Dielectric Imaging Research Articles

Terahertz super-resolution imaging with large depth of field enabled by the terajet of bilayer dielectric spheres

Terahertz imaging has found extensive applications in non-destructive testing, security inspection, and other various fields. Intensive research on terahertz imaging systems has been executed to pursue high performance on imaging resolution and depth of field (DOF). However, the terahertz imaging systems with both high imaging resolution and large DOF have rarely been reported. In this paper, a mesoscopic-sized dielectric bilayer sphere-assisted super-resolution imaging method was proposed to simultaneously achieve enormously improved imaging resolution and extended DOF. Simulation analyses revealed that the ultrathin and long terajets were generated by the well-designed bilayer sphere. The THz super-resolution image for the samples can be captured by the point-by-point terajet scanning. The experimental results demonstrated that the best resolution reached up to 0.4λ, the DOF with super-resolution was up to 2λ, and the DOF with sub-wavelength resolution was up to 4λ. This method holds great potential for widespread application in terahertz imaging and detection, especially for curved or complex sample structures.

Pesticide uptake and translocation in plants monitored in situ via laser ablation dielectric barrier discharge ionization mass spectrometry imaging

For reducing pesticide usage and enhancing the effectiveness of pest control, it is necessary to elucidate the mechanisms of pesticide uptake and translocation in plants. Here, atmospheric pressure laser ablation dielectric barrier discharge ionization mass spectrometry imaging (LA-DBDI-MSI) was used to for in-situ monitoring of pesticide uptake and translocation in plants with a spatial resolution of 25 μm, and only requiring minimal or no sample preparation. Roots and leaves of tomato plants that had been exposed to a systemic pesticide, difenoconazole, were studied. From MSI data of tomato leaves, we found that difenoconazole was mainly distributed in the leaf veins after 6 days of pesticide exposure, but distributed throughout the leaf after 10 days of pesticide exposure. Endogenous substances are mainly distributed in the mesophyll, but are not present in the veins. This study clarifies the uptake and translocation mechanism of pesticides in plants, which is of great significance for reducing the dosage of pesticides and improving the effect of plant disease control.

Dielectric Lens-Based Millimeter Wave Imaging for Concealed Object Detection in Security Applications

Dielectric Lens-Based Millimeter Wave Imaging for Concealed Object Detection in Security Applications

Free-Space Time-Domain Approach for Dielectric Imaging of Biological Tissues

Free-Space Time-Domain Approach for Dielectric Imaging of Biological Tissues

Accuracy of the Injection-Based Occlusion Tool Utilizing Saline and Glucose Solution in Cryoballoon Ablation Guided by a Novel Dielectric Imaging System.

Introduction: The aim of this study is to assess the accuracy of the injection-based occlusion (IBO) tool utilizing saline and glucose solution in verifying pulmonary vein (PV) occlusion during cryoballoon ablation guided by a novel dielectric system (KODEX-EPD system). Methods: In this retrospective study, we enrolled 34 consecutive patients with paroxysmal atrial fibrillation (AF) who underwent their initial cryoballoon ablation procedure guided by the KODEX-EPD system. PV occlusion was firstly assessed by the IBO tool utilizing saline or glucose solution and then verified by direct contrast angiography. Patients were divided into two groups according to the fluid used in the IBO tool: the Saline Group and the Glucose Group. Results: The overall procedure time and fluoroscopy time were comparable between the Saline Group and the Glucose Group (113.7 ± 18.3 vs. 108.4 ± 15.9 min; p = 0.375 and 10.1 ± 3.7 vs. 9.3 ± 3.5 min; p = 0.559). The IBO tool was utilized a total of 138 times in the Saline Group and 135 times in the Glucose Group. When assessing PV occlusion, the IBO tool using saline demonstrated a sensitivity of 92.6% and a specificity of 95.2% compared to angiography. Similarly, the IBO tool utilizing glucose solution showed a sensitivity of 93.2% and a specificity of 96.1%. Conclusions: The IBO tool utilizing non-contrast fluid, saline and glucose solution, demonstrates a high level of sensitivity and specificity in accurately predicting PV occlusion during cryoablation procedures. Both the saline and glucose solutions used in the IBO tool show promising results in effectively assessing PV occlusion.

