Session CC06: V: Industrial and Applied Physics II

Coupled line networks for microwave realization of the discrete fractional Fourier transform

The discrete Fourier transform is one of the critical operations in information processing, which is conveniently implemented in free-space optics using bulky optical Fourier lens configurations. In this talk, an on-chip realization of the discrete fractional Fourier transform (DFrFT) is proposed and experimentally implemented in the microwave domain utilizing a passive metamaterial coupled lines network (MCLN). This renders a lensless device capable of performing the DFrFT in real time. In its core, the MCLN comprises N  microstrip transmission lines coupled to their nearest neighbors through an array of interdigital capacitors composed of interlaced microstrip fingers. In the latter, the dimension and number of fingers allow for controlled and enhanced coupling terms that render the required DFrFT couplings highly accurate. The architecture is particularly illustrated by modelling and experimentally realizing a 16×16 MCLN so that its performance can be tested.

 

The proposed innovative approach is versatile and is capable of being used in various applications where DFrFT is an essential tool. The proposed design scheme based on MCLN is scalable across the frequency spectrum and can be applied to the millimeter and submillimeter wave systems.   

Defects and calibration in universal programmable photonic circuits with interlaced DFRFT layers

Universal programmable photonic circuits are photonic platforms which can be controlled to perform arbitrary NxN transformations (usually restricted to U(N) or SU(N)). In recent years, research has been conducted on a promising class of universal structures consisting of alternating phase shift layers and a general transformation. One such important transformation, the Discrete Fourier Transform, can be generalized into what is known as the Discrete Fractional Fourier Transform (DFrFT). Using DRrRT's we have shown that universality can be achieved with N + 1 phase layers [1]. We extend this analysis by showing that universality is not compromised by perturbations of the transformation layers and consider the effect of defects in the phase components [2].   

Reusable Surface Amplified Nanobiosensor for the Detection of Airborne Virus

We reported a reusable surface-amplified nano biosensor for monitoring airborne viruses with a sub-PFU/mL detection limit. In this work, sandwich structures were formed by attaching target virus molecules to antibody-functionalized magnetic particles and alkaline phosphatase (ALP) enzyme. Then, electrochemical markers were generated by ALPs trapped on the Ni patterns by the external magnetic field, resulting in signal amplification. We detected target hemagglutinin (HA) of influenza A (H1N1) virus down to 10 aM concentration using a single sensor chip. Even after repeated sensing measures over the 18 times, the sensor maintained a consistent sensing signal. Moreover, airborne influenza viruses collected from the air could be measured down to sub-PFU/mL level. Considering the reusability and ultrasensitivity of our sensors, it could be a powerful tool for the monitoring of airborne pathogens and help to prevent epidemics by airborne pathogens.

  

Reusable Biosensing Platforms Based on Magnetically-refreshable Receptor Structures

We report a magnetically-refreshable receptor platform (MRP) structure which can be integrated with versatile nanodevice-based sensors to build reusable biosensors using virtually-general receptor molecules. This structure allows one to trap or detrap receptors on nano-biosensor surfaces for repeated sensing operations. As a proof of concepts, we demonstrated the repeated sensing measurements of fluorescence biosensors and field-effect transistor (FET)-based biosensors. Significantly, our method enables the assembly of single-layered structures of receptor-functionalized nanobeads on the transducer surface, so that an active antibody can be placed within a Debye length from the sensor surface. Furthermore, we also showed that a single sensor chip could be utilized to detect two different target molecules simply by replacing receptor molecules. Since our method enables multiple biosensing operations by applying external magnetic fields without any harsh chemical treatment, it can be utilized for virtually-general receptor molecular species and versatile biosensor structures.   

How aerogel substrates affect the biomechanical and biochemical properties of collagen I: An in vitro study

Collagen, the most abundant protein in mammals, is often used as a layer between biomaterials and cells/tissues to enhance cell attachment. Without proper cell attachment, key cellular functions such as proliferation will not occur, therefore the collagen layer plays an important role in tissue construction. Our earlier studies demonstrated that rat tail collagen I provided optimum cell attachment conditions for PC12 cells on aerogels at a concentration of 4µg/cm² and was the preferred dilution ratio for aerogels with pore diameters from 50nm to 10um. A strong dependency of the collagen microstructure on the substrate topography was however observed and thus demanded further investigation. Here, the authors present a comprehensive analysis of how the collagen microstructure is affected by its concentration, as a function of key aerogel substrate properties. These include surface roughness, Young’s modulus, and pore diameter. Concentrations that were tested ranged from X1(4µg/ cm²) to X5(20µg/cm²) and results indicate a gradual transformation from a fibrous layer to a continuous thin film where the individual collagen fibers are no longer distinguishable. Results suggest that the onset of this transformation is mostly dictated by the aerogel surface roughness. Furthermore, the tension in individual collagen fibers, which was affected by the substrate pore diameter, determined the formation of a collagen film and as a result played a key role in the continuity or discontinuity of the collagen film.   

