生物延迟发光辐照光源系统研制

Development of biological delayed luminescence irradiation source system

针对目前生物延迟发光检测系统利用外置激发光源存在的延迟误差和自然光叠加干扰导致的测量结果重复性不好和可靠性差的问题,设计了一种生物延迟发光辐照光源系统。该光源系统主要由恒温辐照室、三基色RGB-LED(light-emitting diode)矩阵辐照光源、电子快门隔离器及控制电路组成,并与BPCL系列微弱发光测量仪组装在一起使用。在51系列单片机的控制下,该辐照光源系统实现了光源频率和光强的多重选择以及辐照时间的程序化操作,实现了光照与检测之间在同一个暗室通道中通过电子快门的迅速切换,极大的降低了自然光的叠加干扰与延迟误差。背景噪声和稳定性试验测试结果表明,应用该系统使平均光子计数的噪声偏差不超过4.5 cps,5次重复测试的相对误差为0.7%,重复测试的延迟发光曲线具有良好的重合度。对萌发玉米延迟发光的测试结果表明,延迟发光曲线的拟合优度R2在0.99以上,应用该系统可以得到较为理想的结果。

The analysis and application of biological delayed luminescence is a hotspot in many interdisciplinary areas. However, the irradiation source of biological delayed luminescence has not been thoroughly investigated. In order to solve some problems of the current biological delayed-luminescence detection system, including the poor repeatability and reliability caused by the delay error of the external excitation light source and the superimposed interference of natural light, a biological delayed-luminescence irradiation source system is presented in this paper. This irradiation source system mainly consists of a constant temperature irradiation chamber, a tricolor RGB-LED matrix irradiation light source, an electronic shutter isolator, and a control circuit. The irradiation source system is assembled with the BPCL Series weak luminescence meter. The proposed system has technical improvements in three aspects related to the external excitation light source. 1） It features multiple automation selections in irradiation frequency, irradiation intensity, and programmable irradiation timing. Under the control of the MCS-51 single-chip microcomputer, 16 light spectra with varying chrominance can be selected in the range of 410-625 nm, with LED driving current adjustable from 16-40 mA for different brightness, and the irradiation time is adjustable within the range of 0-999 s. 2） It features fast switching of the electronic shutter in lighting and detection process in the same channel of a darkroom. When the light source is on, the shutter is closed automatically. During measurement, the shutter is opened automatically when the light source is off. It therefore reduces the superimposed interference with natural light and the delay error. 3） Because of the temperature sensitivity of the biological delayed luminescence, a temperature sampling circuit called the ‘single integral type A/D converter’ with a simple structure is designed based on the working principle of the‘double integral type A/D converter’. Combining with the MCU, this temperature-sampling circuit works as a temperature controller, which can maintain a constant temperature in the sample chamber. After using this irradiation source system, the results of the background noise and stability testing showed that the noise deviation in average photon counting was less than 4.5 cps （counts per second）. The relative error in five repetitive tests was 0.7%, achieving a high repeatability of the delayed luminescence curves. The test results of the delayed luminescence in germinating corn further showed that the R2 of the delayed luminescence curves fitting was greater than 0.99. Good reliability and repeatability can be achieved in this system.