Optical biosensors have emerged as a powerful tool in analytical biochemistry, offering high sensitivity and specificity in the detection of various biomolecules. This article explores the advancements in the integration of optical biosensors with microfluidic technologies, creating lab-on-a-chip (LOC) platforms that enable rapid, efficient, and miniaturized analysis at the point of need. These LOC platforms leverage optical phenomena such as chemiluminescence and electrochemiluminescence to achieve real-time detection and quantification of analytes, making them ideal for applications in medical diagnostics, environmental monitoring, and food safety. Various optical detectors used for detecting chemiluminescence are reviewed, including single-point detectors such as photomultiplier tubes (PMT) and avalanche photodiodes (APD), and pixelated detectors such as charge-coupled devices (CCD) and complementary metal–oxide–semiconductor (CMOS) sensors. A significant advancement discussed in this review is the integration of optical biosensors with pixelated image sensors, particularly CMOS image sensors. These sensors provide numerous advantages over traditional single-point detectors, including high-resolution imaging, spatially resolved measurements, and the ability to simultaneously detect multiple analytes. Their compact size, low power consumption, and cost-effectiveness further enhance their suitability for portable and point-of-care diagnostic devices. In the future, the integration of machine learning algorithms with these technologies promises to enhance data analysis and interpretation, driving the development of more sophisticated, efficient, and accessible diagnostic tools for diverse applications.

Detection of microbial pathogens is important for food safety reasons, and for monitoring sanitation in laboratory environments and health care settings. Traditional detection methods such as culture-based and nucleic acid-based methods are time-consuming, laborious, and require expensive laboratory equipment. Recently, ATP-based bioluminescence methods were developed to assess surface contamination, with commercial products available. In this study, we introduce a biosensor based on a CMOS image sensor for ATP-mediated chemiluminescence detection. The original lens and IR filter were removed from the CMOS sensor revealing a 12 MP periodic microlens/pixel array on an area of 6.5 mm × 3.6 mm. UltraSnap swabs are used to collect samples from solid surfaces including personal electronic devices, and office and laboratory equipment. Samples mixed with chemiluminescence reagents were placed directly on the surface of the image sensor. Close proximity of the sample to the photodiode array leads to high photon collection efficiency. The population of microorganisms can be assessed and quantified by analyzing the intensity of measured chemiluminescence. We report a linear range and limit of detection for measuring ATP in UltraSnap buffer of 10-1000 nM and 225 fmol, respectively. The performance of the CMOS-based device was compared to a commercial luminometer, and a high correlation with a Pearson's correlation coefficient of 0.98589 was obtained. The Bland-Altman plot showed no significant bias between the results of the two methods. Finally, microbial contamination of different surfaces was analyzed with both methods, and the CMOS biosensor exhibited the same trend as the commercial luminometer.

Electrochemiluminescence (ECL) is a bioanalytical technique with numerous advantages, including the potential for high temporal and spatial resolution, a high signal-to-noise ratio, a broad dynamic range, and rapid measurement capabilities. To reduce the complexity of a multi-electrode approach, we use a single-electrode electrochemiluminescence (SE-ECL) configuration to achieve the simultaneous emission and detection of multiple colors for applications that require multiplexed detection of several analytes. This method exploits intrinsic differences in the electric potential applied along single electrodes built into electrochemical cells, enabling the achievement of distinct colors through selective excitation of ECL luminophores. We present results on the optimization of SE-ECL intensity for different channel lengths and widths, with sum intensities being 5 times larger for 6 cm vs. 2 cm channels and linearly increasing with the width of the channels. Furthermore, we demonstrated for the first time that applying Alternating Current (AC) voltage within the single electrode setup for driving the ECL reactions has a dramatic effect on the emitted light intensity, with square waveforms resulting in higher intensities vs sine waveforms. Additionally, multiplexed multicolor SE-ECL on a 6.5 mm × 3.6 mm CMOS semiconductor image sensor was demonstrated for the first time, with the ability to simultaneously distinguish four different colors, leading to the ability to measure multiple analytes.

