Applied Physics Reviews

Bound states in the continuum (BICs) have emerged as research hotspots in optics and photonics, offering a new paradigm for achieving extreme field localization and enhancing light–matter interactions. Here, we establish for the first time the intrinsic evolution laws of Fabry–Pérot bound states in the continuum (FP-BICs), revealing that the Q factor is inversely proportional to the square of phase/frequency detuning and to the nonradiative decay rate, enabling directional engineering of FP-BIC resonances. We propose an all-dielectric multilayer film metasurface to create an optical resonator and its perfectly mirrored counterpart, inducing FP-BICs and validating the conclusions. We experimentally demonstrated the evolution of the Q factor with frequency detuning, achieving a maximum Q factor of 610 in the visible. Our work offers novel insights into BICs, promising to inspire exotic phenomena and applications.

Controlling and enhancing light–matter coupling at subwavelength scales is an essential requirement in the realm of meta-photonics. Recently, all-dielectric metasurfaces (MSs) governed by the physics of bound states in the continuum (BICs) have emerged as a standout platform for delivering high-quality (Q) factor resonances and near-field electromagnetic hotspots. However, in the terahertz (THz) domain, experimental validation of high-Q BICs resonances with strong robustness and advanced maneuverability in such all-dielectric photonic systems remains a long-standing challenge. Here, we demonstrate a simple and feasible fabrication approach to unlock the full potential of BICs-inspired resonances within the array of silicon cross elliptical resonators. Our results suggest that the designed THz-MS can support two symmetry-protected BICs with a topological charge of ±1 and several accidental BICs with a topological charge of +1 simultaneously. By introducing small perturbations to the individual resonator, the original two symmetry-protected BICs transform into quasi-BICs that bow to the inverse-square law. Astoundingly, for larger symmetry breaking, two additional BICs can be observed in the asymmetric THz-MSs surpass typical inverse-square rule, hence presenting a supererogatory degree of freedom for tailoring BICs resonances on demand. We bear out theoretical findings by transmission experiments implemented on the fabricated samples. We observe experimentally ultrasharp dual quasi-BICs resonances with a highest measured Q factor of up to 371, a level of performance that was previously unattainable with all-dielectric THz-MS on a substrate. The results mark an important step toward enriching the family of BICs and promise exciting opportunities in the field of THz optoelectronic devices and metadevices.

As photonic technologies grow in multidimensional aspects, integrated photonics holds a unique position and continuously presents enormous possibilities for research communities. Applications include data centers, environmental monitoring, medical diagnosis, and highly compact communication components, with further possibilities continuously growing. Herein, we review state-of-the-art integrated photonic on-chip sensors that operate in the visible to mid-infrared wavelength region on various material platforms. Among the different materials, architectures, and technologies leading the way for on-chip sensors, we discuss the optical sensing principles that are commonly applied to biochemical and gas sensing. Our focus is on passive optical waveguides, including dispersion-engineered metamaterial-based structures, which are essential for enhancing the interaction between light and analytes in chip-scale sensors. We harness a diverse array of cutting-edge sensing technologies, heralding a revolutionary on-chip sensing paradigm. Our arsenal includes refractive-index-based sensing, plasmonics, and spectroscopy, which forge an unparalleled foundation for innovation and precision. Furthermore, we include a brief discussion of recent trends and computational concepts, incorporating Artificial Intelligence & Machine Learning (AI/ML) and deep learning approaches over the past few years to improve the qualitative and quantitative analysis of sensor measurements.

