title: A simple and low-cost biofilm quantification method using LED and  CMOS image sensor.
abstract: A novel biofilm detection platform, which consists of a cost-effective red, green, and blue light-emitting diode (RGB LED) as a light source and a lens-free CMOS image sensor as a detector, is designed. This system can measure the diffraction patterns of cells from their shadow images, and gather light absorbance information according to the concentration of biofilms through a simple image processing procedure. Compared to a bulky and expensive commercial spectrophotometer, this platform can provide accurate and reproducible biofilm concentration detection and is simple, compact, and inexpensive. Biofilms originating from various bacterial strains, including Pseudomonas aeruginosa (P. aeruginosa), were tested to demonstrate the efficacy of this new biofilm detection approach. The results were compared with the results obtained from a commercial spectrophotometer. To utilize a cost-effective light source (i.e., an LED) for biofilm detection, the illumination conditions were optimized. For accurate and reproducible biofilm detection, a simple, custom-coded image processing algorithm was developed and applied to a five-megapixel CMOS image sensor, which is a cost-effective detector. The concentration of biofilms formed by P. aeruginosa was detected and quantified by varying the indole concentration, and the results were compared with the results obtained from a commercial spectrophotometer. The correlation value of the results from those two systems was 0.981 (N = 9, P < 0.01) and the coefficients of variation (CVs) were approximately threefold lower at the CMOS image-sensor platform.
authors.affiliation: Department of Electronics and Information Engineering, Korea University, Sejong 339-700, Republic of Korea.
authors.forename: Yeon Hwa
authors.initials: YH
authors.lastname: Kwak
authors.forename: Junhee
authors.initials: J
authors.lastname: Lee
authors.forename: Junghoon
authors.initials: J
authors.lastname: Lee
authors.forename: Soo Hwan
authors.initials: SH
authors.lastname: Kwak
authors.forename: Sangwoo
authors.initials: S
authors.lastname: Oh
authors.forename: Se-Hwan
authors.initials: SH
authors.lastname: Paek
authors.forename: Un-Hwan
authors.initials: UH
authors.lastname: Ha
authors.forename: Sungkyu
authors.initials: S
authors.lastname: Seo
mesh_terms: D018441:Biofilms; D015374:Biosensing Techniques; D007091:Image Processing, Computer-Assisted; D061848:Optical Imaging / Q000379:methods*; D011550:Pseudomonas aeruginosa