Conductive Patterns Research Articles

단위 셀 크기에 따른 금속 픽셀 기반 메타표면 흡수체의 대역폭 분석

The absorption bandwidth of a metasurface absorber can be adjusted by varying the thickness of the substrate, shape of the conductive pattern attached on top of the substrate, or conductivity of the pattern. In this study, the bandwidth of a pixelated metallic metasurface absorber was analyzed with respect to its unit cell size. The genetic algorithm (GA) was used to determine the best combination of the metallic pixels among 16 × 16 square pixels for each unit cell size. The size of the unit cell was adjusted around the 1/2 wavelength, which guarantees the suppression of the grating lobe for the normal-incidence condition. Based on full-wave simulation results, the −10 dB reflectance bandwidth was expanded as the size of the unit cell was increased from 3/8 to 3/4 wavelength with an interval of 1/8 wavelength at the center frequency of 5.8 GHz. The results demonstrate that the absorption bandwidth of the metasurface absorber is expanded by increasing the size of the unit cell around the 1/2 wavelength.

Fabrication of a Conductive Pattern on a Photo-Polymerized Structure Using Direct Laser Sintering

Three-dimensional (3D)-printed electronic technology is considered to have great potential as it can be utilized to make electronic products with complex 3D shapes. In this study, based on a 3D printer with single UV laser equipment, we continuously performed photo-polymerization (PP) and selective metal powder sintering to fabricate a conductive pattern. For this, 3D structures were printed at a low energy using a 355 nm DPSS laser with a galvanometer scanner, which are widely used in PP-type 3D printing, and then the selective sintering of metal powders was performed with a high energy. In order to obtain a high-conductivity pattern by laser sintering, a circuit pattern that could actually be operated was fabricated by experimenting with various condition changes from mixing the metal composite resin to the laser process. As a result, it was found that the optimal result was to irradiate a 0.8 W UV laser with a beam spot size of 50 µm to 50 vol% aluminum composite resin. At this time, an optimal conductive pattern with a resistance of 0.33 Ω∙cm−1 was obtained by setting the pulse repetition rate, scan path interval, and scanning speed to 90 kHz, 10 μm, and 50 mm/s, respectively. This suggested process may be of great help in the manufacturing of practical 3D sensors or functional products in the future.

Beeswax multifunctional composites with thermal-healing capability and recyclability

Natural beeswax reinforced with conductive nanofillers allows solvent-free processing and presents remarkable functional response as piezoresistive and thermoresistive sensors with thermal healing capability. The low melting temperature of the composites, around 60 °C, allows additive manufacturing of conductive patterns with a high electrical conductivity of 50 S/m. Further, the graphene/beeswax composites show suitable deformation and temperature sensing characteristics based on the piezoresistive and thermoresistive sensitivities, around GF≈9 and S≈ 120 %/°C, respectively. Natural beeswax is a food and drug administration approved substance, and all graphene/beeswax composites present no cytotoxic behavior, demonstrating their potential use for biomedical applications.Proofs-of-concept demonstrate the conductive and thermal-healing properties of the screen-printed sensors developed both on paper and Kapton substrates, proving the applicability and multifunctionality of the developed materials. Finally, the multifunctional composites can be recycled and reused without losing their electrical and functional performances.

An extended theory of vacancy formation and its application to ionic conduction in the intrinsic and extrinsic regions

ABSTRACT The theory of the vacancy formation in crystals has been extended by generalising the vacancy formation energy that depends on the number of vacancies resulting from thermal activation. This extension enables to describe the freezing of defect concentrations at lower temperature, while the derived vacancy concentration reduces to the Boltzmann–Arrhenius law at higher temperature. The implications of the low-temperature patterns and its relevance to non-equilibrium process in the defect concentrations have been also touched upon. In addition, based on the approach explored, we further construct a model for the ionic conductivity in the intrinsic and extrinsic regions, which is formulated by focusing on the relation between the number concentration and the mobility of ionic charge carriers. A theoretical background to the continuity (knee) across which the both ionic conductivity patterns are smoothly connected is corroborated by the present work.