Optical edge-enhanced imaging based on dielectric metasurfaces

Optical edge-enhanced imaging is an effective method for boundary extraction, and it is also a cutting-edge technology for object detection in image processing. With the rapid development of metamaterial and metasurface fields, the miniaturization and lightweight of optical devices have reached a new scale. At present, the experimental research of optical edge-enhanced imaging using metasurface is insufficient and lags behind the theoretical research. In this paper, we propose optical edge-enhanced imaging based on a Huygens phase metasurface in the near-infrared (NIR). The entire optical edge-enhanced process is simulated, and the feasibility of the method is verified theoretically. Then, the edge-enhanced of numbers, letters, and biological tissues is carried out experimentally, and the results are consistent with the simulation results. This study proposes a near-infrared dielectric metasurface-based edge-enhanced imaging that can find important applications in compact optical platforms such as image processing.

Achieving a very low fluoroscopy exposure in cryoballon ablation of the pulmonary veins: learning curve of 3D-wide-band dielectric mapping guided ablation

Abstract Funding Acknowledgements Type of funding sources: None. Background Pulmonary vein isolation (PVI) using cryoballoon (CB) ablation is associated with an increased radiation exposure compared with radiofrequency ablation. The novel high resolution wide-band dielectric imaging system improved our strategy of radiation exposure reduction without affecting acute efficacy and safety and giving additional insights on the atrial voltage mapping of the selected patients. Purpose To evaluated the reduction of fluoroscopy use over time during consecutive CB PVI performed with the use of a new 3D mapping system. Methods The study population comprised 89 consecutive patients who underwent in our Centre between Juni 2021 and Juli 2022 to third-generation CB-based PVI with the wide band dielectric system and X-Ray System with enhanced collimation, frame reduction and stored fluoroscopy. All included patients gave written informed consent for TEE and PVI and agreed to the anonymous evaluation of their data for research and quality control. We analyzed the reduction in fluoroscopy use among time. Results The mean radiation exposure data among all patients demonstrate a significant reduction compared with the literature data od CB-PVI: mean fluoroscopy time 3,95 ± 4,12 minutes and mean DAP 15,45 ± 27,18 cGy*cm2. Analysing the learning curve, we identified every 30 patients a significant reduction in X-Ray use achieving a reduction of ca. 80% in the last group of patients compared with the former one. The results are summarized in the Table and Graph. No major complications occurred Conclusion The analysis of the fluoroscopy utilization and exposure during CB-PVI performed with a novel 3D mapping system using wide-band dielectric imaging demonstrated a significant learning curve. A stepwise progressive reduction can be identified leading to a reduction of ca. 80% of radiation use among the last 30 procedures compared to the first 30 ones reflecting individual and team proficiency in using the new imaging system. A very low-radiation exposure during CB-PVI can be achieved with this approach.

Minimizing radiation in cryoballon-based ablation of the pulmonary veins through a novel high-resolution wide-band dielectric imaging system