The obtention of quantum-grade rare-earth-doped oxide thin films that can be integrated with optical cavities and microwave resonators is of great interest for the development of scalable quantum devices. Among the different growth methods, chemical vapor deposition (CVD) offers high flexibility and has demonstrated the ability to produce oxide films hosting rare-earth ions with narrow linewidths. However, growing epitaxial films directly on silicon is challenging by CVD due to a native amorphous oxide layer formation at the interface. In this manuscript, we investigate the CVD growth of erbium-doped yttrium oxide (Er:Y2O3) thin films on different substrates, including silicon, sapphire, quartz, or yttria stabilized zirconia (YSZ). Alternatively, growth was also attempted on an epitaxial Y2O3 template layer on Si (111) prepared by molecular beam epitaxy (MBE) in order to circumvent the issue of the amorphous interlayer. We found that the substrate impacts the film morphology and the crystalline orientations, with different textures observed for the CVD film on the MBE-oxide/Si template (111) and epitaxial growth on YSZ (001). In terms of optical properties, Er³⁺ ions exhibit visible and IR emission features that are comparable for all samples, indicating a high-quality local crystalline environment regardless of the substrate. Our approach opens interesting prospects to integrate such films into scalable devices for optical quantum technologies.

Nonlinear optics has long been a cornerstone of modern photonics, enabling a wide array of technologies, from frequency conversion to the generation of ultrafast light pulses. Recent breakthroughs in two-dimensional (2D) materials have opened a frontier in this field, offering new opportunities for both classical and quantum nonlinear optics. These atomically thin materials exhibit strong light–matter interactions and large nonlinear responses, thanks to their tunable lattice symmetries, strong resonance effects, and highly engineerable band structures. In this paper, we explore the potential that 2D materials bring to nonlinear optics, covering topics from classical nonlinear optics to nonlinearities at the few-photon level. We delve into how these materials enable possibilities, such as symmetry control, phase matching, and integration into photonic circuits. The fusion of 2D materials with nonlinear optics provides insights into the fundamental behaviors of elementary excitations—such as electrons, excitons, and photons—in low-dimensional systems and has the potential to transform the landscape of next-generation photonic and quantum technologies.

Antimonene, the two-dimensional phase of antimony, appears in two distinct allotropes when epitaxially grown on Bi2Se3: the puckered asymmetric washboard ( α) and buckled honeycomb ( β) bilayer structures. As-deposited antimony films exhibit varying proportions of single α and β structures. We identify the conditions necessary for ordered, pure-phase growth of single to triple β-antimonene bilayers. Additionally, we determine their electronic structure, work function, and characteristic core-level binding energies, offering an explanation for the relatively large chemical shifts observed among the different phases. This study not only establishes a protocol for achieving a single β phase of antimonene but also provides key signatures for distinguishing between the different allotropes using standard spectroscopic and microscopic techniques.

Raman spectroscopy, which enables simultaneous detection of multi-gas components, is considered a valuable tool for gas analysis. However, the weak Raman scattering effect limits its application in the field of high-sensitivity gas detection. In this article, we summarize the principles and characteristics of existing techniques for improving the detection of Raman spectra, from both the perspectives of signal enhancement and noise suppression. Regarding signal enhancement techniques, the main methods include multi-pass cavity enhancement, resonant cavity enhancement, and hollow-core fiber enhancement. As for noise suppression methods, the primary approaches include spatial filtering, shifted excitation Raman difference spectroscopy, polarized Raman spectroscopy, and internal standard correction. Finally, we present and outlook on how to further enhance the sensitivity of Raman spectroscopy based on existing techniques, which can lay the foundation for the future development of robust and easy-to-use gas analysis instruments.

Functional microvasculature is essential for in vitro tissue constructs, ensuring efficient transport of oxygen, nutrients, and waste and supporting vital paracrine signaling for tissue stability. Recent advancements in both direct and indirect 3D bioprinting offer promising solutions to construct complex vascular networks by allowing precise control over cell and extracellular matrix placement. The process from shape printing of microvasculature to function formation involves dynamic shift of bioink mechanical properties, mechanical microenvironments, and mechanobiology of endothelial and supporting cells. This review explores how biomechanical and mechanobiological principles are integrated into the bioprinting process to develop functional microvascular networks. Before printing, a top-level design approach based on these principles focuses on the interactions among biomaterials, cell behaviors, and mechanical environments to guide microvascular network fabrication. During printing, biomechanical design of bioinks for different bioprinting techniques, along with optimized biomechanical factors of bioprinting process, ensures accurate microvascular structure reproduction while maintaining cell viability. After printing, the emphasis is on creating a suitable mechanical environment to modulate the mechanobiology of multiple steps of neovascularization, including initiation, morphogenesis, lumen formation, stabilization, and maturation of functional microvasculature. Finally, we discuss future developments based on biomechanical and mechanobiological design to drive the bioprinting of functionalized microvascular networks.

