應用發光二極體架設多頻率奈秒螢光生命週期量測儀器

Abstract

螢光生命週期為一具有高度可依賴性且高即時性之螢光訊號並已被應用於許多生物物理及生醫光電領域之研究。相較於以往螢光生命週期量測系統之雷射光源，發光二極體在價格以及體積上具有不可取代之優勢。本研究利用發光二極體之特性開發出一套以多色發光二極體作為激發光源之頻率域模式螢光生命週期量測系統。為了解析奈秒等級之螢光生命週期訊號，本論文將高功率發光二極體提升至可用之調變深度及調變頻率，同時，本研究開發之量測系統包含單頻率及多頻率之模式，並配合本研究中設計之發光二極體驅動電路提升系統整體準確性。本研究並利用發光二極體可快速切換不同波長之激發光之特性，量測不同波長激發下的綠藻細胞葉綠素螢光生命週期，取得即時量測之螢光生命週期及螢光光強的葉綠素螢光動態曲線。未來可將本論文開發之多色且多頻率之螢光生命週期量測系統應用於多目標之螢光生命週期動態觀測研究。

Fluorescence lifetime signals have been widely used in bio-physics and biophotonics research. With the advance of light emitting diode (LED) technology, it has been demonstrated that there are several advantages to apply LEDs as the light source of a fluorescence lifetime system: i.e. cost, size, etc. In this thesis, I’ve developed a dual-color dual-frequencies fluorescence lifetime system based on directly-modulated LED. I modulated different color of LED dice located on the same chip at different radio frequencies, in order to acquire the nanosecond lifetimes of two different fluorescent species simultaneously. I designed a modulation circuit based on a field-programmable gate array (FPGA), which provided dual-frequencies to the high power LEDs with sufficiently high modulation depth to resolve nanosecond fluorescence lifetimes. In addition, as LED has fast switching time, I applied the dual-frequency fluorescence lifetime system to measure chlorophyll a fluorescence signals of green algae cells under different wavelength of illumination in real time. By switching between different color of LED dice, the dynamic decay curve of chlorophyll a fluorescence lifetime and fluorescence intensity were acquired simultaneously. The system developed in this thesis can be applied to measure real time dynamics of fluorescence lifetimes under different excitation wavelengths.