Orthogonal Probes Research Articles

Simultaneous excitations of odd and even order resonances in plasmonic metasurfaces for an orthogonal terahertz probe.

Most of the compelling phenomena pertaining to plasmonic metamaterials revolve around the associated odd and even order resonances. However, excitation of odd and even order modes is polarization sensitive, particularly in the case of well-accepted split-ring resonator based terahertz (THz) plasmonic metasurfaces. Such a drawback limits the practical applications of plasmonic metasurfaces across the electromagnetic spectrum. In this context, we experimentally demonstrate multi-split-ring resonator based THz metasurfaces capable of simultaneously sustaining odd and even order resonances when the polarization of the probe beam is altered through 90°. We believe this work should be beneficial in realizing polarization-independent switches and frequency selective surfaces.

Three-Dimensional Kelvin Probe Force Microscopy.

Traditional Kelvin probe force microscopy (KPFM) is mainly limited to the characterization of two-dimensional (2D) surfaces, and in situ surface potential (SP) imaging along 3D device surfaces remains a challenge. This paper presents a multimode 3D-KPFM based on an orthogonal cantilever probe (OCP) that can achieve SP mapping of 3D micronano structures. It integrates three working modes: a bending mode for 2D horizontal surface imaging, a torsion mode for vertical sidewall imaging, and a vector tracking-based 3D scanning mode. The customized OCP has a nanoscale tip protruding from the side and underside of the cantilever, rather than the front, and the extended tip makes the proposed approach universally applicable for 3D detection from the nanometer to micrometer scale. The spatial resolution of the proposed method is analyzed by simulation, which shows it can reduce the cantilever homogenization effect. Linearity and energy resolution measurements show that the proposed method has comparable performance to traditional methods. A comparative experiment using a gold-silicon interface verifies the accuracy of the reported method in its bending and torsion modes. Further, the imaging ability of the 3D scanning mode is confirmed in the 3D characterization of a step grating. This technique is applied to the in situ characterization of a microforce sensor with microcomb structures. The experiment results show that this method can excellently achieve the 3D quantitative characterization of topography and SP, including critical dimensions and SP along a 3D device surface. This novel 3D-KPFM technique has many potential applications in the further exploration of 3D micronano devices.

Dual-Polarized, Dual-Band, and Aperture-Shared Synthesis Method for Phased Array Applications

A dual-band and dual-polarized shared-aperture synthesis method for phased array applications is proposed. Dual-polarized slot-coupled microstrip patch elements operating in the Ku <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</i> band are arranged in a regular array configuration. Two orthogonal probes share a common radiating patch structure and are fed by two <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$H$ </tex-math></inline-formula> -shaped coupling slots. Sidewall metalized cavity waveguide elements operating in the W-band are fed by a substrate-integrated waveguide and arranged in a sparse array configuration, which is based on an optimization algorithm proposed in this work. Furthermore, the feeding locations are regularly determined, which is beneficial to transceiver/receiver design, thus reducing the cost of a phased array system. By exploiting this compact array topology and optimization algorithm, two-phased arrays with a large frequency ratio employing a shared aperture simultaneously exhibit wide-angle scanning properties. A 64-element array is designed, fabricated, and measured. The measurement results show that the Ku-band dual-polarized antenna exhibits a wide impedance bandwidth of 20% in the 14.3–17.6 GHz frequency range for two orthogonal polarizations and high isolation (>20 dB) between the feeding ports. The W-band antenna exhibits a 5.4% fractional impedance bandwidth covering 90–95 GHz frequency range with a ±45° scanning angle in the E <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</i> and H-planes.

Topographical Analysis of Aneurysm Wall Enhancement With 3-Dimensional Mapping.

