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Cationic Complex Polymer Separator Confined Anionic [Zn(OH) <sub>4</sub> ] <sup>2‒</sup> Reduction for Stable Alkaline Batteries
ABSTRACT Unlike neutral aqueous batteries with cationic Zn 2+ as the charge carrier, alkaline batteries with anionic [Zn(OH) 4 ] 2‒ and OH ‒ are actually commercially feasible and thermodynamically stable thanks to their ability to suppress hydrogen evolution. Whereas commercial separators in alkaline batteries, without ion regulation capability, fail to suppress severe dendrite and passivation of anionic [Zn(OH) 4 ] 2‒ and accelerate ion transport of anionic OH ‒ . Herein, we tailor the coordination structures of alkali‐stable cationic complexes in polymer separators (CCPS) to construct anionic OH ‒ selective transfer channels. Synchrotron spectroscopic characterizations and theoretical calculations reveal that the low‐coordination cationic complexes expose more positive charge density, electrostatically attracting more negative charge from [Zn(OH) 4 ] 2‒ . In situ electrochemical digital holography technology and time‐of‐flight secondary ion mass spectrometry analyses further confirm the homogeneous [Zn(OH) 4 ] 2‒ distribution at the CCPS‐electrode interface, oriented Zn deposition, and impeded passivation. As a result, CCPS enables alkaline Zn||Cu cells to operate over 5500 cycles at 1 mA cm ‒2 with a high coulombic efficiency of 99.99%. Alkaline Ni–Zn batteries exhibit ultrastable cycling over 1000 cycles at 6 C and maintain 86.17% of their maximum capacity at 10 C. Our work may provide practical and effective separator strategies to accelerate the commercialization of alkaline batteries.
Low‐Dimensional Zero Thermal Expansion Enables Ultrastable Thermo‐Optics in YAl <sub>3</sub> (BO <sub>3</sub> ) <sub>4</sub> Single Crystal
ABSTRACT Zero‐thermal‐expansion (ZTE) materials are critical for stabilizing device performance under thermal fluctuations. Traditionally, achieving enhanced thermal stability has required three‐dimensional (3D) ZTE, a stringent condition that severely limits material availability. Here, we show that low‐dimensional ZTE can be realized in single crystals by orienting ubiquitous bond rotations along specific crystallographic axes in the framework structures, thus relaxing the strict requirements for 3D ZTE. This approach enables a two‐dimensional ZTE response, as demonstrated in a trigonal YAl 3 (BO 3 ) 4 (YAB) crystal, which exhibits an ultralow thermal expansion coefficient of −0.02(7) MK −1 within the ab plane from 83 to 180 K. The practical impact of this low‐dimensional ZTE is evidenced by the thermo‐optical performance of YAB crystal: within the ZTE temperature range, the thermo‐optical coefficient varies by only 0.03(2) × 10 −8 K −2 in the ZTE plane, approximately two orders of magnitude lower than those of conventional optical materials. This study establishes a new design strategy for functional ZTE materials and highlights the application potential of dimensionally confined ZTE effects in precision optical and electronic devices.
Localized Tuning Fields for 3D Hand Position in the Primary Motor Cortex and Premotor Cortex of Macaques
A central question in motor neuroscience is how the brain represents the state of the limbs to guide volitional movements. While the primate motor cortex is known to encode movement kinematics, such as velocity and direction, whether it also maintains a direct and explicit representation of hand position in 3D space remains debated. To address this, we recorded the activity of single neurons in the primary motor cortex (M1) and dorsal premotor cortex (PMd) of two male rhesus macaques performing a naturalistic, self-paced 3D reach-and-grasp task. We found significant populations of neurons in both M1 (36.2%) and PMd (21.3%) that are robustly tuned to the instantaneous 3D position of the hand. In these neurons, the tuning for hand position—characterized by localized, elongated fields—coexists with tunings for other kinematic variables, reflecting the principle of mixed selectivity. Critically, the spatial organization of these representations differs between the two areas: M1 fields are systematically oriented along cardinal axes and exhibit multi-scale spatial clustering, whereas PMd fields are more randomly organized. Furthermore, a small subset of these hand position-tuned cells is sufficient to decode the hand’s 3D trajectory with high fidelity. Our findings demonstrate that an explicit and functionally organized representation of 3D hand position is a fundamental component of primate motor cortex, complementing dynamic motor signals to support high-fidelity motor control. Significance Statement To guide skilled actions, the brain must track the hand's location. While the motor cortex is known for controlling movement commands, we reveal it also creates an explicit, highly organized 3D map of hand position. This neural representation is systematically structured, differing between primary and premotor areas. This discovery reshapes our understanding of motor control, showing the brain merges spatial information (“where”) with motor commands (“how”) of the hand in the same areas. These insights are crucial for creating more effective brain-computer interfaces for individuals with paralysis.
