Automated maintenance-free continuous flow microbial contamination detector

Overview

This solution addresses the challenge of detecting microbial contamination in continuous flow samples where particles move too quickly for conventional spectroscopic identification. The proposed system uses optical tweezers to individually trap and analyze every cell passing through a microfluidic channel, enabling comprehensive detection from an arbitrary volume of relatively clean sample. The platform is designed to hold and analyze every cell in a flow of 1 mL per minute, achieving a detection limit of 0.1 cells per mL within a 10-minute test window. The maintenance-free design supports approximately 1,000 tests per unit, targeting a cost of around €10 per test and a bill-of-materials near €10,000.

Technical specifications

• Optical trapping mechanism: Single-fibre optical tweezers with holding forces of approximately 400 pN/W, sufficient to counter drag forces of around 10 pN experienced by cells in the microfluidic flow
• Spectroscopic analysis: Raman and fluorescence lifetime microscopy integrated to assess cell type and viability
• Microfluidic integration: All optical components integrated into a single microfluidic channel, with fibre-coupled optical systems used initially to de-risk integration
• Flow rate: Designed to process samples at 1 mL per minute
• Detection sensitivity: Target detection limit of 0.1 cells per mL in a 10-minute test
• Cost targets: Bill-of-materials near €10,000 with a per-test cost of approximately €10
• Design lifespan: 1,000 tests of 10 minutes each before maintenance is required

Technology readiness level

This technology is at an early-to-mid stage of development. The concept builds on existing optical tweezer and spectroscopic approaches that have been explored for over a decade in high-value applications such as cancer cell sorting, but miniaturized versions of key components (including lensed fibres) are now commercially available. The research team plans a staged validation approach: first characterizing the most manufacturable optical tweezer configuration, then using benchtop Raman and fluorescence lifetime microscopes to train a model for determining viability and species of microbial contamination, followed by specifying a simplified and lower-cost spectroscopic system, and finally integrating all optics into a single microfluidic platform using fibre-coupled systems to reduce integration risk.