濃度的商用檢 測分析儀主要有：RIA、ELISA & CLIA。 1·放射免疫分析實驗（RIA)是由美國柏森醫師與生物物 理學家蘿沙琳耶洛博士於1959年共同研製開發的技術，其 方法與原理乃藉生物體免疫中抗原、抗體反應為基礎加上 數學公式導引分析的方式，偵測人體組織液，體液、血 清、血漿、尿等生物體微量濃度，以診斷或追蹤許多内分 泌代謝疾病、腫瘤、藥物中毒或藥物不足，其缺點為：（i) 只能偵測有活性之物質；（ii)穩定性易受環境因素彩響； 及（iii)存在放射性污染的問題。 2. ELISA是繼RIA法之後發展起來的免疫酵素技術，此 136428.doc 201024727 項技術自從70年代問世以來，因具有準確度高、高靈敏度 (1.0 IU/ml)與操作簡單等優點；但其缺點為儀器昂貪（約新 台幣300000元）、線性範圍窄（5〜3〇〇 ng/mi，即4.1 7〜250 IU/ml)、穩定度低與操作費時（12〇·15〇 min)。目前國内外 有許多醫療研究單位使用此系統作為臨床檢驗或研究上的 分析。ELISA是以免疫學為基礎，將抗原、抗體的專一性 反應結合加上酵素的呈色反應或螢光物質的發光，以檢測 特定種類的蛋白質濃度。 3. CLIA的原理是將化學發光或生物發光體系與免疫反 應相互結合，用於檢測微量抗原或抗體的一種新型免疫標 記技術’具有高靈敏度（1.0 IU/ml)以及檢測儀器簡單之優 點，但其儀器昂貴（約新台幣700000元）、線性範圍窄 (1.0〜100 rig/nU，即〇.83〜83.3 IU/ml)、重複性不高、操作 費時（120-150 min)以及外在干擾因素不易評估。 另外，學術論文所發表相關的習知微型甲型胎兒蛋白檢 φ 測器有··電化學生物感測，利用兩電極間導電電流的大小 來觀察血清中甲型胎兒蛋白的濃度，其優點是高靈敫度與 高線性範圍，但其試劑用量相對較多（9〇 μ1)且需要參考電 極的輔助（參考先前技術文獻[1]);及，電容式流體生入生 物感測器，利用抗體鍵結導致電容變化來得到血清中甲胎 兒蛋白濃度之關係，優點是有極高的感測靈敏度（約10 ngr1);其缺點為線性範圍窄，且試劑耗董大（25〇 μΐ)(參考 先前技術文獻[2])。 先前技術文獻： 136428.doc -7· 201024727 1. Eun Ju Kim, Yasuko Yanagida, Tetsuya Haruyama, Eiry Kobatake and Masuo Aizawa, "Immunosensing system for a-fetoprotein coupled with a disposable amperometric glucose oxidase sensor," Sensors and Actuators B: Chemical, Volume 79, Issues 2-3, 2001, pp. 87-91. 2. Warakorn Limbut, Proespichaya Kanatharana, Bo Mattiasson,201024727 IX. DESCRIPTION OF THE INVENTION: TECHNICAL FIELD OF THE INVENTION The present invention relates to a biomedical sensor, and more particularly to a curved flat wave biomedical sensor for use in the detection of alpha fetal protein. [Prior Art] Because of the increasing emphasis on human health and the increasing demand for biomedical and biomedical testing industries, biofilms (Bi〇Chips) or biomedicine that can be combined with semi-conductor 1C industrial technology are also available. MicroMEMS (BioMEMS) is the most eye-catching. The body's immune system protects the body from viruses, bacteria, cancer cells and microbes, but if the immune system overreacts, it can cause allergies, shock, and even death. Among the increasingly serious tests for liver cancer, the main criterion is the concentration of alpha-fetoprotein in the serum of patients. In biomedical applications, commercial assays that are currently widely used to measure the concentration of alpha-fetoprotein in human serum include: RIA, ELISA & CLIA. 1. Radioimmunoassay Experiment (RIA) is a technology jointly developed by Dr. Burson and biophysicist Dr. Rosarin Yello in 1959. The method and principle are based on the antigen and antibody reactions in biological immunity. In addition to the mathematical formula to guide the analysis, detect human body fluids, body fluids, serum, plasma, urine and other biological micro-concentration to diagnose or track many endocrine and metabolic diseases, tumors, drug poisoning or drug deficiency, the shortcomings are: i) can only detect active substances; (ii) stability is susceptible to environmental factors; and (iii) radioactive contamination. 