Graphene, a two-dimensional hexagonal honeycomb carbon structure, is widely used in membrane technologies thanks to its unique optical, electrical, mechanical, thermal, chemical and photoelectric properties. The light weight, mechanical strength, anti-bacterial effect, and pollution-adsorption properties of graphene membranes are valuable in water treatment studies. Incorporation of nanoparticles like carbon nanotubes (CNTs) and metal oxide into the graphene filtering nanocomposite membrane structure can provide an improved photocatalysis process in a water treatment system. With the rapid development of graphene nanocomposites and graphene nanocomposite membrane-based acoustically supported filtering systems, including CNTs and visible-light active metal oxide photocatalyst, it is necessary to develop the researches of sustainable and environmentally friendly applications that can lead to new and groundbreaking water treatment systems. In this review, characteristic properties of graphene and graphene nanocomposites are examined, various methods for the synthesis and dispersion processes of graphene, CNTs, metal oxide and polymer nanocomposites and membrane fabrication and characterization techniques are discussed in details with using literature reports and our laboratory experimental results. Recent membrane developments in water treatment applications and graphene-based membranes are reviewed, and the current challenges and future prospects of membrane technology are discussed.

A solution-processed organic ultraviolet photodetector (UV-PD) is introduced. The active layer of the UV-PD consists of poly(9,9-dioctyl fluorenyl-2,7yleneethynylene) (PFE) and N,N-bis-n-butyl-1,4,5,8- naphthalenediimide (BNDI) with a weight ratio of 3:1 in chloroform. The effect of thermal annealing on the device properties was investigated from room temperature to 80∘C. The full device structure of ITO/PEDOT:PSS/PFE:BNDI (3:1)/Al gave responsivity of 410mA/W at 4V under 1mW/cm2 UV light at 368nm when 60∘C of annealing temperature was used during its preparation. The devices that were annealed over the crystallization temperature of PFE showed a charge transfer resistance increase and a mobility decrease.

Biological particle tracking systems monitor cellular processes or particle behaviors with great accuracy. The emissions of fluorescent molecules or direct images of particles are captured with cameras or photodetectors. The current imaging systems have challenges in detection, collection and analysis of imaging data, penetration depth and complicated set-ups. In this article, a signaling based nanoscale acousto-optic radar and microfluidic multiple particle tracking (MPT) system is proposed based on the theoretical design providing nanoscale optical modulator with vibrating Förster resonance energy transfer (VFRET) and vibrating Cadmium Selenide/Zinc Sulfide (CdSe/ZnS) quantum dots (QDs) on graphene resonators. The modulator combines significant advantages of graphene membranes having wideband resonance frequencies with QDs having broad absorption spectrum and tunable properties. The solution denoted by chirp spread spectrum (CSS) Tag (CSSTag) utilizes classical radar target tracking approaches in nanoscale environments based on the capability to generate CSS sequences identifying different bio-particles. Monte-Carlo simulations show significant performance for MPT with a modulator of 10 μm × 10 μm × 10 μm dimension and several picograms of weight, signal to noise ratio in the range -7 dB to 10 dB, simple light emitting diode sources with power less than 4 W/cm2 and high speed tracking for microfluidic environments.

Spatial modulation (SM) improves spectral efficiency (SE) by creating constellation of active optical antenna indices. However, quantum properties of light are not exploited to improve SE. In this article, multi-plane diffraction (MPD) set-up creating exponentially increasing number of propagation paths for classical sources is exploited to introduce quantum spatial modulation (QSM). Exponential number of paths and quantum superposition based classical symbol generation for transmitting simultaneous multiple classical symbols are both exploited for linear and exponential quantum boosting of SM, respectively. It is theoretically modeled, numerically analyzed and the challenges of joint design of source-channel coding and QSM are discussed.

Graphene resonators are future promising in terms of ultra-low weight, high Young's modulus, strength and wideband resonance frequencies. Besides that, nanoscale optical wireless channels including visible light spectrum are alternatives to radio-frequency communications promising energy efficiency and high data rates. In this article, vibrating multi-layer graphene nanoelectromechanical resonators are combined with designed vibrating Forster resonance energy transfer (VFRET) mechanism to achieve a nanoscale acousto-optic modulator converting vibrations to multi-color photon emissions. The frequency, color and the vibration sensitivity of emission are tunable while vibrations are realized either passively or actively by exploiting acoustic, thermo-acoustic or opto-acoustic properties of graphene. The light is generated by FRET mechanism with oscillating donor-acceptor distance where donor molecules attached on graphene are chosen as CdSe/ZnS core-shell QDs with significant properties of broad absorption spectrum, large cross-sections, tunable emission spectra, size dependent emission wavelength, high photochemical stability and improved quantum yield. The designed modulator achieves acoustic and ultrasound frequencies between several KHz and tens of MHz and radiation power reaching several nanowatts with resonator sizes of hundreds of micrometers for ambient light intensity of 0.1 W/m²/nm. The proposed system promises significant applications including nanoscale acousto-optic communication, transduction, sensing, energy harvesting and biomedical nanoscale communications.