Stability Analysis of Binary Casson Nanofluid Convection With Viscosity and Conductivity Variations Using Darcy–Brinkman Model

Abstract The onset of binary/double-diffusive convection with conductivity and viscosity variations has been investigated for Casson nanofluids using Darcy–Brinkman model. Nanoparticle conductivity and viscosity are used as linear functions of volume fraction. The normal mode approach, linearized stability theory, and one-term Galerkin method are used to obtain the expressions of Darcy–Rayleigh number for stationary and oscillatory convection. Different base-fluids (water, blood, honey) for different porous phases (glass, limestone, sand) have been examined numerically using the software mathematica (version 12.0). When Darcy parameter, conductivity, and viscosity variation parameters are combined, the layer's stability is significantly enhanced. The top-heavy layer of fluid instability state is shown to be dominated by stationary mode. It is observed that non-Newtonian Casson parameter and solute Lewis number destabilize the system while porosity parameter, Darcy number, and solute Rayleigh number postpone the same. Interestingly, thermal capacity ratio, conductivity, and viscosity parameters have stabilizing effects. A comparison of stability patterns of Newtonian and non-Newtonian nanofluids is carried out numerically by taking different base fluids like water (Newtonian fluid), blood, and honey (non-Newtonian Casson fluids). The system is found to be more stable for non-Newtonian fluids. It is observed that conductivity variation pattern for different porous media is: glass < limestone < sand for all the base fluids. As far as base fluids are concerned, they follow the conductivity pattern as water < honey < blood for different porous phases.

Left bundle branch pacing is superior in preserving ventricular mechanical synchrony and cardiac function than right ventricular pacing: a two-center experience

Abstract Background Left bundle branch pacing (LBBP) has emerged as a novel pacing modality. Although it has been proved to maintain electrical synchrony better than right ventricular pacing (RVP), little is known about the impact on mechanical synchrony. This study investigates if LBBP preserves mechanical synchrony and cardiac function better compared to conventional (CRVP) and leadless (LRVP) RVP. Methods Sixty-five patients with pacing indication for bradycardia were prospectively enrolled: Twenty-two were treated with LBBP, 23 with CRVP and 20 with LRVP. All patients underwent echocardiography before and after implantation and at one-year follow-up. Left ventricular (LV) volumes, ejection fraction (EF) and global longitudinal strain (GLS) were measured. Regional septal (SW) and lateral wall work (LW) was calculated as the average from the respective basal and mid-ventricular segments in the apical four-chamber and three-chamber view. The lateral-septal work difference (LSWD) was used as a measure of mechanical dyssynchrony. Results At baseline, the QRS duration and LSWD were similar in all three groups. During follow-up, the QRS duration increased least in LBBP compared to CRVP and LRVP (+28.1±18.3ms vs +58.2±31.4 and 47.1±26.1ms, both P<0.01). SW was markedly decreased in CRVP and LRVP while LW work remained unchanged, resulting in a large LSWD compared to LBBP (1308.4±732.9 mmHg*% and 1451.3±606.1 mmHg*% vs. 286.0±479.9mmHg*%, both P<0.001). During one year follow-up, LVEF and LV GLS decreased more in CRVP compared to LBBP (both P<0.05). Conclusion LBBP causes less LV dyssynchrony than CRVP and LRVP as it preserves a more physiologic conduction pattern. With this, LBBP appears to preserve LV function better than CRVP. CRVP and LRVP did not differ in mechanical dyssynchrony or LV remodelling. Funding Acknowledgement Type of funding sources: None.

Hopping Mechanism and Impedance Properties of Mg Doped NBT-KBT Solid Solution near Ambient Temperature

Solid state reaction route has been utilized to synthesize Na0.42K0.08Bi0.50Mg0.05Ti0.95O3−δ solid solution. Impedance plots are used to examine electrical attributes as a function of frequency (100 Hz –1 MHz) and temperature (10 °C–50 °C). The existence of bulk and grain boundary contributions in the impedance has been revealed by the nature of Nyquist plots. The presence of conductivity relaxation in the sample is indicated by the merging of normalized plots of modulus () profile. The ac conductivity follows Jonscher’s Power law, and suggested the correlated barrier hopping (CBH) conduction mechanism, whereas, the dc conductivity is found to be Arrhenius dependent. The activation energies computed from the conductivity and relaxation patterns are nearly identical which are 1.30 eV and 1.39 eV respectively.

