197 research outputs found
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 a 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.Comment: 12 pages of main draft with 10 figures, 2 pages of supplementary
information with 3 figures. Total 14 page
Bio-inspired all-optical artificial neuromast for 2D flow sensing
We present the design, fabrication and testing of a novel all-optical 2D flow velocity sensor, inspired by a fish lateral line neuromast. This artificial neuromast consists of optical fibres inscribed with Bragg gratings supporting a fluid force recipient sphere. Its dynamic response is modelled based on the Stokes solution for unsteady flow around a sphere and found to agree with experimental results. Tuneable mechanical resonance is predicted, allowing a deconvolution scheme to accurately retrieve fluid flow speed and direction from sensor readings. The optical artificial neuromast achieves a low frequency threshold flow sensing of 5 mm s(-1) and 5 mu m s(-1) at resonance, with a typical linear dynamic range of 38 dB at 100 Hz sampling. Furthermore, the optical artificial neuromast is shown to determine flow direction within a few degrees
Vectorial bending characteristics of long-period grating written in D-shaped fibre
The curvature- or bend-sensing response of long-period gratings (LPG) UV-inscribed in D-shaped fiber has been investigated experimentally. Strong fiber orientation dependence of the spectral response when such LPGs are subjected to dynamic bending has been observed and is shown to form the basis for new vector sensors
Fiber Bragg gratings of type I in SMF-28 and B/Ge fibre and type IIA B/Ge fibre under gamma radiation up to 0.54 MGy
The sensitivities of type I and IIA fibre Bragg gratings written to different reflectivities in SMF-28 and B/Ge fibres to ionizing radiation up to 0.54MGy are investigated. The Bragg wavelength shows a small and rapid increase at the start of irradiation followed by either a plateau (type I) or a decrease (type IIA)
Differential birefringence in Bragg gratings in multicore fiber under transverse stress
We present experimental measurements of the peak splitting of the reflection spectra of fiber Bragg gratings as a result of birefringence induced by transverse loading of a multicore fiber. Measurements show that the splitting is a function of the applied load and the direction of the load relative to the azimuth of the fiber. A model for calculating the stress in the fiber that is due to an applied load is in good agreement with our experimental observations
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