2. ELISA is an immunoenzyme technology developed after the RIA method. This 136428.doc 201024727 technology has been used since the 1970s because of its high accuracy, high sensitivity (1.0 IU/ml) and simple operation; The shortcoming is that the instrument is greedy (about NT$300,000), the linear range is narrow (5~3〇〇ng/mi, ie 4.1 7~250 IU/ml), the stability is low and the operation time is low (12〇·15〇min) . At present, many medical research units at home and abroad use this system as a clinical test or research analysis. ELISA is based on immunology to combine the specific reaction of antigens and antibodies with the color reaction of enzymes or the luminescence of fluorescent substances to detect specific protein concentrations. 3. The principle of CLIA is to combine a chemiluminescent or bioluminescent system with an immune response, and a novel immunolabeling technique for detecting trace antigens or antibodies has the advantages of high sensitivity (1.0 IU/ml) and simple instrumentation, but The instrument is expensive (about NT$700,000), narrow linear range (1.0~100 rig/nU, ie 〇.83~83.3 IU/ml), low repeatability, time-consuming operation (120-150 min) and external interference Factors are not easy to assess. In addition, the related micro-type fetal protein detection φ detector published in the academic paper has electrochemical biosensing, and the concentration of the type A fetal protein in the serum is observed by the magnitude of the conduction current between the two electrodes. High-intensity and high linear range, but the reagent dosage is relatively high (9〇μ1) and requires the assistance of reference electrode (refer to the prior art literature [1]); and, capacitive fluid is generated into the biosensor, using Antibody binding leads to a change in capacitance to obtain a relationship between the concentration of alpha-fetoprotein in serum. The advantage is that it has a very high sensitivity (about 10 ngr1); its disadvantage is that the linear range is narrow and the reagent consumption is large (25 μμΐ). Refer to the prior art document [2]). Prior Technical Literature: 136428.doc -7· 201024727 1. Eun Ju Kim, Yasuko Yanagida, Tetsuya Haruyama, Eiry Kobatake and Masuo Aizawa, "Immunosensing system for a-fetoprotein coupled with a disposable amperometric glucose oxidase sensor," Sensors and Actuators B: Chemical, Volume 79, Issues 2-3, 2001, pp. 87-91. 2. Warakorn Limbut, Proespichaya Kanatharana, Bo Mattiasson,
Punnee Asawatreratanakul and Panote Thavarungkul, "A comparative study of capacitive immunosensors based on self-assembled monolayers formed from thiourea, thioctic acid, and 3-mercaptopropionic acid," Biosensors andPunnee Asawatreratanakul and Panote Thavarungkul, "A comparative study of capacitive immunosensors based on self-assembled monolayers formed from thiourea, thioctic acid, and 3-mercaptopropionic acid," Biosensors and
Bioelectronics, Volume 22, Issue 2, 2006, pp. 233-240. 【發明内容】 本發明提供一種應用於甲胎兒蛋白檢測之彎曲平板波生 醫感測器，其包括：一彎曲平板波元件及一自我組裝單分 子結構。該彎曲平板波元件具有一内凹的空腔及一導電 層，該導電層形成於該空腔之表面》該自我組裝單分子結 構設置於該空腔，其包括：一自我組裝單分子層、一橋接 層及一甲胎兒蛋白抗體層。該自我組裝單分子層具有複數 個自我組裝單分子，該等自我組裝單分子間隔地形成於該 導電層之一表面。該橋接層具有複數個橋接分子，每一橋 接分子之一端連接相對之自我組裝單分子。該甲胎兒蛋白 抗體層具有複數個甲胎兒蛋白抗體，每一曱胎兒蛋白抗體 具有一橋接端及一結合端，該橋接端連接相對橋接分子之 另一端，該結合端用以與一甲胎兒蛋白抗原結合。 136428.doc 201024727 本發明之生醫感測器之製作係結合奈米科技與微機電技 術’故元件具有較薄的厚度尺寸，所以其相速度會比大部 分的液體低，造成該生醫感測器在量測液體時因為傳遞波 速較慢’所以不會造成任何能量輻射到液體中。因此，本 發明之該生醫感測器適合於量測液體’特別是生物感測及 化學感測。 再者’因為該生醫感測器的厚度僅有幾個微米厚，且薄 板的質量密度非常低’故整個元件具有非常高的質量感測 靈敏度。因此，利用本發明之生醫感測器以檢驗血液中之 甲胎兒蛋白濃度時，其具有高準確度、高靈敏度、低操作 頻率、檢測時間短、穩定度高以及成本較低等優點。 【實施方式】 參考圖1’其顯示本發明應用於甲胎兒蛋白檢測之弩曲 平板波（Flexural Plate Wave, FPW)生醫感測器。