Aneurysm wall enhancement has been identified as a potential biomarker for aneurysm instability. Enhancement has been determined by different approaches on 2D multiplanar views. This study describes a new method to quantify enhancement through 3D heatmaps and histograms. A custom algorithm was developed using orthogonal probes extending from the aneurysm lumen into the wall to create 3D heatmaps and histograms of wall enhancement on 7T-MRI. Three quantitative metrics for general, specific, and focal wall enhancement were generated from the histograms. Thirty-two aneurysms were analyzed and classified based on 3D heatmaps and histograms. Larger aneurysms were more enhancing (Spearman's r=0.472, p=0.006), and had more heterogeneous enhancement (Spearman's r=0.557, p<0.001) than smaller aneurysms. Patterns of enhancement differed between saccular, fusiform, and thrombosed aneurysms. Fusiform aneurysms were larger (p=0.015) and had more heterogenous enhancement compared to saccular aneurysms. Fusiform aneurysms had more areas of focal enhancement (p<0.001) and right skewed histograms (p=0.003). The 3D analysis of aneurysm wall enhancement provides topographic data of the entire aneurysm wall. New metrics developed based on this method showed that large and fusiform aneurysms have heterogenous enhancement.

Material-specific high-resolution table-top extreme ultraviolet microscopy

Microscopy with extreme ultraviolet (EUV) radiation holds promise for high-resolution imaging with excellent material contrast, due to the short wavelength and numerous element-specific absorption edges available in this spectral range. At the same time, EUV radiation has significantly larger penetration depths than electrons. It thus enables a nano-scale view into complex three-dimensional structures that are important for material science, semiconductor metrology, and next-generation nano-devices. Here, we present high-resolution and material-specific microscopy at 13.5 nm wavelength. We combine a highly stable, high photon-flux, table-top EUV source with an interferometrically stabilized ptychography setup. By utilizing structured EUV illumination, we overcome the limitations of conventional EUV focusing optics and demonstrate high-resolution microscopy at a half-pitch lateral resolution of 16 nm. Moreover, we propose mixed-state orthogonal probe relaxation ptychography, enabling robust phase-contrast imaging over wide fields of view and long acquisition times. In this way, the complex transmission of an integrated circuit is precisely reconstructed, allowing for the classification of the material composition of mesoscopic semiconductor systems.

Technical note: Turbulence measurements from a light autonomous underwater vehicle

Abstract. A self-contained turbulence instrument from Rockland Scientific was installed on a light autonomous underwater vehicle (AUV) from OceanScan Marine Systems and Technology Lda. We report on the data quality and discuss limitations of dissipation estimated from two shear probes during a deployment in the Barents Sea in February 2021. The AUV mission lasted for 5 h, operating at a typical horizontal speed of 1.1 m s−1. The AUV was programmed to find and cross the maximum along-path thermal gradient at 10, 20 and 30 m depths along 4 km transects. Although the AUV vibrations contaminate the shear probe records, the noise is mitigated by removing vibration-induced components from shear spectra using the accelerometer signal measured in multiple directions. Dissipation rate estimates in the observed transects varied in the range 1×10-8 and 6×10-6 W kg−1, with the values from the two orthogonal probes typically in agreement to within a factor of 2. Dissipation estimates from the AUV show good agreement with nearby vertical microstructure profiles obtained from the ship during the transects, indicating that the turbulence measurements from the AUV are reliable for this relatively turbulent environment. However, the lowest reliable dissipation rates are limited to 5×10-8 W kg−1, making this setup unfit for use in quiescent environments.

Abstract 13: 3D-Map Analysis Of Symptomatic Intracranial Atherosclerotic Plaques

Background: The study of plaque enhancement using high resolution vessel wall imaging can provide useful prognostic data. However, this analysis is hindered by plaque sampling and methodological constrains. We developed a new method to quantify plaque enhancement with 3D map analysis. Methods: Ultra-high resolution (7 Tesla) vessel wall imaging was performed on 41 patients with history of symptomatic atherosclerotic disease. Culprit and non-culprit plaques were analyzed. 3D reconstructions of culprit (N=41) and non-culprit plaques (N=14) was performed on T1 and T1+Gd images. Using an in-house code, orthogonal probes were extended from the lumen of the vessel into the arterial wall (Figure). In this way, the entire wall was sampled with multiple spokes. These values were then normalized to the corpus callosum (CC) to obtain a signal intensity ratio (SI ratio ). Dynamic contrast uptake was quantified as the change in mean SI of the plaque after contrast administration. Results: Forty one culprit and 14 non-culprit plaques (N=55) were analyzed. Culprit plaques enhanced with gadolinium (Gd) more significantly (SI plaque = 0.76 ± 0.28) than non-culprit plaques (SI plaque =0.58 ± 0.14) (p=0.05). In addition, culprit plaques displayed more contrast uptake (ΔSI plaque =0.33±0.25) than non-culprit plaques (ΔSI plaque =0.19 ± 0.08,p=0.01). Conclusion: 3D analysis of plaque enhancement with ultra-high resolution MRI is a promising technique that may be used as a biomarker of culprit intracranial atherosclerotic plaques. In addition, quantifying the dynamic plaque contrast uptake may provide more insight into the biology of these lesions.Figure. Magnified 7T coronal view of a basilar artery plaque pre (A) and post administration of Gd (B). 3D analysis of the dynamic uptake of Gd in T1 (C) and T1 + Gd (D). This plaque had a of 0.49 = highly enhancing.

