Hollow Core Waveguide Flow Cell for Bioreactor Sensitivity
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Solution Overview
Problem
Current optical spectroscopy flow cells for bioprocess monitoring have low sensitivity, requiring long measurement times or extended excitation beam paths, which is a limitation for portable optical spectroscopy instruments used in bio-pharmaceutical industries.
Innovation Solution
A hollow core waveguide flow cell design with a window at one end and a mirror at the other end to create a long path length for excitation light interaction with the fluid sample, coupled with conduits for fluid flow and an optical spectrometer for analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pathlength of a flow cell is extended to increase signals for optical spectroscopy measurements, then sensitivity is improved, but the device size and complexity increase
Solution Approach 1:
The patent transitions from a conventional linear pathlength extension to a hollow core waveguide structure that confines light through total internal reflection at angled interfaces. This dimensional transformation allows the light to traverse a much longer effective pathlength (up to 500 cm) within a compact cylindrical geometry, thereby achieving high sensitivity without proportionally increasing the external device dimensions.
Solution Approach 2:
The hollow core waveguide structure serves multiple functions simultaneously: it acts as both the optical path confinement structure and the fluid sample holder. The waveguide core accommodates the liquid sample while guiding the excitation light through total internal reflection, eliminating the need for separate long-pathlength flow cell designs and reducing overall system complexity.
2Illumination intensity
If long-pathlength flow cells are used to collect enough sample light, then signal strength is improved, but measurement time increases
Solution Approach 1:
The hollow core waveguide enables continuous light propagation through the liquid sample without interruption. The excitation light enters through one end, traverses the entire length of the waveguide through total internal reflection, and exits through the other end, providing continuous interaction with the sample throughout the entire pathlength. This continuous action maximizes signal collection efficiency and reduces measurement time compared to conventional methods requiring multiple passes or reflections.
3Ease of operation
If conventional flow cell designs are used with portable optical spectroscopy instruments, then device portability is maintained, but sensitivity is insufficient
Solution Approach 1:
The patent embeds the optical path and fluid sample within a nested hollow core waveguide structure. The waveguide core is nested within the outer cladding structure, creating a compact cylindrical assembly that can be integrated with portable spectroscopy instruments. This nested design allows the long effective pathlength to be contained within a small external footprint, maintaining portability while achieving high sensitivity through the confined optical path.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design enhances sensitivity by increasing the interaction length of the excitation light with the fluid sample, enabling high-sensitivity in-line analysis of liquid samples, improving detection limits and reducing measurement times for portable optical spectroscopy.
Implementation Method 1
These flow cells utilize a capillary as the waveguide to confine the light inside the liquid of interest
Implementation Method 2
a mirror at the outlet is optically coupled to the waveguide at the second end
Implementation Method 3
A window at the inlet is optically coupled to the waveguide at the first end
Data Source
AI summary
A flow cell for use with a spectrometer is described. The flow cell includes a waveguide having a hollow core. An inlet is fluidly coupled at a first end of the hollow core, and an outlet is fluidly coupled at a second end of the hollow core. A window at the inlet is optically coupled to the waveguide at the second end, and a mirror at the outlet is optically coupled to the waveguide at the second end. The flow cell also includes a first conduit configured to couple a fluid to the inlet, and a second conduit configured to couple the fluid to the outlet. Methods and systems using the flow cell are described. For example, methods and systems for monitoring a bioreactor.