該生醫感 測器1包括一彎曲平板波元件1 〇及一自我組裝單分子（Self_ assembly Monolayer，SAM)結構20。該彆曲平板波元件1〇 具有一内凹的空腔11、一導電層12及至少一交指式傳感器 (Interdigital transducer, IDT)13，該導電層 12形成於該空 腔11之表面，該交指式傳感器13位於該空腔11之上方相對 位置。在本實施例中’該彎曲平板波元件1〇係為一半導體 元件（如矽半導體元件）’該導電層12係為金屬層，例如： 金（Au)或鉻（Cr)/金（Au)合金。 該彎曲平板波元件10主要的設計參數為該交指式傳感器 13之電極間距、交指式傳感器電極對數、交指式傳威器電 136428.doc 201024727 極重疊長度與輸入/輸出埠（I/O)之延遲長度，並配合理論 公式之推導而求出最佳化彎曲平板波元件的中心頻率以及 質量靈敏度等重要輸出特性。另外，該彎曲平板波元件 係藉由微質量密度或黏滯係數的變化而感測出相速度的改 變，且該彎曲平板波元件10具有較薄的厚度尺寸。因此， 該彎曲平板波元件10適合於量測液體，特別是生物感測及 化學感測。 該彎曲平板波元件10的製作流程如囷2至圖5所示。參考 圖2，首先利用高溫爐管於一基板1〇1(在本實施例尹為梦 基板）之二相對側面成長5〇〇〇 A厚的二氧化梦（Si〇2)薄膜 102 ’且利用低壓化學氣體沉積系統（1〇w pressure chemical vapor deposition，LPCVD)於該二氧化矽薄膜ι〇2上沉積 1500A厚的低應力氮化矽（SiaN4)薄膜1〇3 ’再利用電子束蒸 鍍機沉積系統（E-gun evaporator)於其中一側面之該氮化石夕 薄膜103上沉積一層鉻/金薄膜1〇4。其中，該路/金薄膜1〇4 之該鉻之厚度為200A，而該金之厚度為1500人。本發明於 FPW元件10之低應力氮化矽（shN4)薄膜103上沉積鉻/金底 電極（即該鉻/金薄膜104)，以增加傳統彎曲平板波（|?1>|)元 件的穩定性與訊雜比（S/N)。 參考圖3 ’接下來利用射頻濺鍍機（RF_sputter)沉積高優 質的氧化鋅（ZnO)壓電薄膜105,再將該氧化辞壓電薄膜 105經微影及钕刻製程定義其圖形。該氧化鋅壓電薄膜1〇5 之材料具有高機電耦合係數、與基板之黏附性佳、低聲速 (低操作頻率）、環境抵抗性強、製程容易並且與積體電路 136428.doc -10- 201024727 製程相容等優點。 配合參考圖4及囷5，經旋塗與微影一層光阻1〇6 ,再利 用電子束蒸鍍機沉積鉻/金之IDT電極107，並以掀舉法 (lift-off)定義該IDT電極107，以形成一組輸入交指叉電極 131及一組輸出交指叉電極132(即，該交指式傳感器13)。 其中，該輸入交指叉電極131及該輸出交指又電極13 2係作 為該彎曲平板波元件10之輸入/輸出端子。 接著，以濺鍍方式形成該導電層12於該空腔11之表面， 以製作完成該彆曲平板波元件1 〇。另外，只要在該輸入交 指又電極131及該輸出交指叉電極132之間設置一故大器 (圖未示出）即可組成一彎曲平板波延遲線震盪器。 該交指式傳感器13係以壓電耦合效應來產生並偵測波， 其中’該輸入交指叉電極131以逆壓電效應來將加入於其 上的電訊號轉變成彈性波動來輸出，此一彈性波經週一段 延遲時間後’將接觸到該輸出交指又電極132，並以正壓 電效應來將所接收到的彈性波轉變成交流訊號來輸出，而 輸出訊號的振幅及相位取決於該交指式傳感器13的幾何形 狀。該放大器係用以放大該彈性波。該彈性波衰減的改變 係由於黏性的變化被該輸出交指叉電極132反映在信號幅 度之變化上。其中，該彎曲平板波元件1〇較佳之操作頻率 在1〜10 MHz之間。 較佳地’該彎曲平板波元件10可另包括二反射結構14， 設置於該交指式傳感器13之二側（如圖6所示）。其中，當一 電壓訊號傳遞至該輸入交指叉電極13丨或該輸出交指叉電 136428.doc -11- 201024727 極132並且經由歷電效應轉換成表面聲波之後，所產生的 表面聲波會往該輸入交指又電極131或該輸出交指又電極 132二側邊傳遞，如此一來該輸入交指又電極13ι或該輸出 交指又電極132所能接收到的能量就只剩下原來的1/2，而 另外1/2的能量就從該輸入交指又電極丨31或該輸出交指又 電極132之另一側邊消散掉’這樣所能接收到的能量至少 會有3dB的損耗。 為了讓能量的損耗降到最低’故於該交指式傳感器13之 二側設置該等反射結構14，在本實施例中，該等反射結構 14間之距離設計為傳遞波長的20倍長度，以增加其反射係 數’讓原本耗損的能量經由反射再利用，以減少能量的損 失並增加感測靈敏度。 再參考圖1 ’該自我組裝單分子結構20設置於该空腔 11，其包括：一自我組裝單分子層21、一橋接層22及一甲 胎兒蛋白抗體（Alpha-fetoprotein，AFP)層23。其中，該自 我組裝單分子層21係形成於該導電層12之表面，其具有複 數個自我組裝單分子211，該等自我組裝單分子211間隔地 开> 成於該導電層12之表面。其卞，該等自我組裝單分子 211係藉由各相鄰分子間之氫鍵、離子鍵或凡德瓦力，以 整齊地自我排列形成於該導電層12之表面。在本實施例 中’該自我組裝單分子層21係為耽胺酸（cystamine)。 該橋接層22具有複數個橋接分子221，每一橋接分子221 之一端連接相對之自我組裝單分子211。在本實施例中， 該橋接層22係為戊二路（giutaraidehyde)。 136428.doc •12· 201024727 圖7顯示本發明自我組裝單分子層之甲胎兒蛋白抗體結 合甲胎兒蛋白抗原之示意圖。配合參考圖1及圓7,該甲胎 兒蛋白抗體層23具有複數個甲胎兒蛋白抗體231，每一甲 胎兒蛋白抗體231具有一橋接端232及一結合端233，該橋 接端232連接相對橋接分子221之另一端，使得每一曱胎兒 蛋白抗體實質上係呈Y字形，該結合端233用以與一甲胎兒 蛋白抗原30結合。 以下茲詳細說明本發明自我組裝單分子結構20形成於該 導電層12表面之步驟： (1) 硫金鍵結··將彎曲平板波元件10浸於濃度20 mM的 胱胺酸溶液中反應1小時，再以去離子水（Di-Water) 洗淨，之後乾燥形成自我組裝單分子層21。 (2) 進行橋接：將弩曲平板波元件1〇浸於戊二醛溶液中 反應1小時，再以去離子水洗淨，之後乾燥形成橋接 層22 〇 (3) AFP抗體層鍵結：將AFP抗體溶液5 μι滴於金電極 上，在溫度37。(：與相對濕度100%RH環境下作用1小 時’再以清潔液（wash buffer)、麟酸鹽緩衝液 (phosphate buffered saline，PBS)及去離子水清洗， 之後乾燥形成甲胎兒蛋白抗體層23。 (4) 填補抗體空餘位置：將牛血清蛋白（b〇vine serum albumin, BSA)溶液20 μι滴於該弩曲平板波元件之導 電層表面，反應30分鐘，以增加該等AFP抗艘與AFP 抗原之專一性結合度，再以清潔液、磷酸鹽緩衝液 136428.doc •13- 201024727 及去離子水清洗，之後再進行一乾燥步驟β 其中，檢測時係將AFP抗原血清5叫滴於該弩曲平板波 元件10之該導電層12表面’在溫度37。^、相對濕度 (RH)l〇〇%環境下作用1小時，隨後以清潔液、磷酸鹽緩衝 液及去離子水清洗，之後將該彎曲平板波生醫感測器j放 置常溫下乾燥後’最後測量該彎曲平板波生醫感測器1之 頻率’即可測得該AFP抗原血清中之AFP抗原之濃度。經 0 實際量測結果顯示’其線性範圍為12〜6〇〇 ng/ml(即1 〇〜5〇〇 IU/ml)，涵蓋肝癌檢測所需範圍2〇〜4〇〇 ng/ml(即 16.6〜333.3 IU/ml)，因此極適合用來當作肝癌感測器之應 用。 