Smart biomaterials have significantly impacted human healthcare by advancing the development of medical devices designed to function within human tissue, mimicking the behavior of natural tissues. While the intelligence of biomaterials has evolved from inert to active over the past few decades, smart biomaterials take this a step further by making their surfaces or bulk respond based on interactions with surrounding tissues, imparting outcomes similar to natural tissue functions. This interaction with the surrounding tissue helps in creating stimuli-responsive biomaterials, which can be useful in tissue engineering, regenerative medicine, autonomous drug delivery, orthopedics, and much more. Traditionally, material engineering focused on refining the static properties of biomaterials to accommodate them within the body without evoking an immune response, which was a major obstacle to their unrestricted operation. This review highlights and explains various engineering approaches currently under research for developing stimuli-responsive biomaterials that tune their outcomes based on responses to bodily factors like temperature, pH, and ion concentration or external factors like magnetism, light, and conductivity. Applications in soft and hard tissue engineering, 4D printing, and scaffold design are also discussed. The advanced application of microfluidics, like organ-on-a-chip models, extensively benefits from the intrinsic smart properties of biomaterials, which are also discussed below. The review further elaborates on how smart biomaterial engineering could revolutionize biosensor applications, thereby improving patient care quality. We delineate the limitations and key challenges associated with biomaterials, providing insights into the path forward and outlining future directions for developing next-generation biomaterials that will facilitate clinical translation.

Solar-blind UV polarization detection and imaging can reflect more detailed optical information, which is vital for developing next-generation deep UV optoelectronic devices. β-Ga2O3 with ultra-wide bandgap is an ideal candidate for solar-blind UV detection application. However, the bulky nature of Ga2O3 limits its application in miniaturized, integrated and multifunctional devices, and polarization imaging based on Ga2O3 photodetector has not yet been realized. Here, we report a convenient method to prepare 2D β-Ga2O3 flakes via liquid-metal-assisted exfoliation. Benefiting from high crystallinity and polarization-sensitive absorption of prepared ultrathin β-Ga2O3 flake in monoclinic structure, the β-Ga2O3 photodetector exhibits an ultra-fast response speed (100/78 μs for rise/decay time) and a prominent anisotropy ratio (∼2.8) of polarization photoresponse under 265 nm illumination. An unambiguous detection of linearly polarized light has also been realized by the double symmetry-breaking of twisted β-Ga2O3 photodetectors. Moreover, a four-layer twistedly stacked detection system further enables a one-step and well-defined polarization imaging with high resolution (150 × 150 pixels) to acquire spatial polarization information. This work presents a novel strategy for preparing ultrathin 2D gallium oxides and demonstrates a promising route to realize well-defined solar-blind polarization imaging in a simple manner.

Nuclear energy emerges as a promising and environmentally friendly solution to counter the escalating levels of greenhouse gases resulting from excessive fossil fuel usage. Essential to harnessing this energy are nuclear batteries, devices designed to generate electric power by capturing the energy emitted during nuclear decay, including α or β particles and γ radiation. The allure of nuclear batteries lies in their potential for extended lifespan, high energy density, and adaptability in harsh environments where refueling or battery replacement may not be feasible. In this review, we narrow our focus to nuclear batteries utilizing non-thermal converters such as α- or β-voltaics, as well as those employing scintillation intermediates. Recent advancements in state-of-the-art direct radiation detectors and scintillators based on metal perovskite halides (MPHs) and chalcogenides (MCs) are compared to traditional detectors based on silicon and III-V materials, and scintillators based on inorganic lanthanide crystals. Notable achievements in MPH and MC detectors and scintillators, such as nano-Gy sensitivity, 100 photons/keV light yield, and radiation hardness, are highlighted. Additionally, limitations including energy conversion efficiency, power density, and shelf-life due to radiation damage in detectors and scintillators are discussed. Leveraging novel MPH and MC materials has the potential to propel nuclear batteries from their current size and power limitations to miniaturization, heightened efficiency, and increased power density. Furthermore, exploring niche applications for nuclear batteries beyond wireless sensors, low-power electronics, oil well monitoring, and medical fields presents enticing opportunities for future research and development.

