A simple and low-cost biofilm quantification method using LED and CMOS image sensor.

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.

[1]  R. Bakke,et al.  Quantification of biofilm accumulation by an optical approach. , 2001, Journal of microbiological methods.

[2]  Se-Hwan Paek,et al.  Lens-free shadow image based high-throughput continuous cell monitoring technique. , 2012, Biosensors & bioelectronics.

[3]  Krzysztof Iniewski,et al.  Lensfree Imaging Cytometry and Diagnostics for Point-of-Care and Telemedicine Applications , 2011 .

[4]  Yongjun Feng,et al.  Indole Affects Biofilm Formation in Bacteria , 2010, Indian Journal of Microbiology.

[5]  Aydogan Ozcan,et al.  Imaging without lenses: achievements and remaining challenges of wide-field on-chip microscopy , 2012, Nature Methods.

[6]  P. Knežević,et al.  A colorimetric microtiter plate method for assessment of phage effect on Pseudomonas aeruginosa biofilm. , 2008, Journal of microbiological methods.

[7]  D. Campoccia,et al.  Detection of biofilm-forming strains of Staphylococcus epidermidis and S. aureus , 2002, Expert review of molecular diagnostics.

[8]  Aydogan Ozcan,et al.  Wide-field optical detection of nanoparticles using on-chip microscopy and self-assembled nanolenses , 2013, Nature Photonics.

[9]  A. Ozcan,et al.  Lensfree holographic imaging of antibody microarrays for high-throughput detection of leukocyte numbers and function. , 2010, Analytical chemistry.

[10]  S. Molin,et al.  The clinical impact of bacterial biofilms , 2011, International Journal of Oral Science.

[11]  A. Stojadinovic,et al.  An overview of biofilm and its detection in clinical samples. , 2012, Journal of wound care.

[12]  Krzysztof Iniewski,et al.  CMOS Biomicrosystems: Where Electronics Meet Biology , 2011 .

[13]  C. Keane,et al.  New method for detecting slime production by coagulase negative staphylococci. , 1989, Journal of clinical pathology.

[14]  Derek K. Tseng,et al.  Lensfree holographic imaging for on-chip cytometry and diagnostics. , 2009, Lab on a chip.

[15]  Aydogan Ozcan,et al.  Multi-color LUCAS: Lensfree On-chip Cytometry Using Tunable Monochromatic Illumination and Digital Noise Reduction , 2008 .

[16]  R. Kolter,et al.  Genetic analysis of Escherichia coli biofilm formation: roles of flagella, motility, chemotaxis and type I pili , 1998, Molecular microbiology.

[17]  Aydogan Ozcan,et al.  High-throughput lens-free blood analysis on a chip. , 2010, Analytical chemistry.

[18]  Hans-Curt Flemming,et al.  The EPS Matrix: The “House of Biofilm Cells” , 2007, Journal of bacteriology.

[19]  Ji-Woon Yang,et al.  LED and CMOS image sensor based hemoglobin concentration measurement technique , 2011 .

[20]  Derek Tseng,et al.  Lensless on-chip imaging of cells provides a new tool for high-throughput cell-biology and medical diagnostics. , 2009, Journal of visualized experiments : JoVE.

[21]  J. Fink-Gremmels,et al.  Staphylococcus epidermidis biofilm quantification: effect of different solvents and dyes. , 2014, Journal of microbiological methods.

[22]  D. Kadouri,et al.  Growing and Analyzing Static Biofilms , 2006, Current protocols in microbiology.

[23]  Aydogan Ozcan,et al.  High‐throughput lensfree imaging and characterization of a heterogeneous cell solution on a chip , 2009, Biotechnology and bioengineering.

[24]  Derek Tseng,et al.  Compact, light-weight and cost-effective microscope based on lensless incoherent holography for telemedicine applications. , 2010, Lab on a chip.