本發明之生醫感測器1之製作係結合奈米科技與微機電 技術’故元件具有較薄的厚度尺寸，所以其相速度會比大 部分的液體低（一般液體中聲波速度為9〇〇〜1500 m/s)，造 成該生醫感測器1在量測液體時因為傳遞波速較慢，所以 φ 不會造成任何能量輻射到液體中。因此，本發明之該生醫 感測器1適合於量測液體，特別是生物感測及化學感測。 再者’因為該生醫感測器1的厚度僅有幾個微米厚，且 薄板的質量密度非常低’故整個元件具有非常高的質量感 測靈敏度。因此’利用本發明之生醫感測器1以檢驗血液 中之甲胎兒蛋白濃度時，其具有高準確度、高靈敏度、低 操作頻率、檢測時間短、穩定度高以及成本較低等優點。 本發明選擇具有高優值特性之氧化鋅（Zn0)作為彎曲平 板波元件10之壓電層，並且本發明結合生物科技之自我組 136428.doc -14· 201024727 裝單分子（SAMs)技術與微機電系統（MEMS)技術，提出一 種創新的且具進步性（有底電極設計）的彎曲平板波生醫感 測器’以應用在肝癌病患血清中甲胎兒蛋白濃度值之檢 測。 惟上述實施例僅為說明本發明之原理及其功效，而非用 以限制本發明。因此，習於此技術之人士對上述實施例進 行修改及變化仍不脫本發明之精神。本發明之權利範圍應 如後述之申請專利範圍所列。 【圖式簡單說明】 圖1顯示本發明應用於甲胎兒蛋白檢測之弩曲平板波 (Flexural Plate Wave ’ FPW)生醫感測器之示意圖； 圖2至5顯示本發明彎曲平板波元件之製作步驟示意圖； 圖6顯示本發明設置二反射結構於交指式傳感器二側之 示意圖；及 圖7顯示本發明自我組裝單分子層之甲胎兒蛋白抗體結 合甲胎兒蛋白抗原之示意圓。 【主要元件符號說明】 1 本發明應用於甲胎兒蛋白檢測之彎曲平板波 生醫感測器 10 f曲平板波元件 11 空腔 12 導電層 13 交指式傳感器 14 反射結構 136428.doc -15- 201024727 自我組裝單分子結構 自我組裝單分子層 橋接層 甲胎兒蛋白抗體層 曱胎兒蛋白抗原 基板Bioelectronics, Volume 22, Issue 2, 2006, pp. 233-240. SUMMARY OF THE INVENTION The present invention provides a curved flat wave biomedical sensor for use in the detection of alpha fetal protein, comprising: a curved flat wave component and a Self-assembled monomolecular structure. The curved plate wave element has a concave cavity and a conductive layer formed on the surface of the cavity. The self-assembled monomolecular structure is disposed in the cavity, and includes: a self-assembled monolayer, A bridging layer and a layer of a fetal protein antibody. The self-assembling monolayer has a plurality of self-assembled single molecules that are formed at intervals on one surface of the conductive layer. The bridging layer has a plurality of bridging molecules, one end of each bridging molecule being linked to a relatively self-assembling single molecule. The alpha-fetoprotein antibody layer has a plurality of alpha-fetoprotein antibodies, each of the fetal protein antibodies has a bridge end and a binding end, and the bridge end is connected to the other end of the bridge molecule, and the binding end is used for a fetal protein Antigen binding. 136428.doc 201024727 The production of the biomedical sensor of the present invention combines nanotechnology and microelectromechanical technology to have a thin thickness dimension, so that the phase velocity is lower than that of most liquids, resulting in the medical sense. The detector does not cause any energy to radiate into the liquid when it is measuring the liquid because the transmission wave velocity is slower. Thus, the biomedical sensor of the present invention is suitable for measuring liquids', particularly biosensing and chemical sensing. Furthermore, since the thickness of the biomedical sensor is only a few micrometers thick and the mass density of the thin plate is very low, the entire component has a very high mass sensing sensitivity. Therefore, when the biomedical sensor of the present invention is used to test the concentration of the fetal protein in the blood, it has the advantages of high accuracy, high sensitivity, low operating frequency, short detection time, high stability, and low cost. [Embodiment] Referring to Fig. 1', the present invention is applied to a flexural plate wave (FPW) biomedical sensor for the detection of alpha fetal protein. The biomedical sensor 1 includes a curved plate wave element 1 and a Self_assembly Monolayer (SAM) structure 20. The curved plate wave element 