Abstract Funding Acknowledgements Type of funding sources: None. Purpose Pulmonary vein isolation (PVI) using cryoballoon (CB) ablation is associated with an increased radiation exposure compared with radiofrequency ablation. The novel high resolution wide-band dielectric imaging system improved our strategy of radiation exposure reduction without affecting acute efficacy and safety and giving additional insights on the atrial voltage mapping of the selected patients. We evaluated the procedural data of patients undergoing CB PVI with this new 3D electroanatomic mapping system Methods The study population comprised 89 consecutive patients who underwent third-generation CB-based PVI with the wide band dielectric system and X-Ray System with enhanced collimation, frame reduction and stored fluoroscopy. All the transeptal manouver were perfomed under transesofageal guidance. Our data were compared to the literature data regarding radiation exposure and fluoroscopy time during CB based PVI without the use of 3D electroanatomic mapping. Primary endpoints were the total dose area product (DAP) and the fluoroscopy time. Results Our mean DAP per procedure has been 15,45 ± 27,18 cGy*cm2, challenging the mean DAP in the recent literature from two high volume centers being about 389 to 1129 cGy*cm2 in CB based PVI. Our median fluoroscopy time was 3,95 ± 4,12 minutes, again challenging the mean fluoroscopy time reported in the literature of around 10 to 14,5 minutes in both CB PVI. Our mean mapping left atrium mapping time using Kodex was of about 7 minutes. No major complications occurred. Conclusion The combined use of an optimized fluoroscopy setting and a novel high resolution wide-band dielectric imaging system in CB based PVI can significantly reduce radiation exposure and fluoroscopy time and is associated to a high procedural safety.

Development of General-purpose Dielectric Constant Imaging Unit for SEM and Direct Observation of Samples in Aqueous Solution.

Electron microscopes can observe samples with a spatial resolution of 10 nm or higher; however, they cannot observe samples in solutions due to the vacuum conditions inside the sample chamber. Recently, we developed a scanning electron-assisted dielectric microscope (SE-ADM), based on scanning electron microscope, which enables the observation of various specimens in solution. Until now, the SE-ADM system used a custom-made SE-ADM stage with a built-in amplifier and could not be linked to the scanning electron microscopy (SEM) operation system. Therefore, it was necessary to manually acquire images from the SE-ADM system after setting the EB focus, astigmatism, and observation field-of-view from the SEM operating console. In this study, we developed a general-purpose dielectric constant imaging unit attached to commercially available SEMs. The new SE-ADM unit can be directly attached to the standard stage of an SEM, and the dielectric signal detected from this unit can be input to the external input terminal of the SEM, enabling simultaneous observation yielding SEM and SE-ADM images. Furthermore, 4.5 nm spatial resolution was achieved using a 10 nm thick silicon nitride film in the sample holder in the observation of aggregated PM2.5. We carried out the observation of cultured cells, PM2.5, and clay samples in solution.

Abstract 12149: Assessment of Cryoballoon Occlusion Shift From the Pulmonary Vein Ostium Following Freeze Initiation Using a Dielectric Imaging System

Introduction: Cryoballoon ablation for atrial fibrillation (AF) has been widely adopted clinically. However, dislodgement from the pulmonary vein (PV) ostium following freeze initiation commonly occurs due to a sudden rise in balloon pressure, known as the “pop-out” phenomenon. This can often only be partially detected using continuous color Doppler or repeat angiography after the initiation of freeze. We aim to access the incidence of this phenomenon using the dielectric imaging system in comparison to intracardiac echocardiography (ICE). Methods: Ten patients underwent de novo cryoballoon ablation for paroxysmal or persistent AF with the use of the KODEX-EPD dielectric imaging system (Philips, Amsterdam, Netherlands). A baseline assessment and injection were performed pre-ablation followed by analysis of occulsion via the KODEX Occlusion Viewer. Simultaneous assessment was performed by the operator utilizing ICE. Repeat assessment with injection was performed after ablation start to assess whether the cryoballoon remained occluded on ICE and by KODEX’s occlusion assessment. Results: There was a high correlation between KODEX and ICE for assessment of balloon occlusion prior to ablation (91.7±23.6%). KODEX demonstrated an overall sensitivity (88.6%), specificity (75.0%), positive predictive value (76.5%), and negative predictive value (87.8%) of the occlusion tool validated by ICE. Both imaging modalities detected a leak after initial full occlusion, an incidence of 24.3% on Kodex and 23.8% on ICE. Conclusions: Balloon contact with the PV is vital for an effective, transmural lesion. The dielectric imaging system and ICE confirmed high incidence of this “pop-out” phenomenon, which can lead to incomplete PV isolation. The KODEX-EPD occlusion tool is highly sensitive and specific to assist in the identification of this phenomenon and may improve the outcome for cryoballoon procedures. In the future a more compliant cryoballoon design, without a shift in balloon pressure during ablation, may avoid this phenomenon.

