Devabhaktuni Sandeep, Prasad Shalini
Department of Electrical and Computer Engineering, Portland State University, Portland, OR-97201, USA.
J Nanosci Nanotechnol. 2009 Nov;9(11):6299-306. doi: 10.1166/jnn.2009.1354.
In this paper we present the design, fabrication and development of an optical, label free chemical sensor technology based on the portable "lab-on-a-chip" format. This sensor technology employs the use of nanotextured thin film surfaces packaged in a stacked vertical array format functioning as organic light emitting diodes (OLED's). The intensity of emitted light from OLED's is modulated as a function of the analyte concentration. The OLEDs were fabricated in a layer by layer configuration with an indium tin oxide anode and an aluminum cathode and TPD as a hole transport layer and AIQ3 as an electron transport layer. ITO/TPD/AlQ3/Al sandwich OLEDs were converted into sensors by converting the cathode (Al) surface into an active sensing area. The prototype sensor performance was evaluated in the detection of two aliphatic hydrocarbons-ethanol and methanol. The detection sensitivity was found to be in the lower parts per million (ppm). The limit of detection for ethanol was 1 ppm and that for methanol was 10 ppm. Chemical detection was achieved upon the comparison of turn-on voltages and the intensities of the output light from the OLED when chemical was being injected onto the cathode surface, with that of a standard OLED turn-on voltage and intensity. The modulation in these two parameters with respect to the standard was determined as a measure of detection of the two chemical species.
在本文中，我们介绍了一种基于便携式“芯片实验室”形式的光学、无标记化学传感器技术的设计、制造和开发。这种传感器技术采用以堆叠垂直阵列形式封装的纳米纹理薄膜表面，其功能类似于有机发光二极管（OLED）。OLED发出的光强度会根据分析物浓度进行调制。OLED采用逐层配置制造，有氧化铟锡阳极、铝阴极，TPD作为空穴传输层，AlQ3作为电子传输层。通过将阴极（Al）表面转变为活性传感区域，将ITO/TPD/AlQ3/Al三明治结构的OLED转换为传感器。在检测两种脂肪族碳氢化合物——乙醇和甲醇时，对原型传感器的性能进行了评估。发现检测灵敏度处于百万分之几（ppm）的较低水平。乙醇的检测限为1 ppm，甲醇的检测限为10 ppm。当将化学物质注入阴极表面时，通过比较OLED开启电压和输出光强度与标准OLED开启电压和强度，实现化学检测。将这两个参数相对于标准的调制确定为检测这两种化学物质的一种度量。
