A Polydimethylsiloxane (PDMS) Waveguide Sensor that Mimics a Neuromast to Measure Fluid Flow Velocity

Abstract

Accurate flow measurement is a ubiquitous task in fields such as industry, medical technology, or chemistry; it remains however challenging due to small measurement ranges or erosive flows. Inspiration for possible measurement methods can come from nature, for example from the lateral line organ of fish, which is comprised of hair cells embedded in a gelatinous cupula. When the cupula is deflected by water movement, the hair cells generate neural signals from which the fish gains an accurate representation of its environment. We built a flow sensor mimicking a hair cell, but coupled it with an optical detection method. Light is coupled into a PDMS waveguide that consists of a core and a cladding with a low refractive index contrast to ensure high bending sensitivity. Fluid flow bends the waveguide; this leads to a measurable light loss. The design of our sensory system allows flow measurement in opaque and corrosive fluids while keeping production costs low. To prove the measurement concept, we evaluated the light loss while (a) reproducibly bending the fiber with masses, and (b) exposing the fiber to air flow. The results demonstrate the applicability of an optical fiber as a flow sensor.

Photosensitive Nanodiscs Composed of Human Photoreceptors for Refractive Index Modulation at Selective Wavelengths

“…To apply the variable refractive indices of our photo-NDs, we designed simple waveguide as an optical device with our ND samples and a polydimethylsiloxane (PDMS) structure, which was chosen because of its suitable optical properties, chemical stability for liquid sample, and facile fabrication. − The photosensitive nanodisc based waveguide with flexible structure would be applied to various fields including wearable devices as a novel optical material, whereas the usual optical metamaterials with brittle elements such as silicon, Ag, and Au are hardly employed for a flexible device. Using a mold made by 3D printing, the PDMS formed grooves and a guide pattern (Figure S4).…”

A Soft Material Flow Sensor for Micro Air Vehicles

“…This phenomenon can be expected when is around 100 and might lead to oscillations in the drag coefficient. 39 , 44 We have considered here the average drag coefficient, and further investigations are welcome. However, with an expected Strouhal number close to that of a cylinder, , the affected frequencies, , are above 2000 Hz, which is outside the measuring range of the sensor manufactured.…”

“…Other sensor designs utilize doubly supported sensing elements, such as the spider silk-inspired acoustic sensors developed by Zhou and Miles, 37 the optical fiber described by Stadler et al , 38 , 39 and the recently developed elastic filament velocimetry (EFV) sensor. 40 , 41 The latter relies on drag from the passing flow to elongate a thin, conductive platinum ribbon suspended between two static supports.…”

Flexible flow sensors-enabled intelligent life

“…where n eff is the effective refractive index of the fiber core within the Bragg grating, Λ is the period of its changes. Morphological strategies are utilized to enhance the performance of optical flow sensors, such as soft polymer-based optical waveguide [51,52], weight attachment at distal end of optical fiber [24,53].…”