Electrohydrodynamic Direct‐Writing Fabrication of Microstructure‐Enhanced Microelectrode Arrays for Customized and Curved Physiological Electronics

AbstractMetal‐based patterned conductors have a key role in flexible and curved micro/nanodevices. However, the fabrication of micro/nanoscale metal‐based electrodes with excellent electrical conductivities and well‐organized flexible/curved polymeric substrates remains a major challenge associated with a posttreatment. In this study, a maskless and direct‐writing method of electrohydrodynamic jet (e‐jet) printing combined with the conventional wet etching process is developed for fabrication of microscale conductive features of microstructure‐enhanced patterned electrodes without high‐temperature treatment. Customized metal‐patterned electrodes and various metal‐patterned electrode arrays are fabricated on a flexible/curved polyethylene terephthalate substrate. In addition, ultraviolet‐curable hierarchical micro/nanostructures can be fabricated by stable cone‐jet and electrospray modes. The results of electrocardiography (ECG) and electromyography signal measurements show that the added microstructures can increase the contact between the metal microelectrodes and skin surface, which yield lower disturbance and baseline drift and enable a stable ECG signal acquisition. Overall, e‐jet printing is a promising mask‐free approach for fabrication of conductive metal patterns for flexible and stretchable devices.

Polyvinylidene fluoride/polysulfone/air plasma defected hexagonal boron nitride emerging nano blends for electrostatic dissipation

AbstractIn the present era electrostatic dissipation (ESD) property is crucial for packaged electronic device to protect from humidity over long duration. It was important to control the ESD for better integrated packaged electronic gadgets. Polymer blends and composites were modified with nano fillers as a promising area for ESD applications. In the present investigation, polyvinylidene fluoride (PVDF)/polysulfone (PSF) was modified by untreated (UT) and air plasma treated (PT) hexagonal boron nitride (h‐BN) by solution dispersion method. Spherulitic morphology of nano blends was foreseen through scanning electron microscopy. Surface topography was investigated by atomic force microscopy. Surface roughness was decreased due to plasma exposure. Phonon vibrations and Raman active mode of nano blends were confirmed by Raman spectroscopy mutually supporting ESD phenomenon. Increased electrical conductivity and semicircular impedance pattern of modified blends reveals an excellent ESD property disclosed by impedance spectroscopy. Moderate increased surface energy and decreased relative contact angle of modified blends may be due to the incorporation of polar groups during plasma exposure was confirmed by surface goniometer. Mechanical properties of nano blends were evaluated by universal testing machine. Increased 10–27% tensile strength and 34–55% Young's modulus of plasma treated admix composition. Softness of polymer nano blends was increased (20%) due to excellent interaction of filler and polymer host system were tested by Shore “A” durometer. Increased glass transition temperature (Tg = 16 and 30°C as function of treatment time) in view of thermal stability of modified nano blends were analyzed by thermogravimetric technique. Hence the PT h‐BN dispersed PVDF/PSF emerging polymer nano blends would be a choice for the new development for electrostatic dissipation applications.

Textile-Based Wearable Sensor for Skin Hydration Monitoring.

This research describes a wearable skin hydration sensor based on cotton textile to determine the state of hydration within the skin via impedance analysis. The sensor structure comprises a textile substrate, thermoplastic over-layer, conductive patterns, and encapsulant, designed for stable and reliable monitoring of the skin’s impedance change in relation to hydration level. The porcine skin with different hydration levels was prepared as a model system of the skin, and the textile-based sensor carefully investigated the porcine skin samples’ impedance characteristics. The impedance study reveals that (1) the total impedance of skin decreases as its hydration level increases, and (2) the impedance of the stratum corneum and epidermis layers are more dominantly affected by the hydration level of the skin than the dermis layer. Even after repetitive bending cycles, the impedance data of skin measured by the sensor exhibit a reliable dependence on the skin hydration level, which validates the flexibility and durability of the sensor. Finally, it is shown that the textile-based skin hydration sensor can detect various body parts’ different hydration levels of human skin while maintaining a stable conformal contact with the skin. The resulting data are well-matched with the readings from a commercial skin hydration sensor.