Anterior cingulate cortex projections to the amygdala in primates: topographic and layer-specific organization underlying emotion and mood regulation
Emotion and mood regulation critically depends on interactions between the anterior cingulate cortex (ACC) and the amygdala. However, the detailed architecture of ACC projections to their major targets, the basal (BA) and accessory (AcBA) basal nuclei of the amygdala, remains unclear. To address this issue, a combined retrograde and anterograde tracing with viral vectors were performed in macaques of either sex to map the projection patterns from the pregenual (pgACC), subgenual (sgACC), and dorsal (dACC) subareas. Data revealed that ACC neurons projecting to the BA arose predominantly from the superficial layers (II/III) of all subareas and the deep layers (V/VI) of the sgACC, whereas ACC neurons projecting to the AcBA originated mainly in the deep layers of the sgACC and dACC. The present study defines the topographic and layer-specific organization of ACC–amygdala connectivity in primates and subserves to provide an anatomical basis for future causal and translational approaches, such as targeted interventions against ACC-related mood disorders. Significance Statement Emotion and mood regulation critically depends on interactions between the anterior cingulate cortex (ACC) and the amygdala, and their dysfunctions have been implicated in mood disorders such as depression. However, the detailed organization of primate ACC–amygdala circuitry remains to be fully understood. Notably, the existence of projections from the pregenual ACC (pgACC) to the basal nucleus of the amygdala (BA) has been controversial. Using viral vector-based neural tracings in macaques, we have identified a distinct pgACC–BA pathway and shown that this pathway arises predominantly from the superficial layers of the cortex. Such unexpected laminar origin, atypical for cortico–subcortical projections, reveals a previously unrecognized circuit architecture and challenges prevailing models of cortico–amygdala linkage involved in mood disorders.
High current ultrawide bandgap AlGaN pin diodes with low on-resistance and UVC emission
We report ultrawide-bandgap AlGaN pin diodes with high forward current density and deep-ultraviolet (DUV) electroluminescence signaling efficient carrier injection. The devices incorporate a 100 nm unintentionally doped intrinsic layer between polarization-doped n- and p-type regions, grown by plasma-assisted molecular beam epitaxy on bulk AlN substrates. Electrical characterization reveals current densities up to ∼28 kA/cm2, differential on-resistances below 1 mΩ cm2, ideality factors approaching 1.7, and a cutoff frequency fco = (2πRonCoff)−1 = 30.8 GHz. Capacitance–voltage measurements confirm a reduced junction capacitance relative to a pn diode without the i-layer, while electroluminescence shows ultraviolet emission at 248 nm from the polarization-doped regions. These results establish AlGaN pin diodes as a promising platform for high-speed, high-voltage, and DUV optoelectronic devices, offering a scalable approach to next-generation ultrawide-bandgap electronics and photonics.
Molecular dynamics study of ferroelectric switching mechanisms in monodomain and 180° domain walls of BaTiO3 and PbTiO3
Understanding the intrinsic switching mechanisms is essential for controlling polarization domains and enabling their integration into next-generation nanoelectronic devices. In this study, we employ molecular dynamics (MD) simulations to investigate the electric field induced polarization switching behaviors of two representative ferroelectric materials, BaTiO3 and PbTiO3 single crystals, initialized with either monodomain configurations or 180° domain walls. By investigating both macroscopic switching dynamics and microscopic dipolar patterns, we identify distinct switching pathways governed by the initial domain structure and material-specific characteristics. Our results reveal that BaTiO3 exhibits a transition from Kolmogorov–Avrami–Ishibashi (KAI)-type switching to nucleation-limited switching (NLS) at intermediate fields when initialized with domain walls, from the NLS switching to homogeneous switching (HS) at high fields, regardless of the initial configuration. In contrast, PbTiO3 single crystals show a strong dependence on the initial domain state: Systems with pre-existing domain walls follow a KAI-to-HS transition, while monodomain systems follow an NLS-to-HS pathway. These differences are attributed to variations in activation fields associated with nucleation vs domain wall motion. Beyond macroscopic kinetics, our simulations demonstrate complex microscopic features. PbTiO3 exhibits polarization vortices and curved dipolar structures during switching, indicative of non-Ising type behavior. In comparison, BaTiO3 displays anisotropic domain growth and directionally biased anisotropic chain correlations. These results provide a comprehensive view of intrinsic switching mechanisms and offer insight into the design of ferroelectric materials with tailored switching characteristics for advanced nanoelectronic devices.
