Person: GÜLBAHAR, Burhan Cahit
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Burhan Cahit
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GÜLBAHAR
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Conference paperPublication Open Access MIComp: 3D on-chip magneto-inductive computing with simultaneous wireless information and power transfer(Association for Computing Machinery, Inc, 2018-05-08) Gülbahar, Burhan; Memişoğlu, G.; Electrical & Electronics Engineering; GÜLBAHAR, Burhan CahitOn-chip computing platforms have bottlenecks including cost and physical limits of scaling transistors, communication bottleneck, energy efficiency and speed costs for memory. Three dimensional (3D) design, carbon nanotube materials, memristor based neuromorphic computing, and optical, RF and magneto-inductive (MI) wireless communication solutions are recently proposed. MI channels are non-radiative and non-interfering by forming coupled networks. They are future promising with capabilities of THz frequency, Tbit/s data rate, hundreds of zJ/bit and 109 W/mm2 communication and power transfer (PT) efficiencies, respectively. In addition, recently introduced network topology modulation (NTM) for MI channels provides network communication with low complexity, low latency and simultaneous wireless information and power transfer (SWIPT). In this article, unique advantages of THz MI channels, NTM design, nanoscale materials including graphene and single molecular magnets (SMMs), and 3D design are combined in a novel on-chip computing architecture denoted by MIComp by introducing fully efficient SWIPT for computing purposes. The system is theoretically modeled while the state space of the system obtained with nanoscale size coils and SMMs achieves 1010 to 1016 bits in each cycle and per mm3 volume of chip compared with the current transistor counts of on the orders of 109 per mm2. Furthermore, each MIComp cycle has ability to perform for multiple purposes consisting of computing operations, memory state implementations and on-chip communications. It promises a novel solution for communication, energy and space bottlenecks for on-chip computing design.
Conference paperPublication Metadata only Nanoscale optical communications modulator and acousto-optic transduction with vibrating graphene and resonance energy transfer(IEEE, 2017) Gülbahar, Burhan; Memisoglu, G.; Electrical & Electronics Engineering; GÜLBAHAR, Burhan CahitGraphene 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.Conference paperPublication Metadata only Experimental analysis of RF based multi-plane-diffraction with over-the-air active cellular signal measurements(IEEE, 2020-10-05) Aytekin, A.; Gülbahar, Burhan; Electrical & Electronics Engineering; GÜLBAHAR, Burhan CahitWi-Fi signal interference based radar structures and high spatial efficiency modulator designs utilizing the quantum properties of light with multi-plane-diffraction (MPD) design have been recently introduced. In this study, experimental studies were performed in a full anechoic chamber for wireless RF active cellular channels, inspired by the advantages of the MPD systems. Differences between free space propagation, single-plane and MP diffraction architectures are observed with experimental studies for different diffraction geometries by analyzing interference patterns. The results obtained in this study will form the basis for next generation sensor designs utilizing direct cellular signal interference and RF modulators exploiting the high spatial efficiency of MPD.ArticlePublication Metadata only CSSTag: optical nanoscale radar and particle tracking for in-body and microfluidic systems with vibrating graphene and resonance energy transfer(IEEE, 2017-12) Gülbahar, Burhan; Memisoglu, G.; Electrical & Electronics Engineering; GÜLBAHAR, Burhan CahitBiological particle tracking systems monitor cellular processes or particle behaviors with the 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 paper, 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 and vibrating cadmium selenide/zinc sulfide 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 utilizes classical radar target tracking approaches in nanoscale environments based on the capabilityto 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, the signal-to-noise ratio in the range from -7 to 10 dB, simple light emitting diode sources with power less than 4 W/cm2 and high speed tracking for microfluidic environments.ArticlePublication Open Access Theoretical modeling of viscosity monitoring with vibrating resonance energy transfer for point-of-care and environmental monitoring applications(MDPI, 2019-01-01) Memişoğlu, G.; Gülbahar, Burhan; Zubia, J.; Villatoro, J.; Electrical & Electronics Engineering; GÜLBAHAR, Burhan CahitForster resonance energy transfer (FRET) between two molecules in nanoscale distances is utilized