Prof. Takashi Tokuda of the Graduate School of Materials Science at the Nara Institute of Science and Technology (NAIST) in Japan, talks to us about the work behind the paper ‘CMOS sensor-based palm-sized in-line optical analysis device for microchemistry systems’, page 1222. Prof. Takashi Tokuda I have been developing CMOS-based novel sensors for new applications in bioscience, chemistry, and medicine with Prof. Jun Ohta here at NAIST. In this particular case, we had an idea to realise polarisation detection using a monolithically embedded wire grid polariser, made with a metal layer, in standard CMOS processes. We can realise polarisation imaging without any post-fabrication process or external optics. After we demonstrated the basic functionality of the embedded polariser [reported in Electronics Letters, Vol. 45, issue 4], we knew that Prof. Kiyomi Kakiuchi, who majors in synthetic organic chemistry here, had a demand for a small-sized, in-line polarimeter to monitor his microchemistry system. We then started a collaboration which has led us to the present work. Microchemistry systems include various chemical reaction/analysing systems that take advantage of narrow channel or small-volume reactors. They include the concept of micro total analysis systems (µ-TAS). We think our CMOS sensors with polarisation detection (and other functionality) can be a good solution for in-situ monitoring in microchemistry systems. We can integrate various sensing functionalities, including light detection for absorption measurement, polarisation detection for chirality monitoring and other electric and electrochemical sensing on a small sensor. As a future work, we have an idea for direct integration of the CMOS multifunctional sensor into various microchemistry systems. In the paper, we developed a palm-sized in-line optical analysis device. We demonstrated its functionality to simultaneously measure polarisation rotation and absorption of a chemical solution. The device is equipped with our polarisation-analysing CMOS image sensor. We realised a volume of the in-line optical analysis device as small as 1/1000 of a typical desktop polarimeter. The in-line optical analysing device presented in this paper does not have any mechanical rotating optics. Furthermore, we integrated a capability of single-wavelength absorption measurement. These features originate in the functional flexibility of our polarization-analysing CMOS image sensor. From the viewpoint of CMOS image sensor technology, the embedded polariser within CMOS process is a good strategy for polarisation detection especially in more advanced processes, thus we expect more work in this will appear in the future. The integration of the CMOS-based small and multifunctional sensor is another interesting and promising topic. Although it is in a stage of proof-of-concept, it is expected to be a powerful monitoring solution for high-performance microchemistry systems in the future. This work was performed in projects supported by a grant-in-aid from the Japan Society for the Promotion of Science. It is also a part of our research activity to pursue new CMOS-based intelligent sensors. Our research interests cover not only optical detection, but also various multifunctional sensing schemes. We are also working on CMOS-based neural sensing/interfacing technologies. We are developing various sensors and other devices using the surface of CMOS chips as novel functional surfaces. We think that our approach to use the CMOS electronics more directly for biological, chemical and medical applications could become one of the next trends of the research field. We expect more researchers to join this field and many CMOS-based unique sensors/functional devices will be proposed and demonstrated. We hope a new industrial market will be born from this field.