1 has a concave cavity 11 , a conductive layer 12 and at least one interdigital transducer (IDT) 13 , and the conductive layer 12 is formed on the surface of the cavity 11 . The interdigital sensor 13 is located at an opposite position above the cavity 11. In the present embodiment, the curved plate wave element 1 is a semiconductor element (such as a germanium semiconductor element). The conductive layer 12 is a metal layer such as gold (Au) or chromium (Cr)/gold (Au). alloy. The main design parameters of the curved flat wave component 10 are the electrode spacing of the interdigital sensor 13, the number of interdigitated sensor electrodes, and the interdigitated transmitter power 136428.doc 201024727 pole overlap length and input/output port (I/) The delay length of O), together with the derivation of the theoretical formula, finds important output characteristics such as the center frequency and mass sensitivity of the optimized curved plate wave element. Further, the curved plate wave element senses a change in the phase velocity by a change in the micromass density or the viscous coefficient, and the curved plate wave element 10 has a thin thickness dimension. Therefore, the curved plate wave element 10 is suitable for measuring liquids, particularly biosensing and chemical sensing. The manufacturing flow of the curved flat wave element 10 is as shown in FIG. 2 to FIG. 5. Referring to FIG. 2, first, a high-temperature furnace tube is used to grow a 5 〇〇〇 A thick oxidized dream (Si 〇 2) film 102 ′ on the opposite side of a substrate 1 〇 1 (in this embodiment, Yin Wei Meng substrate). A low-pressure chemical vapor deposition (LPCVD) deposits a 1500A thick low-stress tantalum nitride (SiaN4) film on the yttrium oxide film ITO 2 by a 1 〇 3 're-use electron beam evaporation machine. An E-gun evaporator deposits a layer of chromium/gold film 1〇4 on the nitride film 103 on one of the sides. Wherein, the thickness of the chromium of the road/gold film 1〇4 is 200A, and the thickness of the gold is 1500 persons. The present invention deposits a chromium/gold bottom electrode (i.e., the chromium/gold film 104) on the low stress tantalum nitride (shN4) film 103 of the FPW element 10 to increase the stability of the conventional curved plate wave (|?1>|) element. Sex and signal to noise ratio (S/N). Referring to Fig. 3', a high-quality zinc oxide (ZnO) piezoelectric film 105 is deposited by an RF sputter (RF_sputter), and the oxidized piezoelectric film 105 is patterned by a lithography and engraving process. The material of the zinc oxide piezoelectric film 1〇5 has high electromechanical coupling coefficient, good adhesion to a substrate, low sound velocity (low operating frequency), strong environmental resistance, easy process, and integrated circuit 136428.doc -10 - 201024727 Process compatibility and other advantages. Referring to FIG. 4 and FIG. 5, a layer of photoresist 1 〇 6 is spin-coated and lithographically deposited, and then an IDT electrode 107 of chromium/gold is deposited by an electron beam evaporation machine, and the IDT is defined by a lift-off method. The electrodes 107 are formed to form a set of input interdigitated electrodes 131 and a set of output interdigitated electrodes 132 (i.e., the interdigitated sensor 13). The input interdigital