Kinetically Orthogonal Probe for Simultaneous Measurement of H2S and Nitroreductase: A Refined Method to Predict the Invasiveness of Tumor Cells

The concentrations of nitroreductase and H2S have been widely used to predict the invasiveness of tumors. However, the above two substrates always interfere with the measurement of each other as both substrates react with the typical nitroaromatic probe with the same process. Moreover, the above interferences may lead to the misjudgment of the tumor invasiveness. We used a strategy combining kinetical distinguishing and signal amplification to construct a kinetically orthogonal probe labeled KOP. The above strategy expanded the gap between the reactivity of KOP to H2S and nitroreductase with an acceptable reactivity and could determine the concentration of coexisting nitroreductase and H2S on a kinetic curve with a breakpoint. KOP could also indicate the correct invasiveness tendency in the cellular model with a complex H2S generation pathway, while the traditional kinetically nonorthogonal probe could not indicate invasiveness correctly.

Channel-multiplexing for quasi-distributed acoustic sensing with orthogonal codes.

With the increasing demands for large-scale acoustic sensing in many important fields such as hydrophone, vehicle tracking and pipeline monitoring, optical fiber-based distributed acoustic sensing (DAS) has experienced a rapid development. In recent years, quasi-distributed acoustic sensing (QDAS) based on single mode fiber with enhanced point array has emerged, which is a good approach to improve signal-to-noise ratio and deal with the interference-fading problem in DAS. However, similar to DAS, the performance of QDAS is also limited by the finite frequency domain resources. To break the trade-off between sensing bandwidth and distance, additional frequency domain resources are always needed to multiplex the sensing channel. Multiple-input multiple-output coding technology is an approach to realize QDAS channel-multiplexing with the orthogonal probe waves in the same frequency band. In this paper, the iteration constrain condition of the orthogonal codes is modified, and the generation method of more orthogonal codes with high and consistent suppression ratio for QDAS is provided. In the demonstration experiment, the QDAS has successfully achieved 5 times the sensing bandwidth expansion on a 5.19 km fiber based on 5 new orthogonal codes on the same frequency, with 5 m spatial resolution and 10 p ε/H z strain noise level.

Diverse functional elements in RNA predicted transcriptome-wide by orthogonal RNA structure probing.

RNA molecules can fold into complex structures and interact with trans-acting factors to control their biology. Recent methods have been focused on developing novel tools to measure RNA structure transcriptome-wide, but their utility to study and predict RNA-protein interactions or RNA processing has been limited thus far. Here, we extend these studies with the first transcriptome-wide mapping method for cataloging RNA solvent accessibility, icLASER. By combining solvent accessibility (icLASER) with RNA flexibility (icSHAPE) data, we efficiently predict RNA-protein interactions transcriptome-wide and catalog RNA polyadenylation sites by RNA structure alone. These studies showcase the power of designing novel chemical approaches to studying RNA biology. Further, our study exemplifies merging complementary methods to measure RNA structure inside cells and its utility for predicting transcriptome-wide interactions that are critical for control of and regulation by RNA structure. We envision such approaches can be applied to studying different cell types or cells under varying conditions, using RNA structure and footprinting to characterize cellular interactions and processing involving RNA.

