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Fiber optic sensors based on the vapor deposited conducting polymer

on November 11, 2019

fibre-1562702_640A team of researchers from Australia has developed a mathematical model, which is based on energy deposition and the laser-induced damage threshold (LIDT) for low-intensity light radiation resulting in the appearance of conducting polymers in novel fiber optic sensing applications.

It should be noted that nowadays polymer features are regarded as one of the most potential and studied CP’s, herewith, the material may find numerous applications such as light-emitting diodes (OLED), optical displays, photovoltaic devices, and fiber optic sensors.

The thing is that the poly(3,4-ethylenedioxythiophene) is almost visibly transparent in its doped state, while it converts into an opaque material (dark blue) in the dedoped state, thus, making the polymer ideal for optical applications, for instance, in electrochromic devices and optical fiber sensors.

The interaction between light and the sensing material plays a crucial role in fiber optic sensing. To be more precise, there is a reaction between the sensing material and an external stimulus, therefore, it becomes possible to interrogate and measure the change, linking the optical fiber measurement to the external stimuli. 

Optical fibers are considered to be an ideal example of a way to send light to a volume or point of interest for fiber optic sensing. Usually, “optical material is coated on the side or at the tip of the fiber, which are typically inorganic material”. Numerous recent sensing applications (temperature sensors, hydrogen sensors and polymer functionalization of exposed-core microstructured optical fibers) include fiber tip fabrication and side coating.

Thus, the researchers present a new fiber optic sensing architecture based on coating the tip of an optical fiber with the vapor-deposited conducting polymer. They confirm that such fiber optic sensors enable us to study the unique electrochemical properties of PEDOT:Tos at the sub-micron length scale. Additionally, the polymer material can be integrated with optical waveguides (optical fibers as well) resulting in a range of electro-optical devices.

Optical fibers provide such benefits as immunity to electromagnetic fields, the possibility for in-vivo and distributed measurements with the electrochemical properties of poly((3,4-ethylenedioxythiophene). Also, the researchers prepare a technique to gradually deposit PEDOT:Tos layers with desired thicknesses on the tip of optical fibers to produce such a fiber optic sensor.

Finally, the fiber optic technology was tested, and the polymer material was deposited at the tip of cleaned and cleaved SMF-28 optical fiber. Moreover, the deposition technique is based on 4 steps: “ 1. Oxidant solution preparation, 2. Oxidant coating and splitting at the tip of the fiber, 3. VPP process and 4. Washing of unbound and unreacted monomers”.

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editorFiber optic sensors based on the vapor deposited conducting polymer

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