Traditional 3D printing approaches typically rely on thermal or photochemical processes to solidify resins and polymers. However, these modalities often encounter limitations when miniaturizing complex geometries on pliable materials, particularly at microscale dimensions required for lab-on-a-chip systems and soft microfluidics. Proximal sound printing circumvents such bottlenecks by deploying highly localized ultrasound energy to initiate polymerization reactions in liquid monomers precisely where needed. This sub-millimeter accuracy is achieved by positioning the ultrasound transducers closer to the target substrate, effectively focusing the acoustic energy and enabling fine control over solidification.

The science underpinning this innovation revolves around the capacity of focused sound waves to induce chemical cross-linking in photo- and thermo-sensitive polymers without relying on external heat or light sources. Unlike previous direct sound printing techniques developed by the same research group, which demonstrated proof-of-concept but suffered from limited resolution and reproducibility, this proximal approach achieves vastly improved feature size control and power efficiency. The reduction in acoustic power requirements not only conserves energy but also minimizes thermal deformation of delicate polymeric materials, leading to enhanced structural fidelity.

One of the most remarkable outcomes of this technique is its ability to fabricate complex assemblies comprised of multiple materials and heterogeneous structures in a single, streamlined printing process. This multi-material printing capability is a critical advantage for constructing functional microsystems exhibiting diverse properties, such as flexible strain sensors integrated directly with microfluidic circuitry for real-time biochemical analysis. The ability to pattern these devices directly on soft substrates heralds new possibilities in wearable health monitors and implantable biomedical devices that demand both miniaturization and mechanical compliance.

Concordia’s team led by Professor Muthukumaran Packirisamy and PhD candidate Shervin Foroughi, collaborating with Mohsen Habibi from the University of California at Davis, has published their findings in the prestigious journal Microsystems & Nanoengineering. Their published study meticulously details experimental setups where focused ultrasound transducers were operated in close proximity to silicone and other polymeric substrates, triggering localized cross-linking reactions and thus solidifying the material layer-by-layer into finely detailed three-dimensional microstructures.

The implications of proximal sound printing extend beyond the laboratory and poised for industrial relevance, particularly in scenarios demanding rapid prototyping of microdevices with stringent dimensional tolerances. This technique’s enhanced repeatability and precision potentially reduce material waste and shorten production cycles, making it an appealing alternative to conventional lithography or laser-based processes which can be prohibitively expensive and less adaptable to soft polymeric materials.

Moreover, the sound-based printing approach addresses critical challenges in microfabrication where ultraviolet or visible light penetration is limited, or where heat-sensitive components preclude the use of traditional thermal curing. The ultrasound-induced polymerization mechanism thus constitutes a non-invasive alternative that expands the materials palette available for next-generation microelectronics and sensing platforms.

Looking forward, this technology promises transformative impacts on the development of soft robotics, flexible electronics, and portable diagnostic tools. The capacity to print intricate microchannels, integrated sensors, and responsive polymer structures directly onto flexible bases streamlines device packaging and enhances mechanical robustness. Such integration facilitates the production of lightweight, adaptable medical devices and wearable systems capable of continuous health monitoring or environmental detection in real time.

The research team acknowledges the foundational role of earlier sound printing methods, emphasizing that the critical advance of reducing the standoff distance between the ultrasound source and the printing interface grants unprecedented control over feature geometry and consistency. By employing proximal sound printing, they achieved features as small as tenths of a millimeter, representing a roughly tenfold improvement over their previous demonstrations.

From a technical perspective, the key to this improvement lies in the manipulation of acoustic focal zones and the refinement of polymer chemistry to optimize responsiveness to ultrasound stimuli. The researchers tailored polymer formulations to achieve rapid and reproducible curing kinetics when subjected to controlled ultrasonic intensities. This synergy of materials engineering and acoustics enables direct fabrication of microstructures without intermediate masking or post-processing steps.

Given these advances, proximal sound printing stands to revolutionize fabrication workflows in laboratories and factories where microscale devices form the backbone of innovation. This technology offers a versatile, energy-efficient, and adaptable route to creating next-generation microsystems crucial for biomedical engineering, sensor technologies, and nanomanufacturing.