Achieving high spatial resolution in a large field-of-view using lensless x-ray imaging

X-ray ptychography, a powerful scanning lensless imaging technique, has become attractive for nondestructively imaging internal structures at nanoscale. Stage positioning overhead in conventional step-scan ptychography is one of the limiting factors on the imaging throughput. In this work, we demonstrate the use of advanced fly scan ptychography to achieve high-resolution ptychograms of modern integrated circuits on a large field-of-view at millimeter scale. By completely removing stage overheads between scan points, the imaging time for millimeter-size sample can be significantly reduced. Furthermore, we implement the orthogonal probe relaxation technique to overcome the variation of illumination across the large scan area as well as local vibrations. The capability of x-ray ptychography shown here is broadly applicable for various studies, which requires both high spatial resolution and large scan area.

Red‐ and Far‐Red‐Emitting Zinc Probes with Minimal Phototoxicity for Multiplexed Recording of Orchestrated Insulin Secretion

AbstractZinc biology, featuring intertwining signaling networks and critical importance to human health, witnesses exciting opportunities in the big data era of physiology. Here, we report a class of red‐ and far‐red‐emitting Zn2+ probes with Kd values ranging from 190 nM to 74 μM, which are particularly suitable for real‐time monitoring the high concentration of Zn2+ co‐released with insulin during vesicular secretory events. Compared to the prototypical rhodamine‐based Zn2+ probes, the new class exploits morpholino auxochromes which eliminates phototoxicity during long‐term live recording of isolated islets. A Si‐rhodamine‐based Zn2+ probe with high turn‐on ratio (&gt;100), whose synthesis was enabled by a new route featuring late‐stage N‐alkylation, allowed simultaneous recording of Ca2+ influx, mitochondrial signal, and insulin secretion in isolated mouse islets. The time‐lapse multicolor fluorescence movies and their analysis, enabled by red‐shifted Zn2+ and other orthogonal physiological probes, highlight the potential impact of biocompatible fluorophores on the fields of islet endocrinology and system biology.

Red- and Far-Red-Emitting Zinc Probes with Minimal Phototoxicity for Multiplexed Recording of Orchestrated Insulin Secretion.

Zinc biology, featuring intertwining signaling networks and critical importance to human health, witnesses exciting opportunities in the big data era of physiology. Here, we report a class of red- and far-red-emitting Zn2+ probes with Kd values ranging from 190 nM to 74 μM, which are particularly suitable for real-time monitoring the high concentration of Zn2+ co-released with insulin during vesicular secretory events. Compared to the prototypical rhodamine-based Zn2+ probes, the new class exploits morpholino auxochromes which eliminates phototoxicity during long-term live recording of isolated islets. A Si-rhodamine-based Zn2+ probe with high turn-on ratio (>100), whose synthesis was enabled by a new route featuring late-stage N-alkylation, allowed simultaneous recording of Ca2+ influx, mitochondrial signal, and insulin secretion in isolated mouse islets. The time-lapse multicolor fluorescence movies and their analysis, enabled by red-shifted Zn2+ and other orthogonal physiological probes, highlight the potential impact of biocompatible fluorophores on the fields of islet endocrinology and system biology.

Multicomponent Bioluminescence Imaging with Naphthylamino Luciferins.

Bioluminescent tools have been used for decades to image processes in complex tissues and preclinical models. However, few distinct probes are available to probe multicellular interactions. We and others are addressing this limitation by engineering new luciferases that can selectively process synthetic luciferin analogues. In this work, we explored naphthylamino luciferins as orthogonal bioluminescent probes. Three analogues were prepared using an optimized synthetic route. The luciferins were found to be robust emitters with native luciferase in vitro and in cellulo. We further screened the analogues against libraries of luciferase mutants to identify unique enzyme-substrate pairs. The new probes can be used in conjunction with existing bioluminescent tools for multi-component imaging.