The H+ ion transport study in polymer blends incorporated with ammonium nitrate: XRD, FTIR, and electrical characteristics

The present study gained insights into H+ ion transport through non-destructive techniques. The XRD outcome reveals that poly(2-ethyl-2-oxazoline) (POZ) reduced the crystalline phase of chitosan (CS) effectively. Films of ion-conducting polymer blend electrolytes were created from CS:POZ complexed with ammonium nitrate (NH4NO3) as an H+ supplier by using the solution casting method. X-ray diffraction was used to study the structural alterations that occurred. The degrees of crystallinity were estimated from the deconvoluted XRD pattern. Measurement of electrical impedance was carried out for the electrolytes. From FTIR measurement, free ion and ion pair values were calculated. Several ion transport parameters (ITP), such as number density (n), ionic mobility (μ), and diffusion coefficient (D), were determined. It was found that the maximum conductivity was 3.87 × 10−6 S cm−1 at 30 percent NH4NO3. The DC conductivity pattern changes linearly with temperature. Dielectric and electric modulus were studied in detail. It was discovered that the loss tangent peak transferred to a upper side of frequency when the salt concentration was increased. Long-range conductivity relaxation was seen in the Mi spectra. The lack of a full semicircle arc on the Argand figure suggested non-Debye ion dynamics. The observed AC conductivity (σac) spectra showed three different zones. In the high-frequency range, the σac value follows a power law (σac=Aωs).

Enhanced Assembly of Ag Nanoparticles for Surface-Independent Fabrication of Conductive Patterns

Polymer stamping is a reliable and cost-effective method for producing charged patterned surfaces. However, charge stability is limited, and they discharge steadily while immersed in polar solvents. Here, we applied polyelectrolytes as the stamping medium to increase this stability. Charged line patterns were fabricated by pressing a polydimethylsiloxane (PDMS) stamp covered with a polyethylenimine (PEI) solution against silicon, glass, or polystyrene. Then, the substrate was immersed in a solution of oppositely charged silver nanoparticles. Finally, silver crystallization on the deposited nanoparticle agglomerates was performed to homogenize the conductive surface. Fabricated structures were characterized by conductive AFM, SEM, and electrical measurements. Simulations of the electric field above the pattern and electrostatic deposition of nanoparticles were performed. The presented method allows for the production of high-resolution microstructures composed of parallel 45 mm paths with a width of 10 μm and a thickness below 100 nm. A conductivity of 104 S/m is high enough to keep a commercial LED on.

Atrial fibrillation mechanisms before and after pulmonary vein isolation characterized by noncontact charge density mapping.

The interaction of the pulmonary vein (PV) and putative nonpulmonary triggers of atrial fibrillation (AF) remains unclear and has yet to translate into patient-tailored ablation strategies. The purpose of this study was to use noncontact mapping to detail the global conduction patterns in paroxysmal and persistent AF and how they are modified during PV ablation. Forty patients during AF ablation underwent mapping using a noncontact catheter (AcQMap, Acutus Medical, Inc., Carlsbad, CA) before and after PV isolation (PVI). Propagation history maps were analyzed postprocedure for each patient to categorize conduction patterns into focal, organized reentrant, and disorganized patterns (F-Patterns, O-Patterns, and D-Patterns, respectively). Activation patterns identified by using a noncontact mapping system can be subclassified from 3 main patterns into subtypes (macroreentrant and localized reentrant [MR and LR] subtypes and disorganized 1 and disorganized 2 [D1 and D2] subtypes). Persistent AF demonstrated more D-Patterns and less O-Patterns and F-Patterns than did paroxysmal AF. In addition, patients with PAF inducible after PVI demonstrated a higher region number and higher prevalence of MR subtypes than did those noninducible. PVs remained the critical region and included almost one-third of all patterns across any AF types. PVI was effective to eliminate PV-related functional phenotypes and affected recurrence with other patterns. Activation patterns identified using AcQMap can be classified into 3 main patterns (F-Patterns, O-Patterns, and D-Patterns) as well as subtypes (MR and LR subtypes and D1 and D2 subtypes). PerAF was different from PAF in demonstrating a higher region number and higher prevalence of D-Patterns but a lower region number and lower prevalence of O-Patterns and F-Patterns.

