Principles or standards for automatic colony counters

The automatic colony counting instrument has been gradually loved by more and more research institutes and health control departments because of its high degree of automation, analysis results can be checked, and sample information can be retained. How to choose a type to get a colony counter with excellent performance and achieve high cost performance? This has to be explained from the principle of this type of instrument. All automatic colony counters available in the market today are automatically counted by imaging analysis, which is composed of [imaging hardware + analysis software]. Any loss of points on any of these two contents will seriously affect the results of counting analysis. Stability.

First, the selection of imaging hardware

Imaging hardware is used to obtain clear and effective colony images for analysis counting. Today's imaging hardware is photo-imaged, scanned and imaged. The advantage of taking pictures by the camera is that the imaging speed is fast, and it can ensure that the colony image is obtained within 0.5 seconds. The advantages of taking photos by SLR camera and card machine are: auto focus, and the pixel resolution is generally higher, but the imaging takes 3 to 4 seconds. However, the Achilles heel of photo imaging is: the intensity of light in the imaging environment, whether it is dark field or backlight, it is impossible to keep the center and edge of the image completely consistent. This causes inconsistencies in the brightness of the plates, which seriously interferes with the automatic identification of colony targets. Therefore, if you want to purchase photo imaging, the analysis software must have a background correction function to automatically improve the imaging effect. Scanning imaging is different from creating a uniform surface light source in a light box. The line light source is moved into a surface light source by movement, so the light intensity is very uniform, and its uniformity is usually an order of magnitude higher than the surface light source of the photo light box, from the fundamental of the imaging hardware. The problem of uneven brightness of the colony target is solved, so the counting analysis is very stable. At present, the speed of scanning six 90mm diameter plates at 300dpi resolution (3482×2396 pixel imaging), dark field imaging is about 12 seconds, and backlight imaging is about 20 seconds. In terms of imaging speed, it is photographed with SLR cameras and card machines. The speed is quite. Since the uniformity of light in scanning imaging is much higher than that of photographing, high-quality imaging is achieved in order to achieve "fool" analysis. Another advantage of scanning imaging is that the imaging resolution is adjustable, and the single plate imaging can reach up to 4800 dpi (ie: 25.4/4800=0.00529 mm/pixel), which is far from any photo imaging. It can be expected that scanning imaging will soon become the mainstream choice.

Second, the selection of analysis software

The analysis software is another core component of the fully automated colony counter. Because of the diversity of colony organisms, the performance or visualization on the medium may not be roughly consistent. For such changes, the selection of analysis software should consider: the automatic discharge capacity for various types of imaging interference. For example: whether it can automatically correct the background, and so on. In addition, for the grouped and chain-distributed colonies that are severely stuck together, the level of automatic separation is also a measure of evaluation software. In particular: the intelligent one-click intelligent classification and counting ability of the same type of colonies, as well as the automatic recognition learning ability for colony counting classification, is a key consideration for evaluating analysis software. Now better analysis software, it also integrates the automatic measurement function of the inhibition zone of six 90mm diameter plates, as well as antibiotic titer analysis and drug sensitivity analysis function, which can avoid the user's repeated purchase of imaging hardware. General analysis software should have the ability to save and view analysis results and markup images.

Third, accurate and stable fool operation

The automatic colony counter is to reduce the work intensity of the staff. Under the current high technology, if the estimation is needed to measure the number of colonies, it should be relatively backward. The best is: the analysis software that can accurately and stably operate the "invariant strain", which can automatically adapt to the uncertainty of colony morphology and sample state, so as to avoid constantly adjusting the colony segmentation parameters. Dialogue interactions to erase those contaminated parts.