A novel wide-band dielectric imaging system to guide radiofrequency ablation for pulmonary vein isolation.

Recently, the wide-band dielectric mapping system Kodex-EPD was introduced. This study reports the first clinical experience using a novel system to guide pulmonary vein isolation (PVI) with radiofrequency (RF)ablation. METHODSAND RESULTS: The study included 20 consecutive patients undergoing de-novo PVI for symptomatic paroxysmal or persistent atrial fibrillation guided by Kodex-EPD. The primary efficacy endpoint was successful PVI. Secondary endpoints included procedural parameters and complications. In all 20 patients (mean age 68 ± 8 years, 12 male patients, paroxysmal fibrillation in 14/20 [70%] patients), PVI was successfully completed. One patient underwent additional cavo-tricuspid isthmus ablation for concomitant typical atrial flutter and one patient required additional ablation of a focal atrial tachycardia. A conventional three-dimensional image of the left atrium as well as the innovative endocardial panoramic view were used to guide catheter manipulation and ablation. Median procedure time was 115 [1st; 3rd quartile 93,75; 140] min and median total fluoroscopy time was 9.9 [9.7; 11.2] min, of which a median of 0.8 [0.6; 0.9] min was required to create left atrial maps. Complete left atrial imaging using Kodex-EPD was achieved within a median of 7.1 [5.7; 8.3] min. Median RFablation time was 45.1 [34.6; 58.7] min. No major complications were observed. RF ablation PVI guided by Kodex-EPD seems safe and feasible. The system provides effective three-dimensionalguidance for PVI.

Feasibility of wideband dielectric imaging to guide temperature-controlled atrial fibrillation ablation.

The DiamondTemp (DT) radiofrequency (RF) ablation catheter (Medtronic, Dublin, Ireland) has been introduced for atrial fibrillation (AF) ablation. It features 6 thermocouples at its tip, imbedded in a synthetic diamond material that offers high thermal diffusivity. The technology allows temperature-controlled ablation combining high ablation power levels with a direct temperature feedback consequently resulting in homogeneous atrial lesion formation.1 Recently, a novel wideband dielectric imaging system (KODEX-EPD, EPD Solutions, Philips, Amsterdam, The Netherlands) was introduced to guide catheter ablation of cardiac arrhythmias.

A Novel Wide-band Dielectric Imaging System for Electro-anatomic Mapping and Monitoring in Radiofrequency Ablation and Cryoablation.

A novel wide-band dielectric mapping system, named as KODEX-EPD (EPD Solutions, Philips, Best, the Netherlands), was effectively used in the EA mapping for atrial fibrillation (AF) ablation. To date, only a few studies have concentrated on the application of the KODEX-EPD system for ablating supraventricular tachycardia or ventricular premature beats (VPBs) in human models. This study aims to assess the applicability and efficiency of a novel three-dimensional electro-anatomic (EA) mapping system to improve the success rate of ablation. This study included 11 consecutive patients who underwent ablation after EA mapping with the KODEX-EPD system. All surgeries were successfully performed using the KODEX-EPD system, including 6 cases who underwent ablation of paroxysmal supraventricular tachycardia (PSVT), 2 cases who received ablation of VPBs from right ventricular outflow tract (RVOT), and 3 cases who underwent cryoablation of AF. For ablation of PSVT or VPBs, the operation time was 31.4 (range, 24.0-38.0) min, in which a median operation time of 2.9 min was used to create anatomic images, and the median fluoroscopic dose was 7.4 mGy. For ablation of AF, the operation time was 56.0 (range, 49.0-62.0) min, in which a median of 4.3 (range, 3.4-5.2) min was used for constructing left atrium map, and the median fluoroscopic dose was 15.0 mGy. The operation time and the fluoroscopic dose were greatly shortened for all surgeries. The KODEX-EPD system is an effective and safe tool to guide the EA mapping, leading to improvement in the success rate of ablation. It can promote the ablation process with the reduced fluoroscopic dose, and it is also a promising tool for complex surgeries.