While the development of new solid electrolytes (SEs) is crucial for advancing energy storage technologies, revisiting existing materials with significantly improved knowledge of their physical properties and synthesis control offers significant opportunities for breakthroughs. Na1+xZr2SixP3−xO12 (NaSICON) SEs have recently regained attention for applications in both solid-state and aqueous redox flow batteries due to their improved electrochemical and mechanical properties, along with their inherent electrochemical stability, air robustness, and low manufacturing cost. Recent improvements in NaSICON have primarily targeted macroscopic property enhancements and synthesis techniques. To enable further breakthroughs in the performance of NaSICON SEs, future efforts should focus on understanding how modified synthesis conditions influence atomic and microscopic-scale features, such as conduction channels, electronic structures, phase distributions, and grain boundaries. These features ultimately control ion conductivity, mechanical properties, and electrochemical stability of NaSICON and its interfaces. Here, we review the current understanding of the structure-chemistry-property relationships of NaSICON SEs, focusing on atomic and microscopic levels. First, we introduce the proposed ionic conduction mechanisms in NaSICON crystallites. Then, we explore experimental investigations at phase and grain boundaries to assess ionic conduction and interfacial stability. We also examine strategies to address interfacial challenges such as high resistance and chemical reactions between SEs and electrodes, highlighting the difficulties in analyzing interfaces at the nano/atomic scale. Finally, we provide an outlook on advancing microscopy and spectroscopy techniques to enhance insights into NaSICON SEs ionic conduction and interfacial stability, supporting the development of improved long-duration energy storage devices.

The advent of artificial intelligence—deep neural networks (DNNs) in particular—has transformed traditional research methods across many disciplines. DNNs are data driven systems that use large quantities of data to learn patterns that are fundamental to a process. In the realm of artificial electromagnetic materials (AEMs), a common goal is to discover the connection between the AEM's geometry and material properties to predict the resulting scattered electromagnetic fields. To achieve this goal, DNNs usually utilize computational electromagnetic simulations to act as ground truth data for the training process, and numerous successful results have been shown. Although DNNs have many demonstrated successes, they are limited by their requirement for large quantities of data and their lack of interpretability. The latter results because DNNs are black-box models, and therefore, it is unknown how or why they work. A promising approach which may help to mitigate the aforementioned limitations is to use physics to guide the development and operation of DNNs. Indeed, this physics-informed learning (PHIL) approach has seen rapid development in the last few years with some success in addressing limitations of conventional DNNs. We overview the field of PHIL and discuss the benefits of incorporating knowledge into the deep learning process and introduce a taxonomy that enables us to categorize various types of approaches. We also summarize deep learning principles which are critical to PHIL understanding and the Appendix covers some of the physics of AEMs. A few specific PHIL works are highlighted and serve as examples of various approaches. Finally, we provide an outlook detailing where the field is currently and what we can expect in the future.

The ever-increasing energy demand has highlighted the need for sustainable, low-carbon, and multi-functional energy solutions. Recently, multi-material additive manufacturing (MMAM) has become an emerging processing approach to prototype energy storage and conversion devices by enabling the fabrication of complex systems in a single, streamlined process while offering design freedom to customize end-product properties at precise, user-defined patterns and geometries. Moreover, it provides opportunities to fine-tune interfaces and material compositions at the microscale, opening new avenues for next-generation energy storage and conversion devices. As MMAM is still in its early stages, a comprehensive understanding of the interplay between material chemistry, processing methods, and device design is fundamental to fully realize its potential for developing high-performance energy materials. This review proposes a framework to bridge the gaps between the fundamental principles of processing physics and the practical implementation of various MMAM techniques in fabricating advanced energy storage and conversion devices, highlighting research challenges and future opportunities.