Financial support for this research was provided by the Natural Sciences and Engineering Research Council of Canada (NSERC), reflecting the strategic importance of this innovation in advancing Canadian and global capabilities in advanced manufacturing and materials science.

Subject of Research: Not applicable
Article Title: Proximal sound printing: direct 3D printing of microstructures on polymers
News Publication Date: 8-Jan-2026
Web References: https://www.nature.com/articles/s41378-025-01035-w
References: Muthukumaran Packirisamy, Mohsen Habibi, Shervin Foroughi, “New sound-based 3D printing method enables finer, faster microdevices,” Microsystems & Nanoengineering, DOI: 10.1038/s41378-025-01035-w
Image Credits: Concordia University
Keywords: Nanotechnology, Nanofabrication, Polymer engineering

At the heart of this innovation lies the sophisticated interplay of nonlinear optical effects within specially engineered fluorotellurite glass fibers. Unlike conventional silica fibers, fluorotellurite glasses exhibit superior mid-infrared transparency and heightened nonlinear responses, which make them ideal candidates for advanced supercontinuum generation. The recent study, spearheaded by Wang et al., meticulously demonstrates that centimeter-scale lengths of these fibers can facilitate the formation of Raman solitons—stable, self-reinforcing pulses of light maintained through a precise balance of dispersion and nonlinearity—tuned beyond 4 micrometers.

Raman solitons represent a fascinating regime in nonlinear fiber optics, arising from stimulated Raman scattering processes. These solitons effectively transfer energy from a pump laser to longer wavelengths, enabling enormously broadened spectral outputs. However, achieving Raman solitons at wavelengths beyond 4 μm has historically been impeded by material losses and fiber fabrication limits. The fluorotellurite fiber employed in this study circumvents these constraints with its extended mid-infrared transmission window and optimized nonlinear coefficients, thus supporting the seamless extension of Raman solitons deeper into the mid-infrared domain.

Moreover, the emergence of dispersive waves concomitant with Raman soliton generation adds a compelling dimension of tunability and spectral shaping. Dispersive waves, generated via phase-matched interactions between solitons and their surrounding medium, permit the emission of radiation at wavelengths distant from the soliton carrier. In this study, the researchers successfully harnessed this phenomenon to produce wavelength components considerably beyond 4 micrometers within the same short fiber section, establishing a compact, multifunctional light source essential for integrated photonic systems.

The fiber fabrication process itself reflects a confluence of precision materials science and optical engineering. Employing fluorotellurite glasses composed of tellurium oxide, the team meticulously crafted fibers with carefully controlled core and cladding dimensions, optimizing dispersion profiles essential for supporting the nonlinear dynamics at play. Significantly, these fibers are only a few centimeters in length—an order of magnitude shorter than typical mid-infrared supercontinuum sources—highlighting the efficiency and integrability of the approach.

Experimental verification of the Raman soliton and dispersive wave generation involved pumping the fibers with ultrashort laser pulses in the near-infrared regime. As these pulses propagated through the fluorotellurite medium, nonlinear interactions initiated energy transfer processes, resulting in a cascade that broadened and shifted the output spectrum deep into the mid-infrared. High-resolution spectral measurements confirmed the presence of tunable Raman solitons and dispersive waves peaking beyond 4 μm, validating theoretical models that had previously predicted such outcomes but lacked practical realization.

The tunability aspect is especially pivotal, as adjusting the pump pulse parameters and fiber design enabled control over the generated wavelengths within a broad mid-infrared range. This spectral agility opens avenues for customized light sources tailored to specific applications, from the detection of molecular fingerprints in gas sensing to targeted tissue imaging in biomedicine. The compactness and potential for fiber integration further amplify the technology’s appeal for field-deployable instrumentation.

