Manufacturing of Microfluidic Devices with Interchangeable Commercial Fiber Optic Sensors

Optical fiber chemical sensing of anionic surfactants using a microfluidic polymer chip with embedded ion-selective fluorescence optode

This study introduces a novel microfluidic polymer chip system that employs an embedded anionic surfactant (AS) ion-selective fluorescence optode (AS fluorescence optode) as a detector for measuring AS. The AS fluorescent optode comprises a lactone form of rhodamine B (L-RB) embedded in 2-nitrophenyl octyl ether plasticized poly (vinyl chloride) membrane. The AS fluorescence optode demonstrated a linear correlation between fluorescence intensity peak heights and AS concentrations within the range of less than 20 µM under optimal flow conditions. The limit of detection for AS was approximately 0.06 µM. The microfluidic system was utilized to measure AS levels in environmental samples, such as river water and tap water.

In-situ multicore fibre-based pH mapping through obstacles in integrated microfluidic devices

Microfluidic systems with integrated sensors are ideal platforms to study and emulate processes such as complex multiphase flow and reactive transport in porous media, numerical modeling of bulk systems in medicine, and in engineering. Existing commercial optical fibre sensing systems used in integrated microfluidic devices are based on single-core fibres, limiting the spatial resolution in parameter measurements in such application scenarios. Here, we propose a multicore fibre-based pH system for in-situ pH mapping with tens of micrometer spatial resolution in microfluidic devices. The demonstration uses custom laser-manufactured glass microfluidic devices (called further micromodels) consisting of two round ports. The micromodels comprise two lintels for the injection of various pH buffers and an outlet. The two-port system facilitates the injection of various pH solutions using independent pressure pumps. The multicore fibre imaging system provides spatial information about the pH environment from the intensity distribution of fluorescence emission from the sensor attached to the fibre end facet, making use of the cores in the fibre as independent measurement channels. As proof-of-concept, we performed pH measurements in micromodels through obstacles (glass and rock beads), showing that the particle features can be clearly distinguishable from the intensity distribution from the fibre sensor.