Bioelectrical Nose Using Odorant-Binding Protein as a Molecular Transporter Mimicking Human Olfactory System for Direct Gas Sensing

We report a portable bioelectronic nose using odorant-binding protein (OBP) as a molecular transporter for the direct detection of odorant gas molecules. In this study, a 3D-printed case with a gas-permeable membrane on one side was filled with an OBP solution, and an olfactory receptor-functionalized carbon nanotube FET (CNT-FET) was inserted to the case. Here, OBP molecules in the solution were utilized as a vehicle to transport odorant gases to olfactory receptor on a CNT-FET device, mimicking human olfactory system. Our bioelectronic nose platform based on I7 receptor dose-dependently responded to octanal gas in real time and the sensitivity improved by ~100% compared with those without OBP. Furthermore, it also be used to detect odorant gas molecules from orange juice scent, and the bioelectronic nose with OBP showed a higher sensitivity than those without it. Since our bioelectronic nose platform allows us to directly detect gas-phase odorant molecules including a rather insoluble species, it could be a powerful tool for versatile applications and basic research based on a bioelectronic nose.   

Emerging second-order nonlinearity in two-dimensional material functionalized silica microcavities

One fundamental challenge for nonlinear optics is the simultaneous use of second- and third-order nonlinear processes since the nonlinear susceptibility is generally intrinsic to the material. An essential requirement for second-order nonlinear processes to occur is inversion symmetry breaking, but state-of-the-art ultrahigh-Q devices are made of centrosymmetric crystals and amorphous materials such as silica and silicon, and only third-order processes can be utilized in these platforms. We herein demonstrate a second-order nonlinear photonic platform by functionalizing ultrahigh-Q silica microspheres with few-layer tungsten diselenide (WSe₂) two-dimensional material. The presence of the manolayer flake drastically changes the nonlinear susceptibilities of the silica microcavity, leading to cavity-enhanced second-harmonic (SH) generation and sum-frequency generation by continuous-wave (CW) excitation at a power level of only a few hundred microwatts. This result relies on the giant second-order nonlinearity of the monolayer WSe₂ [1,2]. The layer number dependence of SH light confirms that the second-order nonlinearity originates from the integrated WSe₂, not from intrinsic surface symmetry breaking of the cavity material [3]. We reveal the mechanism of the dynamic phase-matching process, which governs the conversion efficiency of SH light by measuring the pump power dependence. We also demonstrate the coexistence of second- and third-order nonlinearities and its flexible control in a single device, unlocking the fundamental limitation of optical nonlinearities intrinsic to the cavity material.

[1] Y. Li, et al., Nano Lett. 13, 3329 (2013).

[2] N. Kumar, et al., Phys. Rev. B 87, 161403 (2013).

[3] X. Zhang, et al., Nat. Photon. 13, 21 445 (2019).   

Thermally-limited cancellation-free microwave impedance microscopy with monolithic silicon cantilever probes

Microwave impedance microscopy (MIM) is an emerging scanning probe technique for nanoscale complex permittivity mapping. To date, the two most significant hurdles that limit its widespread use are the requirements of high-precision cancellation circuits and specialized microwave probes. In this talk, I will show that neither is required for high-performance MIM. We demonstrate thermal-noise-limited, drift- and background-free MIM operation with minimal topography crosstalk and unprecedented sensitivity of ~zF, using silicon cantilever probes, without cancellation. Our approach makes MIM drastically more accessible and paves the way for more advanced modes and its integration with other techniques requiring high-performance silicon-based probes.   

Revolutionizing Biologically-inspired AI Hardware Accelerators: Unveiling the Potential of Metal Self-Directed Channel (M-SDC) Memristors in Neuromorphic Computing

Moore's Law, guiding transistor scaling for five decades, faces challenges with Dennard's scaling law weakening since 2004. Escalating lithography costs hinder further transistor node reduction, impacting performance gains. AI-driven demand strains data centers' energy consumption, questioning future computing sustainability. Researchers explore alternatives, including dark silicon, 3D stacking, superconducting structures, spintronics, and carbon nanotubes. Neuromorphic computing, designed to overcome the von Neumann bottleneck, adopts bio-inspired architecture. Memristors, the fourth electronic component, offer potential despite challenges. Metal Self-Directed Channel (M-SDC) Memristors, gaining prominence, undergo extensive research. Our study delves into M-SDC Memristors, revealing diverse conductance states and enhanced programmability crucial for large-scale neural networks. Our research illuminates M-SDC Memristors' reliability in in-memory architectures, providing insights for sustainable computing advancements. Neuromorphic computing, especially with Memristors, emerges as a promising solution, contributing essential knowledge for navigating challenges and advancing biologically-inspired AI hardware accelerators.   

A Computational Study of Electrostatically-Doped Silicene and Graphene Nanoribbon FETs

This study investigates nanoribbon width variations in Electrically Doped Silicon Nanoribbon Field-Effect Transistors (ED SiNR-FET) and Graphene Nanoribbon Field-Effect Transistors (GNR-FET) to optimize transistor channel width for enhanced performance. Results demonstrate the ED SiNR-FET's superior resilience to impurities, establishing it as the top performer. The systematic evaluation identifies the most conducive nanoribbon width for heightened device performance. The introduction of the extended channel ED-device (ECED) reveals a significantly improved I_ON/I_OFF ratio compared to GNR-FET across various channel lengths. A detailed analysis of a 15 nm ECED SiNR-FET and an 8 nm channel GNR-FET under diverse conditions highlights the ECED's potential for both low-power (LP) and high-performance (HP) applications. The ECED SiNR-FET exhibits a minimal subthreshold swing of 64 mV/dec and a peak transconductance of 63 µS, making it suitable for LP and HP applications, respectively. This research demonstrates ED SiNR-FET's superiority over GNR-FET and underscores the potential of ECED SiNR-FET, presenting better I_ON/I_OFF ratio, subthreshold swing, and transconductance characteristics. This research introduces an innovative transistor design for future CMOS technology.