electrode 131 and the output interdigital electrode 13 2 are used as input/output terminals of the curved flat wave element 10. Next, the conductive layer 12 is formed on the surface of the cavity 11 by sputtering to form the other curved plate wave element 1 . In addition, a curved flat wave delay line oscillator can be formed by providing a large device (not shown) between the input finger electrode 131 and the output finger electrode 132. The interdigital sensor 13 generates and detects a wave by a piezoelectric coupling effect, wherein 'the input interdigitated electrode 131 converts an electric signal added thereto into an elastic wave by an inverse piezoelectric effect, and the output After a period of delay, the elastic wave will contact the output and the electrode 132, and convert the received elastic wave into an alternating current signal by a positive piezoelectric effect, and the amplitude and phase of the output signal are determined. The geometry of the interdigital sensor 13 is used. The amplifier is used to amplify the elastic wave. The change in the attenuation of the elastic wave is reflected by the output cross-fork electrode 132 in the change in signal amplitude due to the change in viscosity. Wherein, the curved plate wave element 1 has a preferred operating frequency of between 1 and 10 MHz. Preferably, the curved plate wave element 10 may further include a two-reflection structure 14 disposed on two sides of the interdigital sensor 13 (as shown in FIG. 6). Wherein, when a voltage signal is transmitted to the input cross finger electrode 13 or the output cross finger 136428.doc -11- 201024727 pole 132 and converted into a surface acoustic wave via the calendar effect, the generated surface acoustic wave will go to The input interdigitated electrode 131 or the output interdigitated electrode 132 is transmitted on both sides of the electrode 132, so that the energy received by the input interdigitated electrode 13 or the output interdigitated electrode 132 remains only the original 1/2, and another 1/2 of the energy is dissipated from the input and the other side of the electrode 丨31 or the output of the electrode 132. The energy received can have at least 3 dB of loss. . In order to minimize the loss of energy, the reflective structures 14 are disposed on two sides of the interdigital sensor 13. In the present embodiment, the distance between the reflective structures 14 is designed to be 20 times the wavelength of the transmission wavelength. In order to increase its reflection coefficient, the originally consumed energy is reused through reflection to reduce the loss of energy and increase the sensitivity of sensing. Referring again to FIG. 1 ' the self-assembled monomolecular structure 20 is disposed in the cavity 11 and includes: a self-assembled monolayer 21, a bridging layer 22, and an alpha-fetoprotein (AFP) layer 23. Wherein, the self-assembled monolayer 21 is formed on the surface of the conductive layer 12, and has a plurality of self-assembled single molecules 211, and the self-assembled single molecules 211 are spaced apart and formed on the surface of the conductive layer 12. Thereafter, the self-assembled single molecules 211 are neatly arranged on the surface of the conductive layer 12 by hydrogen bonds, ionic bonds or van der Waals forces between adjacent molecules. In the present embodiment, the self-assembled monolayer 21 is a cystamine. The bridging layer 22 has a plurality of bridging molecules 221, one end of each bridging molecule 221 being coupled to a self-assembling single molecule 211. In this embodiment, the bridging layer 22 is a giutaraidehyde. 