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Advances in photomedicine and optogenetics have defined the problem of efficient light delivery in vivo. Recently, hydrogels have been proposed as alternatives to glass or polymer fibers. These materials provide remarkable versatility, biocompatibility and easy fabrication protocols. Here, we investigate the usability of waveguides from poly(ethylene glycol) dimethacrylate for targeted light delivery and diffusion. Different hydrogel compositions were characterized with regard to water content, chemical stability, elasticity, refractive index and optical losses. Differences in refractive index were introduced to achieve targeted light delivery, and scattering polystyrene particles were dispersed in the hydrogel samples to diffuse the incident light. Complex constructs were produced to demonstrate the versatility of hydrogel waveguides. © 2019 Optical Society of America.

Advances in photomedicine and optogenetics have defined the problem of efficient light delivery in vivo. Recently, hydrogels have been proposed as alternatives to glass or polymer fibers. These materials provide remarkable versatility, biocompatibility and easy fabrication protocols. Here, we investigate the usability of waveguides from poly(ethylene glycol) dimethacrylate for targeted light delivery and diffusion. Different hydrogel compositions were characterized with regard to water content, chemical stability, elasticity, refractive index and optical losses. Differences in refractive index were introduced to achieve targeted light delivery, and scattering polystyrene particles were dispersed in the hydrogel samples to diffuse the incident light. Complex constructs were produced to demonstrate the versatility of hydrogel waveguides. © 2019 Optical Society of America.

Developing ultrasensitive chemical sensors with small scale and fast response through simple design and low-cost fabrication is highly desired but still challenging. Herein, a simple and universal sensing platform based on a hydrogel interferometer with femtomol-level sensitivity in detecting (bio)chemical molecules is demonstrated. A unique local concentrating effect (up to 109 folds) in the hydrogel induced by the strong analyte binding and large amount of ligands, combined with the signal amplification effect by optical interference, endows this platform with an ultrahigh sensitivity, specifically 10-14 m for copper ions and 1.0 × 10-11 mg mL-1 for glycoprotein with 2-4 order-of-magnitude enhancement. The specific chemical reactions between selected ligands and target analytes provide high selectivity in detecting complex fluids. This universal principle with broad chemistry, simple physics, and modular design allows for high performance in detecting wide customer choices of analytes, including metal ions and proteins. The scale of the sensor can be down to micrometer size. The nature of the soft gel makes this platform transparent, flexible, stretchable, and compatible with a variety of substrates, showing high sensing stability and robustness after 200 cycles of bending or stretching. The outstanding sensing performance grants this platform great promise in broad practical applications.

Developing ultrasensitive chemical sensors with small scale and fast response through simple design and low-cost fabrication is highly desired but still challenging. Herein, a simple and universal sensing platform based on a hydrogel interferometer with femtomol-level sensitivity in detecting (bio)chemical molecules is demonstrated. A unique local concentrating effect (up to 109 folds) in the hydrogel induced by the strong analyte binding and large amount of ligands, combined with the signal amplification effect by optical interference, endows this platform with an ultrahigh sensitivity, specifically 10-14 m for copper ions and 1.0 × 10-11 mg mL-1 for glycoprotein with 2-4 order-of-magnitude enhancement. The specific chemical reactions between selected ligands and target analytes provide high selectivity in detecting complex fluids. This universal principle with broad chemistry, simple physics, and modular design allows for high performance in detecting wide customer choices of analytes, including metal ions and proteins. The scale of the sensor can be down to micrometer size. The nature of the soft gel makes this platform transparent, flexible, stretchable, and compatible with a variety of substrates, showing high sensing stability and robustness after 200 cycles of bending or stretching. The outstanding sensing performance grants this platform great promise in broad practical applications.

We report excellent piezoelectric and pyroelectric properties of electrospun nanofibers based on the hybrid ferroelectric 1,4-diazabicyclo[2.2.2] octane perrhenate (dabcoHReO4). Ferroelectric nanoparticles are embedded into the fibers being naturally aligned with the major polarization component along the fiber axis. A flexible piezoelectric nanogenerator consisting of an aligned array of dabcoHReO4 fibers provides a voltage above 100 mV under a moderate strain level. The pyroelectric coefficient in as-electrospun dabcoHReO4 fiber mat is similar to that in poled polyvinylidene difluoride nanofibers. The results show that the nanofibers based on dabcoHReO4 have a great potential for pyroelectric and piezoelectric autonomous energy harvesting with natural advantages such as biocompatibility, flexibility, low cost, and easy fabrication. © 2014 AIP Publishing LLC.

In this Letter, we report a method to prepare a liquid crystal (LC) lens based on a variable pretilt angle of a photoalignment (PA) layer. With precise control of the irradiance, such PA provides good control on the pretilt angle that can be tuned in the range of 1 degrees-89 degrees. Therefore, the precise control of the irradiance generates a spatially varying pretilt angle with any desired pretilt angle profile. Thus, the tunable LC lenses have been fabricated and characterized. With low voltage operations, easy fabrication, and relatively high switching speed, such lenses can be applied in many modern optical and photonic devices. (C) 2013 Optical Society of America