From a scientific perspective, this achievement underscores the critical role of nonlinear fiber optics in pushing the boundaries of accessible wavelengths. Traditional mid-IR sources such as quantum cascade lasers, while powerful, often suffer limitations in tunability and bandwidth. By contrast, Raman soliton and dispersive wave generation in nonlinear fibers leverage inherent material nonlinearities, enabling a flexible and scalable platform that can be continuously refined through materials and structural engineering.

Additionally, the study’s insights into phase matching conditions and soliton dynamics provide a valuable framework for future explorations into tailored nonlinear optical phenomena. Understanding how dispersion engineering in unconventional glass fibers affects soliton evolution and dispersive wave emission could prompt innovations in frequency comb generation, ultrafast spectroscopy, and optical communications—a testament to the versatility of the approach.

Potential challenges do remain, notably regarding the attenuation and stability of fluorotellurite fibers over extended periods and under varying environmental conditions. While the fibers demonstrate exceptional nonlinear performance, their mechanical robustness and manufacturability at industrial scales require further development. Nonetheless, the proof-of-concept presented by Wang and colleagues offers a compelling foundation for ongoing technological refinement.

This research also invites deeper examination of the fundamental physics governing light-matter interactions in heavy metal oxide glasses. The intricate balance between nonlinear effects, dispersion management, and Raman gain profiles in these materials offers fertile ground for pushing mid-infrared photonics into uncharted territories, potentially unlocking novel nonlinear mechanisms beyond Raman soliton formation.

The integration potential of these centimeter-length fluorotellurite fibers with existing photonic architectures cannot be overstated. Their compact design aligns with the contemporary thrust towards miniaturized, chip-scale mid-infrared sources, which are crucial for portable sensing platforms and integrated lab-on-fiber devices. Such integration could democratize access to mid-infrared photonics, catalyzing widespread adoption across scientific and industrial sectors.

Beyond the immediate technological implications, this study signifies a paradigm shift in how mid-infrared light sources may be conceptualized. Rather than relying on bulky and complex laser systems, nonlinear fiber optics now offers a pathway to versatile, tunable, and compact sources, potentially transforming instrumentation landscapes in environmental monitoring, chemical analysis, and medical diagnostics alike.

In conclusion, the generation of tunable Raman solitons and dispersive waves beyond 4 μm in centimeter-length fluorotellurite fibers marks a seminal advance in nonlinear photonics. By harnessing the unique properties of fluorotellurite glass and finely balancing nonlinear optical effects over remarkably short fiber lengths, Wang et al. have opened a new frontier in mid-infrared light source technology. As research builds on these findings, the horizon for compact, tunable, and powerful mid-IR photonic devices appears more promising than ever.

Subject of Research: Nonlinear fiber optics and mid-infrared light source development

Article Title: Generation of tunable Raman soliton and dispersive wave beyond 4 μm in centimeter-length fluorotellurite fibers

Article References:
Wang, J., Wang, S., Zhou, X. et al. Generation of tunable Raman soliton and dispersive wave beyond 4 μm in centimeter-length fluorotellurite fibers. Light Sci Appl 14, 340 (2025). https://doi.org/10.1038/s41377-025-02045-z

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s41377-025-02045-z

Quantum magnetometry hinges on exploiting the unique behaviors of quantum particles when exposed to magnetic fields. By manipulating quantum states, researchers can detect minute variations in magnetic fields with unparalleled precision. However, this revolutionary capability prompts two pivotal inquiries: Is there an ultimate, fundamental limit to the sensitivity that such quantum magnetometers can attain? And how definitively can one assert that a given magnetometer’s performance is truly quantum mechanical rather than classical in nature?

Addressing these questions, Professor Hong Guo and his team at Peking University have recently presented a comprehensive perspective that elucidates the intrinsic sensitivity boundaries of quantum magnetometers by examining three fundamental approaches to evaluating these limits. The team’s analysis reveals that, despite differing in methodology, these approaches share underlying principles dictated by quantum physics and thermodynamics, providing a holistic understanding of magnetometer performance constraints.

