Handheld spectrophotometer with modified filters for rapid microbial contaminant detection

Overview

This technology adapts a proven handheld spectrometer platform (PhotosynQ) into a sensitive, easy-to-use tool for detecting, distinguishing, and quantifying microbial contaminants in liquid samples. Conventional spectrophotometers can identify microbes and measure concentrations by analyzing how different wavelengths of light interact with cells, but they are typically bulky, expensive, and confined to laboratory settings. By leveraging a portable spectrometer already validated for complex multi-wavelength photosynthesis measurements, this solution brings laboratory-grade microbial detection capability directly to the field.

The system is designed for rapid screening of contamination sources and levels, making it valuable for water quality monitoring, food and beverage safety, clinical diagnostics, environmental assessment, and industrial process control. The combination of autofluorescence detection with optional dye-enhanced filter inserts enables both broad screening and targeted identification of specific microbial classes.

Technical specifications

Core platform:

• Adapted handheld spectrometer based on the PhotosynQ platform, originally developed at Michigan State University for tracking photosynthesis
• Multi-wavelength light analysis capable of distinguishing microbial classes based on spectral signatures
• Portable, battery-powered form factor suitable for field deployment

Modified filter system:

• Customized syringe filter inserts (for example, a 50 mL syringe paired with a 0.02-micron filter) concentrate microbial cells from solution samples
• Filter inserts can be loaded with fluorescent dyes that selectively bind to target microbes
• Compatible with off-the-shelf filter hardware (such as Millipore membranes), reducing customization cost

Detection capabilities:

• Autofluorescence-based detection and quantification of microbial contaminants without added reagents
• Dye-enhanced detection for improved sensitivity and specificity, including:
  • MycoLight Green for both gram-positive and gram-negative bacteria
  • MycoLight Red combined with Wheat Germ Agglutinin for specific gram-positive bacteria identification
• Concentration of samples on filters enables extreme sensitivity for low-abundance contaminants

Technology readiness level

The project is at an early-to-mid development stage. The underlying PhotosynQ spectrometer platform is already validated through long-term collaborative use at Michigan State University for complex photosynthetic measurements, providing a strong technical foundation. Future validation will be conducted in collaboration with the David Kramer Lab at MSU, the originator of the PhotosynQ technology. Planned validation activities include testing the handheld spectrophotometer with customized syringe filters against various microbial contaminants, evaluating autofluorescence-based detection performance, and assessing dye-enhanced sensitivity for distinguishing gram-positive and gram-negative bacteria. Successful completion of these validation steps will establish the system's readiness for broader deployment and field testing.