Biospeckle laser aplicado na identificação de atividade biológica em fluido de corte de base vegetal miscível em água

Abstract

Biospeckle laser is a phenomenon that has been used as a technique in a broad range of segments, and its effectiveness has been confirmed in sectors such as medicine, agriculture and the chemical industry. The ability to non-invasively detect small changes over time in biological and non-biological samples, has proven to be a valuable aspect for the observation and analysis of certain phenomena. Therefore, experiments and research have been carried out for the detection of microorganisms in different media using the Biospeckle laser as a measurement tool. In the metalworking industry, cutting fluids (CF), which supports the chip transport, cooling and lubrication functions between the tool and the workpiece material, are highly susceptible to bacterial contamination. Developing methods of early detection of contamination by these agents is a constant concern of the productive sector. By applying image processing techniques, we can extract information on the presence of bacteria through mathematical models using Biospeckle laser to assist in monitoring CF conditions. This work aimed to evaluate the feasibility of Biospeckle laser to identify the biological activity of bacteria in water-miscible plant-based cutting fluid, in this case plant-based synthetic ester. To achieve this objective, a strain of Staphylococcus Capitis bacteria was used, a strain which is commonly found in FC. An induced contamination was carried out, and to determine the level of contamination, a score level was established through a solid medium seeding method. The contamination levels of the saline solutions were registered, with their values expressing colony forming units per milliliter (CFU/mL). Different emulsion concentrations of water and oil were prepared and illuminated with laser (Light Amplification by Stimulated Emission of Radiation). The same procedure was carried out with a control sample, a saline solution free of induced contamination. The patterns acquired through a digital microscope were posteriorly analyzed by a mathematical model and the results compared using the Tuckey model with a 5% significance level.The Biospeckle Laser Technique presented favorable results as a means to identify biological activity for the tree types of solutions studied.