Моделювання взаємодії космічних апаратів з іоносферною розрідженою плазмою

Principles of simulation of the physical-chemical and electromagnetic interaction of a spacecraft with the near-satellite environment and principles of probe diagnostics of rarefied plasma flows onboard a spacecraft are stated. Equivalence criteria are formulated for the interaction of a spacecraft with the near-satellite environment and hypersonic rarefied plasma flows on dedicated setups, in particular on the plasmaelectrodynamic setup of the Institute of Technical Mechanics of the National Academy of Sciences of Ukraine and the State Space Agency of Ukraine, which has the status of the National Patrimony of Ukraine. The features of spacecraft interaction with the near-satellite environment were studied along the following three lines: - degradation of the materials and performance characteristics of spacecraft components in a long-term orbital service: - magnetohydrodynamic interaction of a spacecraft with hypersonic rarefied plasma flows; - probe diagnostic of rarefied plasma flows onboard a spacecraft. Along the first line, a calculation-and-experiment procedure was developed to evaluate the power decrease of spacecraft silicon solar batteries under long-term (~ 10 years) exposure to the space factors and the near-satellite environment in circular orbits. Principles of accelerated life tests for the resistance of spacecraft polymer materials to long-term exposure to atomic oxygen flows and vacuum ultraviolet radiation were developed. Simultaneous exposure of polymers to atomic oxygen and vacuum ultraviolet radiation results in the synergic effect of mass loss by materials that contain a monomer of the (CH)n group. Along the second line, models were formulated for magnetohydrodynamic interaction in the magnetized spacecraft – ionospheric plasma system. It was shown that the interaction of a ?0,8 – 1.5 T magnetic field of a space debris object (in particular, a spent spacecraft) with the ionospheric plasma produces an electromagnetic drag force sufficient for removing it to a low orbit followed by its burn-up in the dense atmosphere. Along the third line, procedures were developed for ionospheric plasma probe diagnostics using onboard instrumentation that includes mutually orthogonal cylindrical electrical probes and a two-channel neutral-particle detector. It was shown that this instrumentation with the use of proprietary output signal interpretation algorithms and procedures allows one to locate sources of space-time disturbances in inospheric plasma parameters caused by natural and technogeneous catastrophic phenomena on the subsatellite track.

Joint Doppler Frequency and Direction of Arrival Estimation for TDM MIMO Automotive Radars

This paper considers a novel approach to joint estimation of the velocity (or Doppler frequency) and Direction of Arrival (DOA) of targets by time division multiplexing (TDM) multiple-input multiple-output (MIMO) radars in automotive applications. The TDM MIMO radars create orthogonal probing signals (in time domain) by allocating a transmitter to a separate time slot. In this paper, we consider a standard TDM MIMO radar to be the one where transmitters are activated sequentially according to their natural spatial order. The drawback of the standard TDM MIMO approach is the coupling of velocity and DOA information of the targets. The coupling reduces the unambiguous estimation interval of the Doppler frequencies of the targets by the number of transmit antennas being multiplexed. In this paper, we propose a novel cost function to jointly estimate both the Doppler frequency and the DOA of each target by reinstating the reduced unambiguous Doppler spectrum interval. Our approach is generally applicable to solve the Doppler ambiguity problems associated with any colocated standard TDM MIMO radar. To confirm this, we present the simulation results that evaluate the performances of two widely deployed TDM MIMO radar antenna configurations: non-overlapped and overlapped arrays. Moreover, we derive the analytical expressions to study the statistical performance of the proposed method. The simulation examples are presented to verify the performance of the proposed method as well as the accuracy of the analytical expressions.

Coupling of ethanolamine ammonia-lyase protein and solvent dynamics characterized by the temperature-dependence of EPR spin probe mobility and dielectric permittivity.

Electron paramagnetic resonance (EPR) spectroscopy is used to address the remarkable persistence of the native Arrhenius dependence of the 2-aminopropanol substrate radical rearrangement reaction in B12-dependent ethanolamine ammonia-lyase (EAL) from Salmonella typhimurium from physiological to cryogenic (220 K) temperatures. Two-component TEMPOL spin probe mobility in the presence of 10 mM (0.08% v/v) 2-aminopropanol over 200-265 K demonstrates characteristic concentric aqueous-cosolvent mesodomain and protein-associated domain (PAD, hydration layer) solvent phases around EAL in the frozen solution. The mesodomain formed by the relatively small amount of 2-aminopropanol is highly confined, as shown by an elevated temperature for the order-disorder transition (ODT) in the PAD (230-235 K) and large activation energy for TEMPOL rotation. Addition of 2% v/v dimethylsulfoxide expands the mesodomain, partially relieves PAD confinement, and leads to an ODT at 205-210 K. The ODT is also manifested as a deviation of the temperature-dependence of the EPR amplitude of cob(II)alamin and the substrate radical, bound in the enzyme active site, from Curie law behavior. This is attributed to an increase in sample dielectric permittivity above the ODT at the microwave frequency of 9.5 GHz. The relatively high frequency dielectric response indicates an origin in coupled protein surface group-water fluctuations of the Johari-Goldstein β type that span spatial scales of ∼0.1-10 Å on temporal scales of 10-10-10-7 s. The orthogonal EPR spin probe rotational mobility and solvent dielectric measurements characterize features of EAL protein-solvent dynamical coupling and reveal that excess substrate acts as a fluidizing cryosolvent to enable native enzyme reactivity at cryogenic temperatures.