The first approach focuses on the noise characteristics intrinsic to quantum measurement processes. Quantum noise — arising from phenomena such as shot noise, quantum projection noise, and back-action — imposes variability that fundamentally restricts measurement precision. By characterizing and quantifying these noise sources, researchers can derive sensitivity limits that define how finely a magnetic field can be resolved, despite the unavoidable statistical fluctuations inherent to quantum systems.

Complementing this, the second perspective involves quantum parameter estimation theory, a rigorous mathematical framework that leverages quantum Fisher information to establish bounds on the precision of parameter measurements, including magnetic field strength. This approach formalizes how quantum entanglement and coherence can enhance sensitivity beyond classical limits, while also specifying fundamental barriers that cannot be breached, rooted in the Cramér-Rao bound and related quantum statistical principles.

The third evaluation method scrutinizes the energy resolution limit, where sensitivity is tied to thermodynamic and energetic considerations. By relating the sensing process to thermodynamic costs and information theory, this perspective links the minimal achievable energy expenditure to the precision in magnetic field detection. The intrinsic interplay between energy, information, and measurement fidelity highlights thermodynamics as a governing principle that constrains quantum magnetometer capabilities.

Crucially, Professor Guo’s team demonstrates that these three approaches are not isolated but rather interconnected facets of a unified theoretical structure. They all emerge naturally from fundamental principles such as the Heisenberg uncertainty principle, the framework of statistical estimation, and the thermodynamics of information. This interrelation underscores that the sensitivity boundaries of quantum magnetometers are anchored in deep physical laws rather than technological limitations, thereby framing a universal metric for evaluating sensor performance.

Furthermore, the analysis addresses the critical question of when a magnetometer can be legitimately classified as “quantum.” By examining the relationships between sensitivity limits and quantum features such as coherence and entanglement, the study provides criteria that distinguish genuinely quantum-enhanced sensing devices from classical counterparts that merely mimic quantum behaviors superficially. This discrimination is essential for guiding both theoretical research and experimental implementation toward truly quantum technologies.

The implications of this work extend beyond theoretical insight; it offers practical guidance for experimentalists seeking to optimize quantum magnetometer designs. By illuminating the fundamental constraints and their origins, researchers are empowered to fine-tune device architectures, choose appropriate quantum systems, and devise measurement protocols that approach or saturate these limits, thereby achieving unprecedented sensitivity levels in real-world applications.

Quantum magnetometers continue to transform disciplines by enabling new experiments in fundamental physics, such as probing exotic quantum states, detecting subtle magnetic signatures in biological tissues non-invasively, and performing remote environmental monitoring with unmatched precision. These applications benefit directly from the enhanced understanding of sensitivity limits and quantum resource requirements elaborated by Professor Guo’s research.

The study’s insights also resonate with ongoing efforts to integrate quantum sensors into emerging quantum technologies and quantum information processing platforms. By mapping the interplay between quantum coherence, measurement precision, and thermodynamic efficiency, the research provides a conceptual bridge linking sensor development with broader quantum engineering challenges.

Advancing the frontier of quantum magnetometry necessitates a robust comprehension of these underlying physical principles. As quantum technologies mature, defining and respecting these fundamental performance bounds will be imperative to harness their full potential without succumbing to unrealistic expectations or misinterpretations of quantum advantage.

In summary, this comprehensive analysis of the sensitivity limits of quantum magnetometers unifies different conceptual frameworks under a common theoretical umbrella rooted in the bedrock of quantum mechanics and thermodynamics. It delineates clear boundaries for quantum-enhanced magnetic sensing, offers criteria to establish truly quantum operation, and sets the stage for future experimental breakthroughs that push quantum magnetometry toward its ultimate performance frontier.

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Subject of Research: Quantum Magnetometry and Sensitivity Limits

Article Title: [Not provided]

News Publication Date: [Not provided]

Web References: http://dx.doi.org/10.1093/nsr/nwaf129

Image Credits: ©Science China Press

Keywords: quantum magnetometer, magnetic field sensing, sensitivity limits, quantum coherence, quantum entanglement, quantum noise, quantum parameter estimation, energy resolution limit, thermodynamics of information, Heisenberg uncertainty principle, quantum sensor optimization