136428.doc • 12· 201024727 Figure 7 shows a schematic representation of the alpha-fetoprotein antibody of the self-assembled monolayer of the present invention in combination with a fetal protein antigen. Referring to FIG. 1 and circle 7, the alpha-fetoprotein antibody layer 23 has a plurality of alpha-fetoprotein antibodies 231, and each of the fetal protein antibodies 231 has a bridge end 232 and a binding end 233, and the bridge end 232 is connected to the bridge molecule. At the other end of 221, each of the fetal protein antibodies is substantially Y-shaped, and the binding end 233 is used to bind to a fetal protein antigen 30. The following is a detailed description of the steps of forming the self-assembled monomolecular structure 20 of the present invention on the surface of the conductive layer 12: (1) Sulfur-gold bonding. · Immersing the curved plate wave element 10 in a cystine solution having a concentration of 20 mM. After an hour, it was washed with deionized water (Di-Water) and then dried to form a self-assembled monolayer 21. (2) Bridging: The immersed plate wave element 1 is immersed in a glutaraldehyde solution for 1 hour, washed with deionized water, and then dried to form a bridging layer 22 〇(3) AFP antibody layer bonding: AFP antibody solution 5 μιη drops on a gold electrode at a temperature of 37. (: 1 hour in a relative humidity of 100% RH environment) and then washed with a wash buffer, phosphate buffered saline (PBS) and deionized water, and then dried to form a fetal protein antibody layer 23 (4) Filling the vacant position of the antibody: 20 μg of bovine serum albumin (BSA) solution was dropped on the surface of the conductive layer of the tortuous plate wave element, and reacted for 30 minutes to increase the AFP resistance and The specific binding degree of the AFP antigen is further washed with a cleaning solution, phosphate buffer 136428.doc •13- 201024727 and deionized water, followed by a drying step β, wherein the AFP antigen serum 5 is dropped during the test. The surface of the conductive layer 12 of the tortuous plate wave element 10 is subjected to a temperature of 37 ° C, relative humidity (RH) 10 %, and then washed with a cleaning solution, a phosphate buffer solution and deionized water. The concentration of the AFP antigen in the AFP antigen serum can then be measured by placing the curved plate wave biomedical sensor j after drying at room temperature and finally measuring the frequency of the curved plate wave biosensor 1 . Actual measurement result The linear range is 12~6〇〇ng/ml (ie 1 〇~5〇〇IU/ml), covering the range of 2肝癌~4〇〇ng/ml for liver cancer detection (ie 16.6~333.3 IU/ml) Therefore, it is very suitable for use as a liver cancer sensor. The production of the biomedical sensor 1 of the present invention is combined with nanotechnology and microelectromechanical technology, so that the component has a thin thickness dimension, so its phase velocity It will be lower