Fabrication of a Multilayer X-Band Band-Pass Metasurface Using Liquid Metal

Fabrication of a physically flexible multi-layer metasurface composed of gallium-based liquid metal encapsulated in polydimethylsiloxane (PDMS) is reported. The second-order bandpass frequency selective surface (FSS) operating in the X-band is comprised of two modified Jerusalem cross resonator layers separated by an aperture layer. The multi-layer spatial filter has a total thickness of 4.81 mm ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{0}$ </tex-math></inline-formula> /7.5). An inverse image mold of the FSS layer patterns is fabricated in silicon, and FSS patterned PDMS is replicated from the silicon mold. The FSS patterned PDMS is spray coated with liquid metal to fabricate a massive array of discrete conductor patterns in PDMS and subsequent encapsulation by an additional layer of PDMS. Multiple versions of the m <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> n metasurfaces have been fabricated and have been repeatedly tested for their bendability, stretchability, twistability, and foldability. The fabricated metasurface in a waveguide environment demonstrated a band-pass center frequency at 8.33 GHz which agreed well with the simulated frequency at 8.31 GHz.

New insights into the mechanisms of fast and slow conduction in the atrioventricular node

Cardiac pathologists and electrophysiologists have studied the atrioventricular (AV) node since 1906, when Tawara 1 Tawara S. Das Reitzleitungssystem des Saugetierherzens: Eine anatomisch-histologische Studie uber das Atrioventrikularbundel und die Purkinjeschen Faden. Gustav Fischer, Jena, Germany1906: 135-136 Google Scholar described its inferior extensions in the human heart. One century later, this important cardiac structure still carries the reputation of a profound enigma, invoked as the riddle of Sphinx, by means of its electrophysiological properties during both normal conduction and reentrant tachycardia. 2 Katritsis D.G. The human atrioventricular node: oedipus and the riddle of the Sphinx. Arrhythm Electrophysiol Rev. 2020; 9: 52-53 Crossref PubMed Scopus (0) Google Scholar In recent years, considerable evidence has accrued pertaining to its anatomic structure, 3 Inoue S. Becker A.E. Posterior extensions of the human compact atrioventricular node: a neglected anatomic feature of potential clinical significance. Circulation. 1998; 97: 188-193 Crossref PubMed Scopus (271) Google Scholar , 4 Hikspoors J. Macias Y. Tretter J.T. et al. Miniseries 1–part I: the development of the atrioventricular conduction axis. Europace. 2022; 24: 432-442 Crossref PubMed Scopus (1) Google Scholar , 5 Macias Y. de Almeida M.C. Tretter J.T. et al. Miniseries 1–part II: the compara-tive anatomy of the atrioventricular conduction axis. Europace. 2022; 24: 443-454 Crossref PubMed Scopus (3) Google Scholar , 6 Anderson R.H. Sanchez-Quintana D. Mori S. Cabrera J.A. Back Sternick E. Re-evaluation of the structure of the atrioventricular node and its connections with the atrium. Europace. 2020; 22: 821-830 Crossref PubMed Scopus (32) Google Scholar along with the electrophysiological properties, which have allowed identification of the so-called fast and slow pathways involved in atrioventricular nodal reentrant tachycardia (AVNRT). 7 Katritsis D.G. Josephson M.E. Classification, electrophysiological features and therapy of atrioventricular nodal reentrant tachycardia. Arrhythm Electrophysiol Rev. 2016; 5: 130-135 Crossref PubMed Scopus (29) Google Scholar , 8 Katritsis D.G. A unified theory for the circuit of atrioventricular nodal re-entrant tachycardia. Europace. 2020; 22: 1763-1767 Crossref PubMed Scopus (7) Google Scholar , 9 Katritsis D.G. Calkins H. Anderson R.H. The specialized atrioventricular ring tissues participate in the circuit of atrioventricular nodal reentrant tachycardia. J Am Heart Assoc. 2021; 10e022811 Crossref Scopus (0) Google Scholar But still the nature of these patterns of conduction in the context of sinus rhythm, as opposed to those observed during tachycardia, remains obscure. In the great Sophoclean tragedy, in light of its insurmountable difficulty, the denouement of the riddle of Sphinx by mortal Oedipus was initially perceived by the Athenians as a form of hubris against the gods by a human. 10 Sophocles. Oedipus Tyrannus. 429 BC. Google Scholar We believe that the accumulation of recent anatomic and electrophysiological evidence now enables us to provide the rationale for solving the nodal riddle without committing scientific hubris.