Magnetic properties of crystalline solids are fundamental to a wide range of applications, capturing the attention of a vast scientific community. Thus, engineering magnetic order in materials such as ferromagnetism and antiferromagnetism holds great scientific and technological interest. Defects such as vacancies, interstitials, and dopants induce local perturbations within the crystal lattice. These perturbations locally disturb the entire symmetry of crystals, resulting in symmetry breaking. Oxides, in particular, exhibit intriguing properties when subjected to defects, which can lead to significant modifications in their structural, electronic, and magnetic properties. Such defects in non-magnetic oxides can induce magnetic symmetry breaking, leading to the formation of emergent magnetic domains and orderings. In this review, we focus on the recent progress in magnetic breaking symmetries in materials via defect engineering and present our perspectives on how these may lead to new understanding and applications.

The proximity effect has long been recognized as the primary driver of static transport behavior in superconductor/ferromagnetic heterostructures, yet the understanding of magnetic dynamics in this context remains limited. Here, we demonstrate a significant shift of ferromagnetic resonance spectra in ferromagnetic films placed between two superconductor gating layers. Through deliberate modifications of the interface structure using various insertion layers, we have determined that the superconducting proximity effect has a minimal impact on the modulation of ferromagnetic resonance characteristics. Instead, our findings strongly support very recent theoretical predictions that emphasize the phenomenon of ultrastrong coupling between Kittel magnons and Cooper pairs arising from the superconducting magnetoelectric effect. We propose that this ultrastrong coupling not only provides a precise method for determining superconducting parameters like the London penetration depth but also lays the foundation for the manipulation of spin waves through superconductors in future magnonic circuits.

Optogenetics with high temporal and spatial resolution hold great potentials to replace the traditional drug and electrical stimulation techniques, which calls for optical probing devices with low crosstalk and organic damages. Here, we report a fabrication method of optoelectrical probes for precise modulation of neurons. A linear array of flip-chipped green resonant-cavity μLEDs (RCLED) with an emitting aperture of 50 μm is integrated on Si platform as the stimulation source. Due to the top/bottom Bragg reflectors, the RCLEDs' output light view-angle is narrowed to <90°. The emission wavelength demonstrates remarkable stability under various injection current densities. Under the 50 A/cm² driving current density, the RCLEDs' output optical density is 100 mW/mm² and maximum temperature rise is 0.5 °C, both of which exhibit great improvement compared with those of the optical probes on sapphire substrate. Using these green RCLED probes to stimulate Mac-mCherry photosensitive protein, the analgesia and inhibition effects for medium prefrontal cortex GABAergic neurons are verified. This work provides an effective approach to fabricate integrated microscale light sources for precise stimulation and modulation of neurons, which facilitate the study of complex neural functions.

Wide bandgap semiconductor (WBS) materials have a wide range of applications in radio frequency and power electronics due to their many advantages such as high saturation drift velocity, breakdown voltage, and excellent thermal/chemical stability. Diamond, Ga2O3, GaN, and SiC are typical WBS materials. Reliability studies for these four materials and devices are crucial for WBS applications. Traditional means of reliability studies include, but are not limited to, x-ray diffraction, atomic force microscopy, Raman spectroscopy, and electron microscopy et al. However, most of these methods are ex situ studies after material or device failure and thus have some limitations. In situ transmission electron microscope (TEM) is a favorable technology to observe the degradation and failure process of materials and devices in real time, which may provide effective guidance in material growth, device structure design, device process optimization, and reliability improvement. In recent years, in situ TEM technology has been gradually used by researchers to study WBS materials and devices. In this review, we present a comprehensive and systematic review of in situ TEM works on diamond, Ga2O3, GaN, and SiC materials and devices, with a particular focus on the progress of the technology in the reliability study of such materials and devices. While summarizing the advantages of in situ TEM in the investigation of WBS materials and devices, the review also looks forward to the future of in situ TEM in promoting the study of WBS materials and devices.

