Rapid On-Site Formation of a Free-Standing Flexible Optical Link for Sensing Applications

Abstract

An optical link, based on a conventional Scotch tape waveguide, for sensing applications requiring rapid on-site assembly is proposed and demonstrated. The flexible waveguide contains an integrated aluminum one-dimensional grating coupler that, when stuck on the radiative surface of a light emitting device, allows light to be coupled in and transmitted through the tape, whose tip end is, in turn, adhered onto the photosensitive surface of a photodetector. The (de)coupling approaches exhibit high alignment tolerances that permit the formation of a free-standing flexible optical connection between surface-normal optoelectronic devices without the need of specialized equipment. As the first demonstration of a sensing application, the proposed optical link is easily configured as a cost-effective intensity-based refractometric sensor for liquid detection, which can be applicable to on-site quality and process control of, for example, beverages.

Flexible and Stretchable Photonics: The Next Stretch of Opportunities

“…The interaction of the evanescent tail of a confined waveguide mode or the electric or magnetic field of a metasurface with its environment is useful in chemical detection applications. The analyte may be flowed over the optical device and detected as is, , or binding sites may be used to trap the analyte on the sensor surface. , Chemical sensor flexibility is key not only for wearable or implantable sensors but also to reduce the cost of photonic sensors by fabricating them with traditional R2R processing. Several sensor types have shown good sensitivity in chemical detection on flexible platforms, most notably interferometers and resonators for refractometry sensing and metamaterial surfaces for electromagnetic resonance-based chemical sensing.…”

Pressure Sensitive Adhesive Tape: A Versatile Material Platform for Optical Sensors

“…Inspired by the aforementioned advantages of POFs, Barrios [ 27 ] proposed and demonstrated a plastic free-standing waveguide made of a Scotch tape for liquid refractive index sensing. The flexible waveguide contained an integrated aluminum grating coupler [ 25 , 26 ], which, when stuck on the radiative surface of a light emitting device, allowed light to be coupled in and transmitted through the tape waveguide, whose tip end was, in turn, directly adhered onto the photosensitive surface of a photodetector ( Figure 4 a).…”

“…The development of optical and photonic devices and microsystems has been greatly enhanced by the application of PSA tape to micro- and nanotechnology. For instance, flexible photonic devices have been implemented using PSA tape as an integral functional component, either as a substrate [ 21 , 22 , 23 , 24 ] or as a waveguide [ 25 , 26 , 27 , 28 ]. Tape-supported nanopatterned films have also been successfully transferred to the tip and side surfaces of optical fibers by dissolving or detaching the supporting tape [ 22 ].…”

Flexible Phase Change Materials for Electrically‐Tuned Active Absorbers

“…[ 34 ] Owing to the elastic deformability of flexible substrates, these devices can be mechanically deformed (bent, stretched, twisted, compressed, etc.) and work on curved surfaces, inspiring applications such as flexible optical metasurfaces, [ 35–37 ] wearable photonic healthcare devices, [ 38 ] flexible photodetectors, [ 39 ] chemical and biological sensors, [ 40,41 ] and so on. Moreover, mechanical deformation can also be regarded as an extra degree of freedom for optical metasurfaces.…”

“…The most widely used flexible substrates are polymer materials such as polydimethylsiloxane (PDMS), [ 36 ] polystyrene (PS), [ 37 ] polyimide (PI), [ 38 ] polyethylene terephthalate (PET), [ 39 ] polyethylene glycol (PEG), [ 40 ] and polycarbonate (PC). [ 41 ] However, owing to thermal instability, these flexible polymer substrates can only operate below the temperature of 500 K, [ 44 ] which is contrary to the above‐mentioned high‐temperature requirements of PCMs. Very recently, some specific methods have been developed to fabricate PCMs on flexible substrates, such as inkjet‐printing PCMs on PI substrates, [ 45 ] fabricating PCMs on thin mica sheets, [ 46–52 ] or utilizing extra buffer layers.…”