Physics-driven mechanisms governing the pharmacokinetics and immune fate of gold nanoparticles. I. An ADIE framework perspective
Gold nanoparticles’ (GNPs) clinical translation requires a mechanistic understanding of their pharmacokinetics at the nano–bio interface. Classical ADME (Absorption, Distribution, Metabolism, Elimination) models describe biodegradable materials but do not capture the behavior of inorganic nanomaterials. The in vivo fate of GNPs is governed not by metabolic biochemistry but by transport physics, interfacial energetics (thermodynamics), and corona-encoded biological recognition. This Perspective introduces the ADIE (Absorption, Distribution, Interaction, Elimination) framework, in which Interaction becomes the central determinant of nanoparticle fate. Distribution reflects convection and diffusion transport, while Brownian motion and thermodynamics drive protein corona (PC) formation. The composition of the corona determines which liver cell populations engage each particle, directing GNPs toward Kupffer cells, liver sinusoidal endothelial cells, or hepatocytes through receptor-based pathways. Interaction is defined as the combined processes of biotagging (adsorption of PC that assigns each particle a biological identity) and biorecognition (receptor-mediated engagement of that identity by immune and non-immune liver cells). Within ADIE, Interaction replaces Metabolism because GNPs undergo biotagging rather than biochemical transformation. Elimination depends on size and uptake route. Ultrasmall GNPs below 6 nm undergo renal filtration, whereas larger or non-stealth particles enter hepatic processing. Kupffer cell uptake results in immune sequestration; LSEC uptake leads to endothelial retention; hepatocyte uptake enables limited biliary elimination in which a small fraction of intact GNPs is transported to the canalicular membrane for fecal excretion. Thus, the liver functions primarily as a retention organ but also provides a minor excretory pathway. This physics-driven Perspective (Paper I) establishes the mechanistic foundations of ADIE and explains how nano–bio interactions govern GNP fate. The companion article (Paper II) extends these principles to broader pharmacokinetic implications for nanoparticle biodistribution, retention, clearance, and design.
Mechanisms of dislocation loops influencing damage evolution of single crystal copper under uniaxial and triaxial tension
Dislocation loops are typical irradiation defects that significantly influence the mechanical behavior of irradiated materials. In this work, molecular dynamics simulations are performed to investigate the influence mechanisms of dislocation loops on damage evolution of single crystal copper, with a focus on the effects of loading conditions (uniaxial and triaxial strain tension) and dislocation loop types (interstitial and vacancy loop). Under uniaxial strain tension, interstitial and vacancy loops exhibit distinct effects on initial plasticity but comparable effects on damage evolution. Vacancy loops induce plasticity earlier than interstitial loops, while interstitial loops exhibit faster plastic development once plasticity is activated, leading to comparable damage evolution at later stages. Under triaxial strain tension, voids nucleate directly at the sites of both dislocation loops. Vacancy loops induce void nucleation earlier than interstitial loops due to their pre-existing dislocation junctions, whereas the latter require dissociation to form such junctions before void nucleation. Additionally, the sensitivity of damage evolution to loop size depends on both loading conditions and loop types. These findings provide valuable insights into the irradiation defect-mediated damage behavior and offer mechanistic support for constructing theoretical models of irradiated materials under extreme conditions.
Rapid general electromagnetic analysis of metallic surfaces via conformal energy minimization
We recently found that the electromagnetic scattering problem can be solved efficiently using an approach that expresses the fields in terms of a set of orthonormal basis functions. In this paper, we apply computational conformal geometry with the conformal energy minimization (CEM) algorithm to make possible fast solution of finite-frequency electromagnetic problems involving arbitrarily shaped, simply connected planar metallic surfaces. The CEM algorithm enables the transformation of arbitrary simply connected surfaces into a disk, where orthogonal basis functions can be defined and electromagnetic analysis can be significantly simplified. We demonstrate the effectiveness and efficiency of our method by investigating the resonance characteristics of two planar metallic surfaces: a square plate and a four-petal plate with semicircular side features. Our method extracts the circuit parameters, resonance frequencies, and resonance field distributions within seconds, accelerating resonant frequency determination by three orders of magnitude over conventional finite-element methods (e.g., COMSOL). Moreover, it directly and efficiently reveals low-energy, doubly degenerate resonance modes. These findings provide an analytical approach for calculating electromagnetic fields on complex geometries, contributing to the development of high-performance electromagnetic devices.
