Imaging of Chemical Reactions Using a Terahertz Chemical Microscope

• Main Authors: Toshihiko Kiwa, Tatsuki Kamiya, Taiga Morimoto, Kentaro Fujiwara, Yuki Maeno, Yuki Akiwa, Masahiro Iida, Taihei Kuroda, Kenji Sakai, Hidetoshi Nose, Masaki Kobayashi, Keiji Tsukada
• Format: Article
• Language: English
• Published: MDPI AG 2019-01-01
• Series: Photonics
• Subjects: terahertz; chemical reaction; bio-related materials; femtosecond laser; imaging; ion; immune reactions; antibody; antigen
• Online Access: https://www.mdpi.com/2304-6732/6/1/10

This study develops a terahertz (THz) chemical microscope (TCM) that visualizes the distribution of chemical reaction on a silicon-based sensing chip. This chip, called the <i>sensing plate</i>, was fabricated by depositing Si thin films on a sapphire substrate and thermally oxidizing the Si film surface. The Si thin film of the sensing plate was irradiated from the substrate side by a femtosecond laser, generating THz pulses that were radiated into free space through the surface field effect of the Si thin film. The surface field responds to chemical reactions on the surface of the sensing plate, changing the amplitude of the THz pulses. This paper first demonstrates the principle and experimental setup of the TCM and performs the imaging and measurement of chemical reactions, including the reactions of bio-related materials.