Smartphone Self-Contained NIR Colorimeter

Abstract

A self-contained smartphone-based near infrared (NIR) colorimeter is reported for the first time by utilizing the inbuilt NIR emitter ( $\Delta \lambda \approx 770 \!-\! 1000$ nm) and macrolens complementary metal-oxide semiconductor (CMOS) camera of the phone. The emitted NIR light is guided through a low-cost multimode plastic fiber to illuminate the test sample, and the phone's CMOS camera is utilized to collect and digitize the transmitted light through the sample. An easy-to-use customized Android app has been developed to operate this ultra-low-cost (<$2)>${{\lambda }_p} \approx 930$ nm, which complies with the operating wavelength band ( $\Delta \lambda \approx 910 \!-\! 980$ nm) of this instrument.