Electrical properties of electrochemically energized n-GaN under reverse-bias conditions
Electrochemical energization of n-GaN was conducted under reverse-bias conditions as well as forward-bias conditions that were used in our previous studies for anodization, and electrical properties of energized n-GaN were examined. The surface composition and electrical properties of the energized n-GaN were evaluated by x-ray photoelectron spectroscopy (XPS) and temperature-dependent Hall-effect measurements, respectively. XPS analysis revealed that surface oxidation occurred even under reverse-bias conditions. Furthermore, while the electron concentration slightly increased under forward-bias conditions, it decreased by four to five orders of magnitude under reverse-bias conditions, suggesting significant electron trapping. These results clearly indicate that the effects of electrochemical energization on n-GaN differ significantly between forward- and reverse-bias conditions. Based on these findings, a surface conceptual illustration of n-GaN that explains these results is proposed.
Manipulating acoustic waves in wavevector domain by using nonlocal metasurfaces: Analog differentiation and extreme acoustic detection
Conventional acoustic metasurfaces have shown exceptional capability through spatial wavefront engineering, but the degrees of freedom in the wavevector domain remain to be unlocked. Here, we shift the manipulation paradigm from the spatial domain to the wavevector domain via nonlocal metasurfaces (NMSs). The proposed NMS consists of two sublayers of surface groove structures cascaded via a nonlocal channel, which enhances internal transverse energy flow. An inverse design framework integrating the genetic algorithm with numerical simulation is established for the NMS design. We find that the internal nonlocal energy flow dictates the wavevector-dependent transmissivity of NMSs. The nonlocal effect on the amplitude transmissivity results from the interaction between two sublayers, while the transmitted phase is dominated by the backward sublayer. Differentiations of 1st order on a Gaussian beam and a cylindrical wave are demonstrated and show agreement between theoretical and numerical results. Furthermore, we showcase the practical applications of NMSs in detecting deep subwavelength scatterers with diameters of 0.15 wavelengths, and isolating a weak source buried in a strong noise with a tenfold amplitude. Robustness analyses show that the transfer functions and detection and isolation effects of the proposed NMSs keep acceptably stable when thermoviscous loss, fabrication error, imperfect periodicity, structural defect, and background reverberation are considered. Our work elaborates the physical image of acoustic wavefront reshaping in the wavevector domain, paving the way for advanced applications in signal processing, imaging, and sensing and communication.
The effect of aging and charge variability on the detonation performance of a conventional plastic-bonded high explosive
Plastic-bonded explosives (PBXs) are pressed composites of energetic crystals (&gt;90 wt. %), polymeric binder, and an internal porosity structure (1–2 vol. %). The binder ensures material stability, while porosity promotes more reliable reaction initiation. These microstructural features critically influence the bulk mechanical and detonation performance properties of the high explosive (HE), yet the connection between microstructure and bulk behavior remains incompletely understood, complicating both manufacture and characterization. Aging of HE constituents under varying environmental conditions introduces additional uncertainty. For PBXs composed of cyclotetramethylene–tetranitramine (HMX), it is commonly assumed that detonation performance, specifically detonation velocity and energy release, are insensitive to microstructural details and do not vary significantly over time. This assumption simplifies constitutive modeling choices at the engineering scale. Here, we analyze four high-precision cylinder expansion tests of an HMX-based PBX varying in molding powder lot, pressing method, final pressed density, and pressing age. These data support hydrocode-based model calibrations of the explosive product equation of state, and these are used to quantify the effect of the described material variability on energy release characteristics. The results indicate that the detonation velocity increases with density and may also increase with age, though further experiments would be required for confirmation. No significant variation in energy delivery was observed across the tests.
Analytical calculation of field enhancement factor of 2D structure graphene film
Field emitters are one of the promising electron sources for vacuum electronic devices operating in mm-wave and terahertz frequencies, where emission performance is critically governed by the field enhancement factor. While extensive analytical models exist for one-dimensional emitters like carbon nanotubes and Spindt tip, the corresponding framework for a thin-film (like two-dimensional) emitter remains lacking. In this work, an analytical field enhancement factor is derived using the floating-sphere and image-charge approach, based on a vertically oriented graphene sheet inside a closely spaced diode configuration. The model explicitly incorporates emitter dimensions such as height, width, thickness, and anode–emitter spacing. The proposed expression is validated by comparison with previously reported experimental data on reduced graphene oxide film based emitters. Good agreement between the emission current predicted via the proposed approach, and experimentally obtained data are observed for ultra-thin films, whereas a deviation in predicted and experimentally obtained data for films with higher thickness is observed. This deviation rises with increasing thickness, highlighting the limitations of the two-dimensional approximation. The proposed approach provides a useful analytical tool to estimate the field enhancement of graphene sheet field emitters for miniaturized THz vacuum electron device applications.