A Compact Cavity-Backed Tri-Band Antenna Design for Flush Mount GNSS (L1/L5) and SDARS Operations

This letter presents a unique compact cavity-backed tri-band antenna design for supporting simultaneous Global Navigation Satellite System (GNSS) ( L 1/ L 5) and Satellite Digital Audio Radio Service (SDARS) operations in a rooftop flush mount configuration. The cavity dimensions are 100 mm in diameter and only 9.35 mm in depth to meet a specific automobile manufacturer's physical dimension requirement. The achieved half-power realized gain bandwidths at L1, L5, and SDARS bands are 85, 54, and 250 MHz, respectively. This design consists of a bottom feeding board, a top GNSS board, and a middle SDARS board. All three boards are connected using vertical wires. The left-hand circular polarization (LHCP) SDARS element is a C-line coupled circular patch element that is excited via a novel traveling-wave proximity-coupling method that maximizes the passage of the out-of-band signals. The right-hand circular polarization (RHCP) dual-ring GNSS element is excited after the SDARS element using two orthogonal tapered-width proximity probes which are connected to two microstrip lines with different lengths for producing 90° phase difference at 1.4 GHz. The entire antenna assembly is connected to a single subminiature version A (SMA) connector. The design specifications and operating principles of the proposed antenna are discussed along with comparisons between the simulation and measurement performance obtained from a fabricated prototype.

Orthogonal Bioluminescent Probes from Disubstituted Luciferins.

Bioluminescence imaging with luciferase-luciferin pairs is routinely used to monitor cellular functions. Multiple targets can be visualized in tandem using luciferases that process unique substrates, but only a handful of such orthogonal probes are known. Multiplexed studies require additional robust, light-emitting molecules. In this work, we report new luciferins for orthogonal imaging that comprise disubstituted cores. These probes were found to be bright emitters with various engineered luciferases. The unique patterns of light output also provided insight into enzyme-substrate interactions necessary for productive emission. Screening studies identified mutant luciferases that could preferentially process the disubstituted analogues, enabling orthogonal imaging with existing bioluminescent reporters. Further mutational analyses revealed the origins of substrate selectivity. Collectively, this work provides insights into luciferase-luciferin features relevant to bioluminescence and expands the number of probes for multicomponent tracking.

Sidewall Imaging of Microarray-Based Biosensor Using an Orthogonal Cantilever Probe

We proposed a novel atomic force microscopy (AFM) technique based on the orthogonal cantilever probe (OCP) for measuring the sidewall of microstructure/nanostructure. The OCP mainly consists of a horizontal arm and a vertical arm with a protruding tip, where the vertical arm is orthogonally assembled on the end side of the horizontal arm. Therefore, the interaction force between the tip and the sample can be detected by the torsion signal of the OCP. This new technique is capable of scanning the steep sidewall in the torsional mode of the OCP and mapping the horizontal surface by the bending deformation of the OCP. Theoretical calculation and finite-element analysis (FEA) were first used to design and determine the reasonable parameters of the OCP. Then, the designed OCP was prepared by focused ion beam (FIB) milling and microassembly technique, and the dynamic and static properties of the OCP were studied for obtaining its performance parameters. A gold-silicon interface and a microcomb structure were used to verify its ability to image with high precision. Finally, a biosensor based on the 3-D microarray was imaged by the OCP to study its uniformity of the surface modification on three representative positions (sidewall, top, and bottom). Meanwhile, the top and bottom of the microarray were also measured by the conventional AFM method with a commercial probe, which verified the credibility and powerful capabilities of the proposed OCP. Experimental results showed that the sidewall roughness of the biosensor is significantly smaller, which means that the surface modification effect is different from other positions.