Thermoelectric and Photoinduced Properties of Thin-film Flexible Photo Sensors Formed by Drying Carbon Nanotube Dispersion

Capturing changes in chemical substances in plants and animals is essential for understanding biological activities. Optical sensing technologies, which enable non-invasive detection, have been actively studied. Conventional optical sensors rely on silicon or compound semiconductor photodiodes, but challenges remain in their miniaturization and flexibility. We developed a carbon nanotube dispersion film sensor using a carbon nanotube dispersion liquid. Carbon nanotubes are promising for optical sensing due to their photoresponsiveness based on the photoelectric effect, as well as their flexibility and high electrical mobility. In this study, we fabricated a carbon nanotube dispersion film sensor and proposed a circuit model to describe its thermal and optical responses. A measurement system was also developed to evaluate these characteristics. Results showed that the sensor's response depends on temperature and light intensity. By compensating for the temperature-dependent response, good linearity as an optical sensor can be achieved. This study demonstrates the feasibility of a simple, low-cost, compact, and flexible optical sensor. Its potential for optical sensing could aid in elucidating chemical dynamics in plants and animals of diverse shapes and sizes.