Weakly nonlocal thermoelasticity of type II: Rayleigh waves in coated half-spaces
It is well known that Eringen’s nonlocal thermoelasticity theory using the nonlocal Fourier law of heat conduction and its modifications has been widely applied to harmonic plane wave problems. However, it has recently been proven that a significant class of these problems such as Rayleigh wave propagation in layered nonlocal thermoelastic half-spaces is ill-posed under this theory in the sense of yielding no solutions because the number of required boundary conditions exceeds the number of constants to be determined. Therefore, it is necessary to develop nonlocal thermoelasticity theories under which the number of required boundary conditions and the number of constants to be determined are the same for all harmonic plane wave problems. In this paper, we introduce such a theory, called the weakly nonlocal thermoelasticity theory of Green–Naghdi type II (without energy dissipation). Employing this theory, we investigate Rayleigh wave propagation in a nonlocal type II thermoelastic half-space coated with a nonlocal type II thermoelastic layer. Departing from previous methodologies, we establish the explicit transfer matrix for a layer and the explicit surface impedance matrix of a half-space in the framework of this new theory. These results allow us to obtain directly the explicit secular equation of Rayleigh waves, which is a 3 × 3 determinant equation, along with the explicit H/V ratio formula. Based on these analytical results, we numerically examine the effects of nonlocality and material parameters on Rayleigh wave characteristics, focusing on both phase velocity and displacement polarization.
Higher-winding phases in one-dimensional non-Hermitian topological superconductors
Non-Hermitian topological superconductors provide a setting in which point-gap topology, non-Hermitian skin effects, and Majorana zero modes are strongly intertwined. In this work, we adopt a coefficient-based approach for computing winding numbers and deriving analytical expressions for phase boundaries in one-dimensional non-Hermitian topological superconductors characterized by point-gap topology with Z invariants. We apply this approach to two non-Hermitian topological superconducting lattice models, with and without sublattice degrees of freedom, including longer-range hoppings, thereby accessing a much broader parameter space. These extensions generate higher-order polynomials and support phases with higher winding numbers, reflecting the underlying Z topology. We further clarify how a weak perturbation suppresses the non-Hermitian skin effect while preserving the sublattice-symmetry-protected invariant associated with Majorana zero modes. The predicted winding numbers are verified by open-boundary spectra, where one or multiple pairs of zero-energy boundary modes appear consistently with the bulk invariant. We also examine the stability of these modes against onsite disorder by examining the zero-mode energy, the bulk gap, and the inverse participation ratio. Our results provide a systematic and efficient route to constructing topological phase diagrams for higher-winding non-Hermitian topological superconductors.
Dilute Pb in Ge materials fabricated by ion implantation and pulsed laser melting
Germanium lead (GePb) alloys have shown promising potential as a material platform for fabricating mid-infrared photodetectors, where the Pb content enables tuning of the bandgap. However, fabricating such devices using GePb is challenging because the equilibrium solid solubility of Pb in Ge is in the parts per million range. Here, we synthesize the metastable GePb alloy by Pb implantation into Ge, followed by pulsed laser melting. By varying the ion implantation and melting conditions, we identify a processing window that yields GePb alloy films of high crystalline quality, with a substitutional Pb amount of at least 1.6 × 1015 Pb atoms/cm2, which is equivalent to a Pb concentration of around 0.36 at. %, more than 3 orders of magnitude above the equilibrium solubility. These results establish a pathway to fabricating GePb for mid-infrared photodetection applications using non-equilibrium ion implantation, ultra-rapid melting, and solidification.