Cryoballoon ablation guided by a novel wide-band dielectric imaging system.

Background and aimTo investigate the feasibility, acute efficacy, periprocedural safety, and procedural parameters of CB-based PVI guided by KODEX-EPD using different occlusion tool software versions.Methods and resultsA total of 173 patients (60/173 (35%) paroxysmal AF, 64 ± 12 years, 66/173 (38%) female), underwent CB-based PVI guided by KODEX-EPD between August 2019 and October 2021. Acute PVI was achieved in all the patients. Total fluoroscopy time and dye volume were 13.9 [10.6–19.4] min and 47.5 [20–70] ml. Periprocedural complications occurred in 3 (2%) of the 173 patients. As part of the continued development program, different software versions were used, including 1.4.6 on 38 (22%), 1.4.6a on 33 (19%), 1.4.7 on 41 (24%), and 1.4.8 on 61 (35%) of the patients. Outcomes were compared between software versions by a univariate analysis. Sensitivity analyses were performed to account for confounders. Median fluoroscopy time was decreased by 6.4 min (37.3%), and the median volume of dye was decreased by 32.5 ml (52%) from versions 1.4.6 to 1.4.8. Software version was a significant predictor of fluoroscopy time and dye volume, while reductions in procedure duration and dose area product were observed but mainly explained via confounders.ConclusionCB-based PVI guided by KODEX-EPD is feasible and safe. Progressive software improvements appear to be associated with lower fluoroscopy duration and dye use. Further studies are needed to evaluate the advantage of KODEX-EPD-guided compared to conventional CB-PVI.

Novel tissue-pressure sensing technology using a wide-band dielectric imaging system: An in vivo study

BackgroundA novel dielectric wide-band imaging system with tissue pressure (TP) technology provides real-time contact force (CF) monitoring using non-CF catheters. This study sought to investigate the feasibility, safety, and efficacy of ablation with TP technology. MethodsEighty-five patients with supraventricular tachycardia (SVT) were ablated with real-time monitoring of CF by TP technology and compared with 85 patients who underwent ablation with a conventional non-TP approach. Baseline characteristics, procedural data, and TP data were analyzed in the study. Ablation applications in the TP group were then subdivided into good contact and poor contact groups according to the TP level for analysis. ResultsThe TP group had a significantly shorter procedural time (16.2 ± 6.9 min vs. 19.9 ± 10.0 min, p = 0.033), shorter ablation time (334.6 ± 166.9 s vs. 391.3 ± 195.7 s, p = 0.049), and fewer mean numbers of radiofrequency catheter ablation (RFCA) deliveries (6.2 ± 3.2 vs. 7.6 ± 5.2, p = 0.047) than the non-TP group. The achieved average percentage of TP >3 g was significantly higher in the good-contact group (97.94% vs. 15.48%, p < 0.001). The median impedance decreases during RFCA in the good contact group and poor contact group were 4.10 (0.30–6.88) Ω and 2.60 (−0.05–4.98) Ω at 10 s, 4.45 (0.58–8.25) Ω and 2.88 (0.23–5.70) Ω at 20 s, and 4.67 (1.95–9.08) Ω and 2.97 (−0.26–6.33) Ω at 30 s, respectively (p < 0.05 for comparisons between categories). All patients achieved acute success, and no complications were observed. Two patients in the TP group and one patient in the non-TP group experienced recurrence during follow-up. ConclusionTP-technology guided ablation of SVT is feasible, efficient, and safe.

