Abstract
We use Poly (3-octylthiophene-2,5-diyl) to serve as sensing material and producing a high porous density vertical diode by blade coating process to detect ammonia. The ammonia gas sensor in air background sensing system can detect the ammonia concentration from 100 part per billion (ppb) to 1 part per million (ppm) with good resolution. Besides, we try many ways to enhance the sensing system’s reliability. For example, utilizing the gastight syringe to avoid the electric signal noise during gas injection. And we also investigate how to collect human breath properly, thus sensing system can detect breath-ammonia without disturbing by the high humidity in breath or the variation of background flow. In addition, high-end measurement instrument is replaced by a microprocessor, which computes ammonia sensor’s voltage signal to identify the ammonia concentration to miniaturize sensing system. The miniaturized portable ammonia sensing system has many advantages such as non-invasive sensing, real-time sensing, low-cost and room temperature operation.