in significant number of applications including biological and chemical applications, monitoring cellular activities, sensors, wireless communications and recently in nanoscale microfluidic radar design denoted by the vibrating FRET (VFRET) exploiting hybrid resonating graphene membrane and FRET design. In this article, a low hardware complexity and novel microfluidic viscosity monitoring system architecture is presented by exploiting VFRET in a novel microfluidic system design. The donor molecules in a microfluidic channel are acoustically vibrated resulting in VFRET in the case of nearby acceptor molecules detected with their periodic optical emission signals. VFRET does not require complicated hardware by directly utilizing molecular interactions detected with the conventional photodetectors. The proposed viscosity measurement system design is theoretically modeled and numerically simulated while the experimental challenges are discussed. It promises point-of-care and environmental monitoring applications including viscosity characterization of blood or polluted water.ArticlePublication Metadata only Energy harvesting and magneto-inductive communications with molecular magnets on vibrating graphene and biomedical applications in the kilohertz to terahertz band(IEEE, 2017-09) Gülbahar, Burhan; Electrical & Electronics Engineering; GÜLBAHAR, Burhan CahitMagneto-inductive (MI) Terahertz (THz) wireless channels provide significant theoretical performances for MI communications (MIC) and wireless power transmission (WPT) in nanoscale networks. Energy harvesting (EH) and signal generation are critical for autonomous operation in challenging mediums including biomedical channels. State of the art electromagnetic vibrational devices have millimeter dimensions while targeting low frequency EH without any real-time communications. In this paper, graphene resonators are combined with single molecule magnets (SMMs) to realize nanoscale EH, MIC, and WPT with novel modulation methods achieving simultaneous wireless information and PT. The unique advantages of graphene including atomic thickness, ultra-low weight, high strain, and resonance frequencies in the Kilohertz to THz band are combined with high and stable magnetic moments of Terbium (III) bis (phthalocyanine) SMMs. Numerical analyses provide tens of nanowatts powers and efficiencies of 10 4W/m3 in acoustic and ultrasound frequencies comparable with vibrational EH devices while millimeter wave carrier generation is numerically analyzed. Proposed model and communication theoretical analysis present a practical framework for challenging applications in the near future by promising simple mechanical design. Applications include nanoscale biomedical tagging including human cells, sensing and communication for diagnosis and treatment, EH and modulation for autonomous nano-robotics, and magnetic particle imaging.ArticlePublication Open Access 3D neuromorphic wireless power transfer and energy transmission based synaptic plasticity(IEEE, 2019) Gülbahar, Burhan; Electrical & Electronics Engineering; GÜLBAHAR, Burhan CahitEnergy consumption combined with scalability and 3D architecture is a fundamental constraint for brain-inspired computing. Neuromorphic architectures including memristive, spintronic, and floating gate metal-oxide-semiconductors achieve energy efficiency while having challenges of 3D design and integration, wiring and energy consumption problems for architectures with massive numbers of neurons and synapses. There are bottlenecks due to the integration of communication, memory, and computation tasks while keeping ultra-low energy consumption. In this paper, wireless power transmission (WPT)-based neuromorphic design and theoretical modeling are proposed to solve bottlenecks and challenges. Neuron functionalities with nonlinear activation functions and spiking, synaptic channels, and plasticity rules are designed with magneto-inductive WPT systems. Tasks of communication, computation, memory, and WPT are combined as an all-in-one solution. Numerical analysis is provided for microscale graphene coils in sub-terahertz frequencies with unique neuron design of coils on 2D circular and 3D Goldberg polyhedron substrates as a proof-of-concept satisfying nonlinear activation mechanisms and synaptic weight adaptation. Layered neuromorphic WPT network is utilized to theoretically model and numerically simulate pattern recognition solutions as a simple application of the proposed system design. Finally, open issues and challenges for realizing WPT-based neuromorphic system design are presented including experimental implementations.ArticlePublication Metadata only A communication theoretical analysis of multiple-access channel capacity in magneto-inductive wireless networks(IEEE, 2017-06) Gülbahar, Burhan; Electrical & Electronics Engineering; GÜLBAHAR, Burhan