Shortened fluoroscopy duration and reduced use of contrast dye in cryoballoon-based pulmonary vein isolation procedures using KODEX-EPD’s novel occlusion tool

Abstract Funding Acknowledgements Type of funding sources: Private company. Main funding source(s): Study grant by EPD Solutions, Philips, Netherlands Background The occlusion tool was recently introduced for KODEX-EPD which is a novel dielectric high-resolution cardiac imaging system. The occlusion tool provides information about level of pulmonary vein occlusion by the cryoballoon (CB) in CB-based pulmonary vein isolation (PVI) ablation procedures for atrial fibrillation (AF). Purpose Assess effects of the introduction of the occlusion tool on procedural parameters during CB-PVI such as feasibility, acute efficacy and periprocedural safety of KODEX-EPD in different software versions. Methods and Results 173 consecutive patients (60/173 (35%) paroxysmal AF, 64±12 years, 66/173 (38%) female) underwent CB-PVI with EPD imaging between 08/2019 and 10/2021. 38/173 (22%) of all patients were treated using software version 1.4.6, 33/173 (19%) patients with version 1.4.6a, 41/173 (24%) patients with version 1.4.7 and 61/173 (35%) patients with the latest version 1.4.8. Acute PVI was achieved in all patients. No major periprocedural complications were documented. Software version showed significant effects on procedure duration, fluoroscopy duration and dose area product in ANOVA testing (Figure 1A-C). The largest effect in post-hoc testing was observed for fluoroscopy duration (Figure 1B). Tobit regressions were fitted to model effects of software version on the censored variable contrast volume. All software versions predicted used contrast volume (p&amp;lt;0.00748, Figure 1D). Modelling only effects of procedure date on contrast volume was less accurate than for software version (r²=0.057, p for procedure date = 0.0031) and also a Likelihood-Ratio-Test between different regression models underlined significant effects of software version (p&amp;lt;0.0001). Conclusion CB-based PVI in combination with its PV-occlusion tool is feasible and safe. The present data strongly suggests a steady positive development of the novel wide-band dielectric imaging and mapping system towards a fluoroscopy- and dye-reduced CB-based AF-ablation. Software versions were introduced sequentially. Therefore time (procedure date) needs to be considered as the most relevant confounder of the described results (e.g. due to a learning curve using the system). However, differentiated statistical testing could show that the results are mainly explained by software version and only much weaker by procedure date.

Optimizing catheter ablation of atrial fibrillation by a novel wide-band dielectric imaging system: first experience on real-time wall thickness measurement

Abstract Funding Acknowledgements Type of funding sources: None. Background Conventional mapping systems do not provide wall-thickness data, which is, however, known to be a determinant of radiofrequency ablation lesion transmurality. KODEX-EPD is a novel open-platform system, which uses dielectric tissue properties to provide real-time, high-resolution cardiac images, tissue characteristics and wall-thickness measurement to guide ablation procedures. Aim The aim of this case series was to report on our first experiences with KODEX-EPD regarding estimation of myocardial wall-thickness during catheter ablation of atrial fibrillation (AF). Methods We retrospectively analyzed consecutive patients undergoing radiofrequency AF-ablation in combination with KODEX-EPD. A high-resolution image from the left atrium (LA) and the pulmonary veins (PV) was obtained prior to ablation using a spiral mapping catheter in conjunction with KODEX-EPD. Wall-viewer points were collected within the LA, the PVs and the left atrial appendage (LAA) using a standard radiofrequency non-contact force ablation catheter and analyzed for wall-thickness applying the latest KODEX-EPD software version (1.5.0, not yet commercially released). Wall-viewer points were divided into a total of 10 segments (PV ostia, anterior wall, posterior wall, LA roof, LA floor, LAA and PV carina, details see Figure 1) in order to characterize wall-thickness in respective areas. Results A total of 570 wall-viewer points in 5 patients were analyzed. Most of the wall-viewer points were collected at the PV ostia as well as along the posterior and anterior wall (449/570, 79%). Actual myocardial atrial thickness ranged from 1.6 to 3.9 mm. Thickest myocardial LA-tissue was measured at the anterior wall (median 3.1 mm) and thinnest at the LA-roof (median 2.2 mm). Figure 2 gives a detailed distribution of wall-thickness measurements at different sites in the LA and PVs. Conclusion Atrial wall thickness can be estimated in patients during AF ablation procedures using dielectric tissue properties. Further evaluation and validation of the method are needed to study its reliability and utility for clinical practice.

