Development of a Smartphone-Based Metallic Ion Detection Device Using Plasma Emission Spectroscopy
Date Issued
2016
Date
2016
Author(s)
Chen, Min-Chun
Abstract
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.
Subjects
microplasma
spectrum
characteristic peaks
metallic ion
phone-based spectrometer
Type
thesis
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