CahitMagneto-inductive (MI) wireless communications is an emerging subject with a rich set of applications, including local area networks for the Internet-of-Things, wireless body area networks, in-body and on-chip communications, and underwater and underground sensor networks as a low-cost alternative to radio frequency, acoustic or optical methods. Practical MI networks include multiple access channel (MAC) mechanisms for connecting a random number of coils without any specific topology or coil orientation assumptions covering both short and long ranges. However, there is not any information theoretical modeling of MI MAC (MIMAC) capacity of such universal networks with fully coupled frequency selective channel models and exact 3-D coupling model of circular coils instead of long range dipole approximations. In this paper, K-user MIMAC capacity is information theoretically modeled and analyzed, and two-user MIMACs are modeled with explicitly detailed channel responses, bandwidths and coupled thermal noise. K-user MIMAC capacity is achieved through Lagrangian solution with K-user water-filling optimization. Optimum orientations maximizing capacity and received power are theoretically analyzed, and numerically simulated for two-user MIMACs. Constructive gain and destructive interference mechanisms on MIMACs are introduced in comparison with the classical interference based approaches. The theoretical basis promises the utilization of MIMACs in 5G architectures.ArticlePublication Open Access Theory of quantum path computing with Fourier optics and future applications for quantum supremacy, neural networks and nonlinear Schrödinger equations(Nature Research, 2020-07-03) Gülbahar, Burhan; Electrical & Electronics Engineering; GÜLBAHAR, Burhan CahitThe scalability, error correction and practical problem solving are important challenges for quantum computing (QC) as more emphasized by quantum supremacy (QS) experiments. Quantum path computing (QPC), recently introduced for linear optic based QCs as an unconventional design, targets to obtain scalability and practical problem solving. It samples the intensity from the interference of exponentially increasing number of propagation paths obtained in multi-plane diffraction (MPD) of classical particle sources. QPC exploits MPD based quantum temporal correlations of the paths and freely entangled projections at different time instants, for the first time, with the classical light source and intensity measurement while not requiring photon interactions or single photon sources and receivers. In this article, photonic QPC is defined, theoretically modeled and numerically analyzed for arbitrary Fourier optical or quadratic phase set-ups while utilizing both Gaussian and Hermite-Gaussian source laser modes. Problem solving capabilities already including partial sum of Riemann theta functions are extended. Important future applications, implementation challenges and open issues such as universal computation and quantum circuit implementations determining the scope of QC capabilities are discussed. The applications include QS experiments reaching more than 2(100) Feynman paths, quantum neuron implementations and solutions of nonlinear Schrodinger equation.ArticlePublication Open Access Preparation and characterization of freely-suspended graphene nanomechanical membrane devices with quantum dots for point-of-care applications(MDPI, 2020-01-01) Memisoglu, G.; Gülbahar, Burhan; Fernandez Bello, R.; Electrical & Electronics Engineering; GÜLBAHAR, Burhan CahitWe demonstrate freely suspended graphene-based nanomechanical membranes (NMMs) as acoustic sensors in the audible frequency range. Simple and low-cost procedures are used to fabricate NMMs with various thicknesses based on graphene layers grown by graphite exfoliation and solution processed graphene oxide. In addition, NMMs are grafted with quantum dots (QDs) for characterizing mass sensitive vibrational properties. Thickness, roughness, deformation, deflection and emissions of NMMs with attached QDs are experimented and analyzed by utilizing atomic force microscopy, Raman spectroscopy, laser induced deflection analyzer and spectrophotometers. Forster resonance energy transfer (FRET) is experimentally achieved between the QDs attached on NMMs and nearby glass surfaces for illustrating acousto-optic utilization in future experimental implementations combining vibrational properties of NMMs with optical emission properties of QDs. This property denoted as vibrating FRET (VFRET) is previously introduced in theoretical studies while important experimental steps are for the first time achieved in this study for future VFRET implementations. The proposed modeling and experimental methodology are promising for future novel applications such as NMM based biosensing, photonics and VFRET based point-of-care (PoC) devices.