than most of the liquid (the sound velocity in the liquid is generally 9 〇〇 to 1500 m / s), causing the biomedical sensor 1 to measure the liquid because the transmission wave velocity is slow, so φ does not cause any energy. Radiation into the liquid. Therefore, the biomedical sensor 1 of the present invention is suitable for measuring liquids, particularly biosensing and chemical sensing. Again, because the thickness of the biomedical sensor 1 is only a few The micron is thick, and the mass density of the thin plate is very low, so the entire component has very high mass sensing sensitivity. Therefore, it is highly accurate when using the biomedical sensor 1 of the present invention to test the concentration of the fetal protein in the blood. Degree, high sensitivity, low operating frequency, short detection time, high stability The invention has the advantages of low cost and the like. The present invention selects zinc oxide (Zn0) having high-value characteristics as the piezoelectric layer of the curved plate wave element 10, and the present invention incorporates the biotechnology self-group 136428.doc -14· 201024727 Molecular (SAMs) technology and microelectromechanical systems (MEMS) technology, propose an innovative and progressive (bottomed electrode design) curved flat wave biomedical sensor to apply the concentration of alpha-fetoprotein in serum of liver cancer patients The above-described embodiments are merely illustrative of the principles of the invention and its effects, and are not intended to limit the invention. Therefore, those skilled in the art can devise modifications and variations of the embodiments described above without departing from the spirit of the invention. The scope of the invention should be as set forth in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing a Flexural Plate Wave 'FPW biomedical sensor applied to a fetal fetal protein detection; FIGS. 2 to 5 show the fabrication of a curved flat wave element of the present invention. Figure 6 is a schematic view showing the arrangement of the two-reflection structure on the two sides of the interdigital sensor of the present invention; and Figure 7 shows the schematic circle of the alpha-fetoprotein antibody binding to the alpha-fetoprotein antigen of the self-assembled monolayer of the present invention. [Main component symbol description] 1 The present invention is applied to a curved flat wave biomedical sensor for detecting a fetal protein protein. 10 f curved plate wave element 11 cavity 12 conductive layer 13 interdigitated sensor 14 reflective structure 136428.doc -15- 201024727 Self-assembled monomolecular structure self-assembled monolayer bridge layer alpha fetal protein antibody layer 曱 fetal protein antigen substrate
二氧化矽薄膜 氮化矽薄膜 鉻/金薄膜 氧化鋅壓電薄膜 光阻Cerium oxide film tantalum nitride film chromium/gold film zinc oxide piezoelectric film photoresist
20 21 22 23 30 101 102 103 104 105 106 107 131 132 211 221 231 交指式傳感器電極 輸入交指叉電極 輸出交指叉電極 自我組裝單分子 橋接分子 甲胎兒蛋白抗體 232 橋接端 233 結合端 •16· 136428.doc20 21 22 23 30 101 102 103 104 105 106 107 131 132 211 221 231 Interdigital sensor electrode input Interdigitated electrode output Interdigitated electrode Self-assembled single molecule bridging molecule A fetal protein antibody 232 Bridge end 233 Binding end • 16 · 136428.doc