Real-Time in Vivo Imaging of Intra-Stem Ion Distribution Using Insertable CMOS Sensor for Plants

We report the world-first result of visualization of intra-stem ion dynamics of living plants using a novel ion image sensor. A dedicated ion image sensor that can insert to the plant stem was fabricated. The sensor has
$128\times 32$
ion-sensitive pixels to capture the ion distribution reflecting the structure of the stem (vascular bundle). Imaging results showed that hydrogen ions moved from the bottom to the top of the stem due to natural transpiration. Ion distribution reflecting the vascular bundle was also clearly visualized and confirmed to correspond with the plant stem cross-sectional structure. This sensor can be used to observe the activity of photosynthesis and possibly maximize production efficiency in agriculture.