Optoelectronic devices, such as photodetectors (PDs), are needed in many applications including high-speed optical communications, robotics, healthcare, and biomimetic visual systems, which require detection and interaction using light. As a result, a wide variety of PDs on planar substrates have been reported using various light sensitive materials and traditional micro-/nano-fabrication technologies. In recent years, considerable efforts have been devoted to developing PDs with flexible form factors and using eco-friendly materials and approaches. These efforts have resulted in exploration of degradable materials and printed electronics as a resource-efficient route for manufacturing and to contain end-of-life issues. This paper reviews such new advances, particularly focusing on flexible PDs based on inorganic (e.g., crystalline silicon, compound semiconductors, metal oxides, etc.) semiconductor nanostructures [e.g., Nanowires (NWs), Nanoribbons (NRs), etc.]. The advantages and disadvantages of various bottom-up and top-down methods explored to realize the nanostructures and the wet (solution-processable) and dry printing and assembly methods to print the nanostructures on flexible substrates, are discussed along with their suitability for various applications. This discussion is supported by a comparative analysis of printed PDs in terms of key performance metrics such as responsivity, detectivity, ILight/IDark ratio, response speed, and external quantum efficiency. This comprehensive discussion is expected to benefit researchers and practitioners from academia and industry interested in the field of printed and flexible PDs.

Quantum states of light, such as fixed photon number (Fock) states, entangled states, and squeezed states, offer important advantages with respect to classical states of light, such as coherent states and thermal states, in different areas: they enable secure communication and distribution of encryption keys, enable realization of sensors with higher sensitivity and resolution, and are considered candidates for quantum computing and simulation applications. To accommodate these applications, suitable methods for generating the quantum states are needed. Today, the quantum states are often produced by a spontaneous nonlinear process in a standard nonlinear material, followed by a series of optical elements necessary for encoding the desired state on the generated photons. In this review, we consider an alternative approach of structuring the nonlinearity of the crystal so that the desired quantum state will be generated directly at the crystal, without the need for additional elements. Our main focus here is on bulk crystals having structured second-order nonlinearity. The rising interest in these nonlinear metamaterials is fueled by advancements in the ability to efficiently simulate and design spontaneous parametric downconversion (SPDC) processes, as well as by new capabilities of structuring the nonlinearity of ferroelectric crystals, either by electric field poling or by laser-induced writing. As a result, nonlinear metamaterials were recently used to directly shape the spatial and spectral correlations of quantum light that is generated in SPDC. The paper covers the theoretical background and the design and fabrication methods of bulk nonlinear metamaterials for generating quantum light, as well as a series of demonstrations of the use of metamaterials in quantum optical applications.

The requirements for high performance, reliability, and longevity in electronic devices, such as power semiconductors and thermal sensors, make effective thermal management a formidable challenge. Thus, understanding lattice dynamics is crucial for regulating thermal conduction, as the intrinsic limit mainly depends on phonon dispersions. Conventionally, thermal conduction is regulated through heat-carrying acoustic phonon manipulation due to their high group velocities, which are widely utilized in materials such as thermal coatings and thermoelectrics. In recent years, with advancements in thermal transport, optical phonons have been of great interest for tuning thermal conduction, with a particular focus on those with special dispersive behaviors; however, the microscopic mechanisms are significantly different. This review aims to provide a comprehensive understanding of the effect of optical phonons, especially those with high weights on thermal conduction in advanced materials, as well as discuss the fundamental mechanisms, including (i) phonon bandwidth, (ii) phonon gap, (iii) avoided-crossing, (iv) phonon nesting/twinning, (v) optical-acoustic phonon bunching, and (vi) multiple optical phonons.