Optimizing the Morphology, Structure and Optoelectronic Properties of Aluminum Doped Zinc Oxide Thin Films Developed via Wet Chemical Synthesis

Transparent conducting oxides (TCOs) are wide band gap semiconductors having found their use in optoelectronics, flexible electronics, flat panel displays, electrochromic windows, transparent heater windows, and many more. Aluminum (Al) doped zinc oxide (AZO) is an important TCO material which is being widely investigated for such applications. Its optoelectronic properties can be tuned by adjusting the Al content. In this work we study the variation patterns of the electrical conductivity and the optical transparency of AZO thin films with altering the Al content between 0 and 8 at%. The AZO thin films were prepared by wet chemical synthesis from its stabilized sol of zinc acetate dihydrate and aluminum nitrate nonahydrate dissolved in an ethanol and methanol mix. The morphological, electrical, and optical characteristics of these films were explored employing optical microscopy, Hall effect measurements, and UV-Vis-NIR spectrophotometry, respectively. We found out that annealing induces cracks into the AZO thin films and can severely degrade its electrical conductivity. Therefore, it’s imperative to control the Al content as well as the film morphology and structure. Before studying the effects of the Al content, the cracks were mitigated by optimizing the deposition and annealing conditions. The films were spin coated from its sol at 3000 RPM for 30 seconds. The films were dried at 100 °C and were subsequently annealed at 450°C. Since annealing induced cracks, therefore three coats were applied and annealed each time to mitigate the number of transverse cracks across the thickness of the film. The crack minimization was also confirmed by the enhancement in electrical conductivity. For the uniform crack-free AZO films, the Al doping was found to significantly modify the electronic behavior of the films. We expect an initial increase in the conductivity up to around 2 at% Al doping beyond which a decrease in conductivity is expected due to Al2O3 formation.

Characteristics of Methyl Cellulose Based Solid Polymer Electrolyte Inserted with Potassium Thiocyanate as K+ Cation Provider: Structural and Electrical Studies

The attention to a stable and ionic conductive electrolyte is driven by the limitations of liquid electrolytes, particularly evaporation and leakage, which restrain their widespread use for electrochemical device applications. Solid polymer electrolyte (SPE) is considered to be a potential alternative since it possesses high safety compared to its counterparts. However, it still suffers from low device efficiency due to an incomplete understanding of the mechanism of ion transport parameters. Here, we present a simple in situ solution casting method for the production of polymer-based electrolytes using abundantly available methylcellulose (MC) doped at different weight percentages of potassium thiocyanate (KSCN) salt. Fourier transform infrared (FTIR), and electrochemical impedance spectroscopy (EIS) methods were used to characterize the prepared samples. Based on EIS simulation and FTIR deconvolution associated with the SCN anion peak, various ion transport parameters were determined. The host MC medium and KSCN salt have a strong interaction, which was evident from both peak shifting and intensity alteration of FTIR spectra. From the EIS modeling, desired electric circuits correlated with ion movement and chain polarization were drawn. The highest ionic conductivity of 1.54 × 10−7 S cm−1 is determined from the fitted EIS curve for the film doped with 30 wt.% of KSCN salt. From the FTIR deconvoluted peak, free ions, ions in contact with one another, and ion aggregates were separated. The extracted ion transport parameters from the EIS method and FTIR spectra of the SCN anion band confirm that both increased carrier concentration and their mobility were crucial in improving the overall conductivity of the electrolyte. The dielectric investigations were further used to understand the conductivity of the films. High dielectric constants were observed at low frequencies for all MC:KSCN systems. The dispersion with a high dielectric constant in the low-frequency band is ascribed to the dielectric polarization. The wide shift of M″ peak towards the high frequency was evidenced by the MC-based electrolyte impregnated with 30 wt.% of KSCN salt, revealing the improved ionic movement assisted with chain segmental motion. The AC conductivity pattern was influenced by salt concentration.

