The Compact Color Biofinder, an imaging device developed by researchers at the University of Hawai’i at Manoa, demonstrated the ability to detect biofluorescence signals from trace amounts of organic matter from a distance of a few centimeters to 5 m. According to Sonia Rowley, a biologist on the development team for the Biofinder, the device’s capabilities enable accurate and noninvasive detection of contaminants such as microbes or extraterrestrial biohazards that come to or from Earth. The Biofinder’s capabilities would be critical for NASA’s Planetary Protection program, Rowley said. Since 2012, a team has worked to prepare the Biofinder to rapidly detect biological materials within the context of planetary exploration and the search for extraterrestrial life, both living and extinct. The Biofinder is a portable instrument that is operated using a 24-V battery and laptop. It uses a compact, solid-state, conductively cooled Nd:YAG nanosecond pulsed laser that provides two simultaneous wavelengths, 355 nm and 532 nm, for fluorescence excitation. Most biological materials, for example amino acids, fossils, and bioresidues, have strong fluorescence signals with lifetimes of less than 20 ns. The Biofinder detects the fluorescence of organic materials and locates them over a large area at a video speed of 20 fps. The video speed is synchronized with the laser repetition rate of 20 pulses per second. To record the short-lived fluorescence signals from organic and biological materials, the Biofinder detector is gated for its shortest exposure time, which is 1 µs. Short detection time is helpful in blocking long-lived mineral phosphorescence signals and background noise. Biofinder detection of biological residues in a fish fossil: (a) white light image of a Green River Formation fish fossil; (b) fluorescence image of the fish fossil obtained by the Biofinder. Courtesy of Misra et al., 2022. The Biofinder has also demonstrated the ability to distinguish between mineral phosphorescence and organic fluorescence from standoff distances in daylight conditions and within short measurement times. The Biofinder discriminates between different types of organic materials by taking color images. “At present, there is no other equipment that can detect minute amounts of bioresidue on a rock during the daytime,” said Anupam Misra, lead instrument developer and researcher at the Hawai’i Institute of Geophysics and Planetology at the University of Hawai’i Manoa School of Ocean and Earth Science and Technology. The researchers used fossils from the Green River Formation, a tens of million-years-old fossil bed, to test the instrument’s ability to detect biomarkers in long-extinct species. The Biofinder screened through 35 fish fossil specimens in their original rock matrix from a distance of 50 cm to look for signs of biological remains. Fluorescence images taken by the Biofinder instrument showed that the fish fossils analyzed from the Green River Formation (Eocene period, 56.0 million to 33.9 million years) still contain considerable amounts of biological residues. The researchers used spectroscopic and microscopic methods to confirm the results from the Biofinder fluorescence imagery. The researchers said that fluorescence microscopes and examination under UV illumination have been used in the past to investigate fossils, but these methods have difficulty performing in situ detection in daylight and are unable to remove interference from mineral phosphorescence signals. “The Biofinder works from a distance of several meters, takes video, and can quickly scan a large area,” Misra said. These capabilities could help an exploration rover to identify objects of interest in the search for life beyond Earth. Characterization techniques, such as Raman or laser-induced breakdown spectroscopy, could then be used to determine the molecular and elemental composition of the selected objects. “If the Biofinder were mounted on a rover on Mars or another planet, we would be able to rapidly scan large areas quickly to detect evidence of past life, even if the organism was small, not easy to see with our eyes, and dead for many millions of years,” Misra said. Misra and his colleagues are applying for the opportunity to send the Biofinder on a NASA mission. The research was published in Scientific Reports (www.doi.org/10.1038/s41598-022-14410-8).