Nanophotonics or nano-optics is the study of the behavior of light on the nanometer scale, and of the interaction of nanometer-scale objects with light. It is a branch of optics, optical engineering, electrical engineering, and nanotechnology. It often (but not exclusively) involves metallic components, which can transport and focus light via surface plasmon
Optical technologies are essential for the rapid and efficient delivery of health care to patients. Efforts have begun to implement these technologies in miniature devices that are implantable in patients for continuous or chronic uses. In this review, we discuss guidelines for biomaterials suitable for use in vivo. Basic optical functions such as focusing, reflection, and diffraction have been realized with biopolymers. Biocompatible optical fibers can deliver sensing or therapeutic-inducing light into tissues and enable optical communications with implanted photonic devices. Wirelessly powered, light-emitting diodes (LEDs) and miniature lasers made of biocompatible materials may offer new approaches in optical sensing and therapy. Advances in biotechnologies, such as optogenetics, enable more sophisticated photonic devices with a high level of integration with neurological or physiological circuits. With further innovations and translational development, implantable photonic devices offer a pathway to improve health monitoring, diagnostics, and light-activated therapies.
Each year, more than 30 million of various medical devices are implanted in the human body, extending and improving the quality of lives of the patients. Among the most implanted are intraocular lens (IOL), stents, artificial joints, cardiac pacemakers, and artificial cochlea. In 2014, more than 20 million IOL procedures were performed worldwide, replacing the natural crystalline lens in the eye in cataract surgery. The development of IOLs was pioneered by Harold Ridley, who as a surgeon in World War II, noticed that poly(methyl methacrylate) (PMMA) fragments from shattered aircraft canopies that penetrated the eyes of pilots remained biologically inert. PMMA remained the dominant material for IOLs for at least 40 years, until the advent of acrylics and silicone. The design and materials are chosen based on the lens power as required on a patient-specific basis. Commercial IOLs offer a fixed refractive power, but future IOLs may incorporate active elements for adaptive accommodation.
The artificial retina, or retinal prosthesis, is an optoelectronic device that is implanted in the eye to restore vision for people suffering from incurable blindness because of retinal degeneration, such as age-related macular degeneration and retinitis pigmentosa. While the photoreceptor cells for these patients are nonfunctional, many of the inner retinal neurons remain functional and can be electrically stimulated to elicit visual responses. A number of retinal prostheses have been approved for human use. One such device, the Alpha IMS subretinal implant, uses multiphotodiode arrays and electrodes that sense light and stimulate the biopolar cells of the inner retina. A power supply is needed for this device because ambient light does not generate sufficient photocurrent to stimulate neurons. Recently, a significant improvement over this design has been demonstrated in rats, in which silicon photodiodes are simultaneously powered and activated by pulsed near-infrared (NIR) illumination delivered by video goggles, obviating the need for an additional power supply.
Beyond these ophthalmic applications, photonic and related technologies for other medical applications have been developed. To fulfill the promise of real-time diagnostics and sensing, as well as chronic light delivery to deep tissues, photonic devices are increasingly designed with biocompatible and implantable properties. Devices made from biocompatible materials can be left in the body for prolonged periods of time and used for long-term health monitoring and therapeutics. Direct integration of photonic components into living tissue can enhance light–tissue interactions, enabling new applications in sensing and light generation. Many existing passive (light guiding, refraction, diffraction, etc.) and active (light generation and detection) optical device functions can be realized by using biocompatible materials.
Here, we overview recent developments in implantable photonic devices. First, we review the requirements and challenges associated with biocompatibility when devices are implanted in the human body. Next, we describe progress toward biocompatible photonic devices, including passive devices and light sources. Passive devices include waveguides, lenses, diffractive and holographic components, reflectors, photonic crystals, and plasmonic devices. Active devices are light sources, which include incoherent light-emitting diodes (LEDs) or coherent lasers. We also describe photonic devices that use these functional elements. Fluorescent probes, single plasmonic nanoparticles, and light-activated drugs are reviewed elsewhere.
Aims and Scope
Nanophotonics covers recent international research results, specific developments in the field and novel applications. It belongs to the top journals in the field. Nanophotonics focuses on the interaction of photons with nano-structures, such as carbon nano-tubes, nano metal particles, nano crystals, semiconductor nano dots, photonic crystals, tissue and DNA. The journal covers the latest developments for physicists, engineers and material scientists, working in fields related to:
Plasmonics: metallic nanostructures and their optical properties
Meta materials, fundamentals and applications
Nanophotonic concepts and devices for solar energy harvesting and conversion
Near-field optical microscopy
Nanowaveguides and devices
Nano Lasers
Nanostructures, nanoparticles, nanotubes, nanowires, nanofibers
Photonic crystals
Integrated silicon photonics
Semiconductor quantum dots
Quantum optics & Quantum information
Ultrafast and nonlinear pulse propagation in nano materials and structures
Light-matter interaction, optical manipulation techniques
Nano-biophotonics
Optofluidics
Optomechanics
System applications based on nanophotonic devices
Nanofabrication techniques, thin film processing, self-assembly