Orthogonal Growth for Fabricating Hydrogel Sensors and Circuit Boards with In Situ Post‐Tunable Performance

AbstractConductive hydrogels generally possess dual network structures consisting of hydrophilic cross‐linked polymer frameworks and conductive paths. The post‐modification of their structures and performance for fabricating devices with 3D conductive patterns is challenging because of their covalently cross‐linked complex matrices. Here, an orthogonal‐growth strategy is described for modulating all‐aspects of conductive hydrogels, including size, pattern, conductivity, and conductive path. In this strategy, the matrices controlling samples’ size and the functional components modulating samples’ conductivity can be orthogonally varied by feeding corresponding nutrients. Using poly(hydroxyethyl acrylate)‐polyaniline organohydrogels (PHEA‐PANI) as an example, it is demonstrated that the samples can incorporate the hydroxyethyl acrylate monomer to expand (21.9‐fold in weight is shown) or integrate aniline into the conductive networks to tune conductivity (from 0 to 42.6 mS cm‐1) without changing the sample size. Moreover, the growth of PANI is spatially selective. Exploiting the selective modulation of various parameters through this method, strain sensors with post‐modulated sensing performance and 3D hydrogel circuit boards are fabricated.

A flexible tactile sensor based on piezoresistive thin film for 3D force detection.

This paper presents a flexible tactile sensor with a compact structure based on a piezoresistive thin film and an elastomer for detecting three-dimensional (3D) force. The film contains four independent sensing cells, which were made using a type of piezoresistive ink and a specific pectinate conductive circuit pattern based on the flexible substrate to decrease the coupling effect. The elastomer with a spherical surface is bonded to the surface of the film and transfers the force to the sensing array. A model of 3D force detection based on the proposed sensor was established, and a prototype was designed and developed. Static and dynamic experiments were carried out, and the results show that the range of the prototype is 0-50 N in the z-axis and 0-6 N in the x-axis and y-axis, which with good static and dynamic performance, especially a low coupling effect, validates the mechanism of the proposed sensor and indicates that it has good potential application in robotic grasping.

Design of proton conducting solid biopolymer blend electrolytes based on chitosan‐potato starch biopolymers: Deep approaches to structural and ion relaxation dynamics of H+ ion

AbstractThe need for flexible energy storage devices for advanced technologies has encouraged researchers to focus on environmental‐friendly biopolymers. In this work, chitosan (CS) and potato starch (PS) biopolymers are blended to prepare proton conducting solid electrolytes. Based on the X‐ray diffraction (XRD) inspection, the most amorphous blended film with the lowest crystallinity degree was selected to prepare polymer electrolytes. The variation in Fourier‐transform infrared spectroscopy (FTIR) bands were used to investigate the occurrence of interactions among the ammonium thiocyanate (NH4SCN) salt and CS:PS polymer blends. The experimental results of electrochemical impedance spectroscopy (EIS) were simulated with electrical equivalent circuit (EEC) modeling to determine the circuit elements. The highest value of S cm−1 was recorded for the sample included 40 wt.% of dopant salt. The dielectric analyses were helpful in separating the regions ascribed to electrode and molecular polarizations. The combination of circuit elements achieved from the EEC modeling and Koops phenomenological interpretation is used to understand the behavior of the loss tangent (tanδ) pattern. The AC conductivity pattern followed Jonscher's power law. The relaxation dynamics interrelated with ions is explained using electric modulus approaches. The peaks hidden in the dielectric loss () spectra, were manifested in the imaginary part of electric modulus () pattern. The ‐ patterns were used to shed light on the coupling between ionic motion and polymer chain dynamics.