A sector-shaped acoustic metamaterial for broadband and wide-angle sound absorption
Maintaining stable absorption performance at large oblique incidence while achieving broadband sound absorption remains a major challenge for conventional sound-absorbing materials. To address this issue, a sector-shaped acoustic metamaterial composed of two-dimensional gradient waveguides and a porous backing cavity is proposed to achieve broadband and wide-angle sound absorption. By arranging the entrances of the two-dimensional gradient waveguides in a fan-shaped configuration spanning different azimuthal directions, incident sound waves from various directions can be efficiently guided into the structure, which reduces the dependence of absorption performance on the angle of incidence. Meanwhile, the multiple narrowband resonant responses induced by the gradient waveguides are coupled and smoothed through the damping effect of a porous backing cavity, enabling continuous broadband absorption. Numerical simulations demonstrate that the proposed structure maintains stable and high absorption over a broad frequency range of 500–3400 Hz for incidence angles from 0° to 75°, and remains effective even under near-grazing incidence at 80°. Comparative results further demonstrate that, under large oblique incidence, the proposed metamaterial maintains higher absorption levels across a wide frequency range than conventional porous absorbers and sonic black hole structures. These findings provide an effective design strategy for compact broadband sound absorbers with enhanced angular robustness.
Electric-field dependence of cycle endurance in HfO2-based ferroelectric capacitors
The cycle endurance characteristics of HfO2-based ferroelectric (FE-HfO2) capacitors were systematically investigated in terms of area, temperature, film thickness, and ferroelectric polarization. Cycle endurance exhibited distinct electric-field dependent behavior, which is classified into low, middle, and high field regimes. For area, the electric-field dependence does not change with area. The endurance cycle followed the Weibull distribution, and the Weibull slope is small at low field. For temperature, the electric-field dependence does not change with temperature. Thermal activation energy is almost constant with electric field. The trap generation rate is large at low field. For thickness, endurance and remanent polarization (Pr) had high correlation in electric-field dependence. Thicker ferroelectric capacitors show lower inflection points in electric-field dependence between low-field and middle-field. For polarization, cycle endurance has a universal relationship with Pr, comprehending electric field and temperature. Taking the analysis above into account, the cycle endurance of FE-HfO2 capacitors can be described by Pr and relevant oxygen vacancies. At low field, cycle endurance is determined by the initial oxygen-vacancy rich region non-uniformly generated in the fabrication process. At middle field, dipole pinning is released, and oxygen vacancies are migrated and redistributed by polarization switching. The breakdown path is formed through the redistributed oxygen vacancies. At high field, the initial oxygen vacancy rich region causes high leakage current and accelerates the breakdown. It is a practical method to evaluate cycle endurance vs Pr for reliability assessment of FE-HfO2 capacitors.
Angle-dependent magnetotransport and quantum interference effect in type-II topological Dirac semimetal PtSe2
We report the angle-dependent magnetoresistances (MRs) of platinum diselenide (PtSe2) in the Dirac semimetal phase. The negative longitudinal MR observed in parallel fields persists up to ∼50 K, which is quantitatively consistent with the chiral anomaly of Dirac fermions. When the field is perpendicular to the current, a low-field transition from positive to negative transverse MR is observed between 2 and ∼20 K, which is closely related to the quantum interference between time-reversed scattering paths, as well as the spin–orbit coupling strength. Our results reveal that the small-energy-transfer electron–electron scattering dominates the dephasing process in our PtSe2 films, providing experimental evidence for quantum interference transport in type-II Dirac fermion systems.
From drop impact to cellular response: Transient interfacial force fields, contact-line physics, and mechanotransduction in complex biofluids
Drop impact is a classical problem in fluid mechanics, yet its implications for biological systems remain largely unexplored. Upon impact, droplets generate transient interfacial force fields composed of localized pressure, shear, and extensional stresses that evolve over microsecond-to-millisecond timescales. In complex biofluids and at soft interfaces, these stresses are not simply dissipated, but are redistributed and transformed through structure–flow coupling, dynamic wetting, contact-line motion, and interfacial compliance. This Perspective develops a multiscale physical framework linking drop-impact hydrodynamics to microstructural dynamics in complex fluids and to the transmission of mechanical signals across soft biological interfaces. Particular emphasis is placed on the physics of stress localization near the advancing contact line, the role of classical and soft-matter dimensionless groups in governing impact response, and the conditions under which transformed stresses may perturb cellular mechanosensitive pathways. To quantify this coupling, an impact–mechanotransduction number is introduced as a dimensionless measure relating transmitted impact stress to characteristic cellular prestress. Within this framework, drop impact is recast not only as a transport and deformation process, but also as a source of impulsive mechanical forcing in soft matter and biointerface systems. These ideas define a new direction, impact-driven mechanobiology, and establish a physically grounded basis for future theoretical, experimental, and translational studies of fluid–biological interactions.