利用電漿光譜技術之手機式金屬離子檢測裝置之建立

Abstract

常壓下微電漿不需要真空系統，且因電子密度和能量密度高而具有局部高反應性，近年來有越來越多微電漿相關的研究。此外，因為電漿具有激發而放光的特性，常利用光譜來分析電漿的資訊。 本研究即是結合微電漿系統與光譜做出對於液體中金屬成分之定性以及定量分析，並利用設計過之電池驅動直流電路以及手機平台光譜儀，使整個系統成為完全的可攜式裝置，不僅有成本低的優點，也藉由可攜式電漿裝置使電漿不再只是以往受限於實驗室中的檢測，可以被更多人關注、被更多人拿來應用於生活周遭的問題上。 本研究之微電漿系統直接以待測物作為其中一個電極並在兩電極間施加高壓，因瞬間高溫將待測物汽化並受到加速電子撞擊而產生電漿。其中，金屬原子被激發後會放出不同顏色的光，這些特徵光由於能量上的差異而具有不同的波長。經由光譜儀收取電漿產生的激發光後分光，得到波長對光強度的光譜圖再加以比對分析而可檢測待測物中的元素。本研究透過改變不同的條件以及裝置的設計，達到較穩定隨時間變化之光譜與較強金屬特徵光的實驗結果，有利於金屬的定量分析。 本研究所設計之手機平台光譜儀，利用手機的相機取代光譜儀的感光元件，使光源通過特殊微結構之光柵，於表面繞射後分離不同波長的光再經由手機相機拍照，得到的分光照片經由程式分析及運算可以將照片轉換至波長對光強度作圖，雖然解析度不會超越實驗室中精密光譜儀但依然有半高寬在10奈米以內的解析度。因為現今社會中人手一台手機的狀況，利用此手機平台光譜儀會讓整體操作更方便且更容易上手，而且只要在手機上裝設微電漿裝置即可達到隨拍隨測重金屬的優點，若將整體系統達到簡單、對使用者友善(user-friendly)的操作條件後，將此微電漿應用商品化的目標則更有機會實現。

Since atmospheric microplasma system does not need vacuum system, and has unique properties such as high electron density, high power density, highly reactive environment in a local area, and light emitted from plasma, there are lots of efforts made on microplasma-related research and accompanied with optical emission spectroscopy (OES) recently. In this thesis, the combination of pin-to-water microplasma system and OES analysis is studied for qualitative and quantitative detection of metallic ions in aqueous solution. By using the designed battery-driven DC circuit and the phone-based spectrometer, the device can be thoroughly portable and low-cost. With the advantages, the portable plasma system is not only used for in-situ analysis in laboratory, but it also get more attentions from people and have more applications in our daily life. In the system, the aqueous solution contained metallic ions is directly served as one electrode, and we apply high voltage between two electrodes. When the plasma is ignited, temperature rises instantly and vaporizes the solution into plasma area. Vapor from solution is collided with accelerated electrons and then emit light in a spectrum characteristic of the gas being excited. The light emitted from plasma will have many different colors due to the differences in excitation energy of metallic atoms. Therefore, spectrometer disperses the light with wavelengths and gets spectrum which will be used to detect components in solutions. By changing the design of device and electrodes arrangements, we get more reliable results about time-resolved spectrum and stronger characteristic peaks of metallic emission to do quantitative analysis in our system. Our designed phone-based spectrometer replaces CCD with camera in mobile phone, and uses grating with particular microstructure to disperse light with different wavelength. After taking pictures of dispersion, the data will be processed by designed program code and transform pixel number of pictures into wavelength to obtain the relationship between .wavelength and light intensity. Although the resolution of phone-based spectrometer is not better than of laboratory-scale spectrometer, the FWHM (full width at half maximum) of a characteristic peak is still below 10 nm that the resolution is good enough to deal with lots of situation. Moreover, smart phones are now so commonplace that if we improve our operating system to more user-friendly and convenient way, we can achieve the goals to commercialize our research and detect metallic ions at any time and any places.