PO-624-06 THE DIELECTRIC IMAGING SYSTEM IS SUPERIOR TO FLUOROSCOPY IN PREVENTING ATRIAL FIBRILLATION RECURRENCE AFTER CRYOABLATION

Dielectric imaging system allows a better visualization of pulmonary veins anatomy and occlusion assessment without dye use. Outcome data is still limited for this imaging system. We aim to analyze short-term atrial fibrillation (AF) recurrence outcomes when using dielectric imaging system mapping during cryoablation procedures. We retrospectively analyzed 32 patients who underwent cryoablation procedure in a single institution. Of those, 19 procedures were performed using dielectric imaging system while 13 procedures were performed using fluoroscopy (control group). Short-term 3-month recurrence outcomes were collected for all patients. Both groups were comparable in terms of sex (47% vs 38% males, p=0.62), age (61 vs 67 years, p=0.10), congestive heart failure (p=0.33), diabetes mellitus (p=0.31), history of stroke (p=0.79), history of coronary artery disease (p=0.46), hyperlipidemic profile (p=0.06). However, hypertension was more frequent in the control group than the dielectric imaging system group (p=0.03). On 3-month follow-up, 2 patients in the dielectric imaging system group had AF recurrence post-ablation, while 6 patients had AF recurrence in the control group. There was significant difference in AF recurrence rates between both groups (10% in the dielectric imaging system group vs 54% in the control group, p=0.007). Dielectric imaging system is superior to fluoroscopy during cryoablation procedure in preventing AF recurrence. Long-term larger prospective studies are needed to confirm the efficacy of the dielectric imaging system.

Intermittent-contact local dielectric spectroscopy of nanostructured interfaces

Local dielectric spectroscopy (LDS) is a scanning probe method, based on dynamic-mode atomic force microscopy (AFM), to discriminate dielectric properties at surfaces with nanometer-scale lateral resolution. Until now a sub-10 nm resolution for LDS has not been documented, that would give access to the length scale of fundamental physical phenomena such as the cooperativity length related to structural arrest in glass formers (2–3 nm). In this work, LDS performed by a peculiar variant of intermittent-contact mode of AFM, named constant-excitation frequency modulation, was introduced and extensively explored in order to assess its best resolution capability. Dependence of resolution and contrast of dielectric imaging and spectroscopy on operation parameters like probe oscillation amplitude and free amplitude, the resulting frequency shift, and probe/surface distance-regulation feedback gain, were explored. By using thin films of a diblock copolymer of polystyrene (PS) and polymethylmethacrylate (PMMA), exhibiting phase separation on the nanometer scale, lateral resolution of at least 3 nm was demonstrated in both dielectric imaging and localized spectroscopy, by operating with optimized parameters. The interface within lamellar PS/PMMA was mapped, with a best width in the range between 1 and 3 nm. Changes of characteristic time of the secondary (β) relaxation process of PMMA could be tracked across the interface with PS.

Unique Ligand Exchange Dynamics of Metal–Organic Polyhedra for Vitrimer-like Gas Separation Membranes

Unique Ligand Exchange Dynamics of Metal–Organic Polyhedra for Vitrimer-like Gas Separation Membranes