Along with the ever expanding frontiers of photonic applications as the world is fast advancing into the information era, there is a growing market for specialty photonic waveguides and fibers requiring sophisticated structures and materials that conventional manufacturing technologies meet great challenges and difficulties to accommodate. Advanced 3D printing or additive manufacturing possesses great flexibility in structure and diversity in material and is emerging as an essential alternative in developing novel specialty photonic waveguides, fibers, and devices for new photonic applications. This paper reviews 3D printing-based photonic waveguides, fibers, and their applications in terms of basic material and processing techniques, fundamental principles and mechanisms, current research and development, and remaining technical problems and challenges.

As an effective method for thermal management technologies, doping or substitution has been extensively utilized to reduce the lattice thermal conductivity of various materials. Intensive studies have been conducted about the phonon mechanism of isoelectronic alloying since the 1950s. Very recently, the specific role of aliovalent doping was elucidated in the half-Heusler NbFeSb system. Here, we have theoretically and experimentally investigated the mechanism of reducing thermal conductivity through aliovalent doping by combining first-principles calculations and neutron diffraction studies for the case study of the TiCoSb half-Heusler system. The softening of the acoustic branches induced by aliovalent doping can effectively reduce the phonon group velocities. Moreover, the introduction of compensating defects, resulting from changes in the Fermi level, plays a vital role in decreasing the relaxation time of phonons, as demonstrated by the analysis of neutron powder diffraction. Due to these two factors, doping with adjacent elements results in a significant reduction in lattice thermal conductivity (for instance, Ni doping at the Co site in the TiCoSb half-Heusler system), especially in the low-temperature range. Our findings provide valuable insight into the phonon scattering mechanism in aliovalent-doped materials and demonstrate the role of compensating defects in heat transport, which is applicable to other doped semiconductor systems.

Graphene has been one of the most investigated materials in the last decade. Its unique optoelectronic properties have indeed raised it to an ideal and revolutionary candidate for the development of entirely novel technologies across the whole electromagnetic spectrum, from the microwaves to the x-rays, even crossing domain of intense application relevance, as terahertz (THz) frequencies. Owing to its exceptionally high tensile strength, electrical conductivity, transparency, ultra-fast carrier dynamics, nonlinear optical response to intense fields, electrical tunability, and ease of integration with semiconductor materials, graphene is a key disruptor for the engineering of generation, manipulation, and detection technologies with ad hoc properties, conceived from scratch. In this review, we elucidate the fundamental properties of graphene, with an emphasis on its transport, electronic, ultrafast and nonlinear interactions, and explore its enormous technological potential of integration with a diverse array of material platforms. We start with a concise introduction to graphene physics, followed by the most remarkable technological developments of graphene-based photodetectors, modulators, and sources in the 1–10 THz frequency range. As such, this review aims to serve as a valuable resource for a broad audience, ranging from novices to experts, who are keen to explore graphene physics for conceiving and realizing microscale and nanoscale devices and systems in the far infrared. This would allow addressing the present challenging application needs in quantum science, wireless communications, ultrafast science, plasmonics, and nanophotonics.

This study investigates the efficacy of an untethered magnetic robot (UMR) for wireless mechanical and hybrid blood clot removal in ex vivo tissue environments. By integrating x-ray-guided wireless manipulation with UMRs, we aim to address challenges associated with precise and controlled blood clot intervention. The untethered nature and size of these robots enhance maneuverability and accessibility within complex vascular networks, potentially improving clot removal efficiency. We explore mechanical fragmentation, chemical lysis, and hybrid dissolution techniques that combine mechanical fragmentation with chemical lysis, highlighting their potential for targeted and efficient blood clot removal. Through experimental validation using an ex vivo endovascular thrombosis model within the iliac artery of a sheep, we demonstrate direct revascularization of a 13-mm-long, 1-day-old blood clot positioned inside the left common iliac artery. This was achieved by deploying a UMR into the abdominal aorta within 15 min. Additionally, both mechanical fragmentation and hybrid dissolution achieve a greater volume rate of change compared to no intervention (control) and chemical lysis alone. Mechanical fragmentation exhibits clot removal with a median of 0.87 mm³/min and a range of 2.81 mm³/min, while the hybrid approach demonstrates slower but more consistent clot removal, with a median of 0.45 mm³/min and a range of 0.23 mm³/min.