Handheld Multispectral Fluorescence Imaging System to Detect and Disinfect Surface Contamination

Abstract

Contamination inspection is an ongoing concern for food distributors, restaurant owners, caterers, and others who handle food. Food contamination must be prevented, and zero tolerance legal requirements and damage to the reputation of institutions or restaurants can be very costly. This paper introduces a new handheld fluorescence-based imaging system that can rapidly detect, disinfect, and document invisible organic residues and biofilms which may host pathogens. The contamination, sanitization inspection, and disinfection (CSI-D) system uses light at two fluorescence excitation wavelengths, ultraviolet C (UVC) at 275 nm and violet at 405 nm, for the detection of organic residues, including saliva and respiratory droplets. The 275 nm light is also utilized to disinfect pathogens commonly found within the contaminated residues. Efficacy testing of the neutralizing effects of the ultraviolet light was conducted for Aspergillus fumigatus, Streptococcus pneumoniae, and the influenza A virus (a fungus, a bacterium, and a virus, respectively, each commonly found in saliva and respiratory droplets). After the exposure to UVC light from the CSI-D, all three pathogens experienced deactivation (> 99.99%) in under ten seconds. Up to five-log reductions have also been shown within 10 s of UVC irradiation from the CSI-D system.

Surface Environment and Energy Density Effects on the Detection and Disinfection of Microorganisms Using a Portable Instrument

“…In addition, the size limit of detectable contaminant was determined to be about 0.15 mm for a single colony on an agar plate. Similarly, Sueker et al [ 28 ] reported that the minimum detectable spot size for saliva and respiratory droplets on stainless steel plates was about 0.13 mm, using a CSI-D device (a previous model of CSI-D+). These limitations, such as detectable concentrations or spot size, are also affected by the measurement parameters, such as working distance and angle of incidence of the excitation light.…”

“…Some systems focus on the disinfection of individual items within a container or room, while others are designed to irradiate large areas of interest with multiple UV bands. Ideally, these systems should provide disinfection capability with multiple bands while maintaining portability [ 28 ]. A recent report utilizing the CSI-D+ device (also used in this study) demonstrated simultaneous fluorescence-based detection and UV-based sterilization capability in a single battery-operated unit.…”

“…However, the effect of various confounding factors, such as the type of a substrate or an effective energy dose, are still unclear, and only a few publications thoroughly investigate the disinfection process using handheld instruments [ 23 , 29 ]. Compared to Sueker et al [ 28 ], this work focuses on expanding the applicability of the proposed instrument in surface contamination detection and disinfection. This was accomplished by preparing samples containing multiple types of microorganisms and utilizing multiple types of surfaces that may be found in food processing facilities or hospitals.…”

Cleanliness assessment in long-term care facilities using deep learning and multiwavelength fluorescence imaging

“…In a previous study, we have demonstrated detection of invisible human saliva and respiratory droplets on stainless steel and plastic surfaces 22 . A secondary capability is to provide immediate spot disinfection using the UVC germicidal effect when residual contamination is discovered during audits.…”

Combining deep learning and fluorescence imaging to automatically identify fecal contamination on meat carcasses

“…In this study, we employ a fluorescence imaging device developed by SafetySpect and two state-of-the-art deep learning algorithms, including EfficientNet and U-Net, to first discriminate the video frames with fecal residue on meat surfaces and then accurately segment and identify the corresponding areas of fecal contamination in the image. The handheld automated imaging inspection device (CSI-D), created by SafetySpect 13 , offers mobility and flexibility for fluorescence-based contaminant detection on both food products (e.g., carcasses) and equipment surfaces in meat processing facilities under bright ambient light. Visualization by fluorescence emission has excellent potential for food safety procedures.…”