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Introduction of Electrochemistry （ 電化學簡介）

Introduction of Electrochemistry （ 電化學簡介）. Electrochemical technique is a type of bio-sensing method. Basis of Electrochemistry. Entropy (S) Definition of Entropy : the amount of randomness , or molecular disorder , in a system. Example: ice water steam

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Introduction of Electrochemistry （ 電化學簡介）

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  1. Introduction of Electrochemistry（電化學簡介） Electrochemical technique is a type of bio-sensing method.

  2. Basis of Electrochemistry

  3. Entropy (S) Definition of Entropy: the amount of randomness, or molecular disorder, in a system. Example: icewater steam Less disorder ---------------> More disorder Lower entropy -------------> Higher entropy

  4. Entropy change (∆S) ∆S = Sfinal - Sinitial If ∆S is positive, the system has become more random. If ∆S is negative, the system has become less random.

  5. Spontaneity of Reaction Reaction: a chemical or physical change Two factors that determine the spontaneity (自發性）of a reaction in a system: (1) a release or absorption of heat (∆H), (2) an increase or decrease in molecular randomness (∆S).

  6. Gibbs Free-Energy Change (∆G) ∆G = ∆H - T ∆S Free-energy change Entropy change Temperature Heat of reaction G > 0 Non-spontaneous reaction G < 0 Spontaneous reaction

  7. Potential Energy G = - n F E G > 0 Non-spontaneous reaction G < 0 Spontaneous reaction G is free energy change. E is applied voltage. F is Faraday constant n is number of mole

  8. Chemical Reactions

  9. Example of a spontaneous reaction Glucose+O2 Gluconic acid+H2O2 GOX: Glucose Enzyme Example of a non-spontaneous reaction H2O2 O2+2H++2e- Potential Examples ofElectrochemical Reactions GOx

  10. Oxidation and Reduction Oxidation reaction A  A+ + e- Reduction reaction A + e- A-

  11. Role of Enzyme in Chemical Reactions

  12. What is Biosensor? A biosensor is normally defined as a device incorporating a biological molecular recognition component connected to a transducer which can output an electronic signal that is proportional to the concentration of molecule being sensed. Donal Leech, Chemical Society Reviews, 1994, 205-213.

  13. Components of Biosensor a) Biocatalyst - converts the analyte into product. b) Transducer - detects the occurrence of the reaction and converts it into an electrical signal. c) Amplifier - amplifies the usually tiny signal to a useable level. d) Microprocessor - signal is digitized and stored for further processing, e) Display - usually need a real-time display of the analyte concentration.

  14. Analytes vs. Recognition Elements

  15. Working electrode Glucose oxidase (ox) H2O2 Glucose e- Gluconic acid Glucose oxidase (red) O2 Analyte, Biocatalyst, and Product

  16. Transducer Electrochemical Cell

  17. Electrochemical Cell • Working electrode (WE) : 電化學反應進行的位置 • Reference electrode (AE) : 工作電極之電位參考點 • Counter electrode (CE): Cell 必須維持電中性，使用CE維持cell的電中性。

  18. DisplayCyclic Voltammetry (CV) • Voltage • Scan rate (V/s) • cycle Redox couple

  19. CV訊號 例一 受測溶液: 黃血鹽 掃描電位：-1v ~ 1v 掃描速率：0.1 v/sec 掃描時間：20秒

  20. CV訊號 例二 受測溶液: H2O2 掃描電位：-1v ~ 1v 掃描速率：0.1 v/sec 掃描時間：20秒

  21. RS-232 電化學 電路區塊圖 指令和訊號傳輸系統 電解槽 CE RE WE Communications of Command and Signal

  22. GUI and Display

  23. Product Examples of Electrochemical Biosensor

  24. Glucose Measurement Measurement of glucose in blood using an enzyme assay Glucose Meter

  25. Commercial Glucose Meter

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