Sustainable functionalization of bacterial cellulose for cost‐effective bionanocomposites with desired properties has received growing attention in recent years. This article presents the results of work aimed at obtaining bionanocomposite materials based on bacterial cellulose, a natural and eco‐friendly material. Bacterial cellulose obtained from the Kombucha symbiotic culture of bacteria and yeast (SCOBY) fermentation process is functionalized by embedding with diatom frustules, silver nanoparticles (AgNPs), and poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). The effects of functionalization on mechanical, optical, plasmonic, electrical, chemiluminescent, and antimicrobial properties are evaluated. Morphological characteristics of the nanocomposites are studied using electron microscopy. Addition of diatom frustules introduced into the SCOBY culture media results in bionanocomposite materials with enhanced tensile strength and increased ultraviolet (UV) blockage properties. In situ functionalization of bacterial cellulose with AgNPs tunes plasmonic and chemiluminescent properties, revealing the biosensing potential of the material. Modified bacterial cellulose shows antimicrobial activity in experiments with gram‐positive and gram‐negative bacteria. Dual functionalization of bacterial cellulose with PEDOT:PSS and AgNPs results in improved electrical conductivity of the bionanocomposite. Overall, bottom‐up physical functionalization approaches and the resulting bionanocomposite materials will open up new opportunities for the low‐cost production of green materials and contribute to the development of a sustainable economy.

Rapid and reliable microbial contamination detection is essential for hygiene monitoring in food production, healthcare, and environmental settings. Although ATP-based bioluminescence assays are widely used for rapid cleanliness assessment, conventional luminometer-based systems are limited by high cost, large sample volume requirements, limited dynamic range, and lack of bacterial specificity. In this work, we present an improved CMOS-based bioluminescent biosensing platform for quantitative ATP detection and species-selective detection of Escherichia coli. The platform integrates SuperSnap ATP chemistry and MicroSnap E. coli enzyme-specific assays with a CMOS image sensor housed in a light-tight optical enclosure, enabling chemiluminescence detection using sample volumes as low as 10 μL. Quantitative ATP measurements in SuperSnap buffer exhibited strong linearity and good agreement with a commercial luminometer, achieving a limit of detection of 3.51 nM ATP. When normalized to absolute ATP amount, the CMOS platform demonstrated sensitivity comparable to that of the luminometer despite operating with a 30-fold smaller sample volume. In contrast to the luminometer, which saturated at approximately 75 nM ATP, the CMOS platform maintained linear response up to 200 nM ATP, demonstrating a substantially broader dynamic range without requiring sample dilution. Selective E. coli detection achieved a limit of detection of approximately 412 CFU mL^-1 following 6-h enrichment and 10 min detection, while maintaining selective response in mixed bacterial samples containing Staphylococcus epidermidis. Performance was further validated through representative surface sampling and controlled surface contamination experiments. Overall, the CMOS-based platform provides a low-cost and portable alternative to conventional luminometers for both rapid hygiene monitoring and targeted microbial detection at the point-of-need.

Detection of microbial contamination is essential for hygiene monitoring in food production, healthcare, and environmental settings. While ATP-based bioluminescence assays are widely used for assessing cleanliness, commercial luminometers are costly, require large sample volumes, are non-specific for bacteria, and exhibit low dynamic range that limit their use. We report here a compact biosensing platform for sensitive ATP quantification and species-selective detection of Escherichia coli by integrating SuperSnap ATP chemistry and MicroSnap E. coli enzyme-specific assays. We use a backside-illuminated CMOS image sensor operated in contact-mode, allowing efficient detection of chemiluminescence from sample volumes as low as 10 µL. ATP measurements in SuperSnap buffer exhibit strong linearity and good agreement with commercial luminometers both at low and high concentration ranges, with limits of detection down to 3.51 nM ATP. When normalized to total ATP amount, the CMOS-based platform achieves sensitivity close to the luminometer, despite 30-fold smaller sample volume. Importantly, while the luminometer response saturates at ~75 nM ATP, the CMOS-based system maintains quantification up to 200 nM, demonstrating significantly larger dynamic range, which is a key practical advantage for real-world hygiene monitoring. Species-selective detection of E. coli was demonstrated using MicroSnap chemistry, achieving a detection limit of approximately 412 CFU mL⁻¹ following a 6-hour enrichment and a 10-minute detection step. Selectivity was preserved in mixed bacterial samples containing Staphylococcus epidermidis, confirming enzyme-mediated specificity. These results establish CMOS-based bioluminescent biosensing as a low-cost, portable, and versatile tool for rapid hygiene monitoring and targeted microbial detection at the point-of-need.