Addressing these challenges, the research team pioneered a dry-transfer technique utilizing a high-dielectric constant oxide interlayer of aluminum oxide (Al₂O₃), enabling the direct, contamination-free transfer of four-inch single-crystalline MoS₂ films grown on sapphire substrates to flexible platforms. This sophisticated approach circumvents the adverse effects of wet chemistry, substantially preserving the intrinsic electronic characteristics of the MoS₂ material. The breakthrough creates new possibilities for wafer-scale, high-performance flexible electronics, bridging the gap between laboratory-scale demonstrations and practical, manufacturable devices.

A key feature of this dry-transfer methodology is the introduction of a thin Al₂O₃ interlayer, which serves as a stable, high-κ dielectric interface facilitating strong adhesion and excellent dielectric properties. The oxide layer protects the fragile MoS₂ throughout the transfer process, preventing contamination and mechanical damage that frequently occur in polymer-assisted transfer methods. The resultant MoS₂ films maintain their pristine single-crystalline nature post-transfer, which is critical for achieving superior electronic performance in flexible semiconductor components.

Field-effect transistor (FET) arrays constructed using this innovative dry-transfer technique demonstrate remarkable electrical parameters comparable to their rigid substrate counterparts, showcasing the technological potential of this approach. Devices exhibit a maximum electron mobility of 117 cm² V⁻¹ s⁻¹, indicative of high-quality conduction channels within the flexible MoS₂ films. Moreover, the subthreshold swing reaches as low as 68.8 mV dec⁻¹, signaling excellent gate control and energy efficiency—crucial factors for low-power electronics. The on/off current ratio, a measure of switching capability, attains an impressive value of 10¹², ensuring reliable digital logic operations.

Moving beyond individual transistors, the researchers successfully fabricated flexible inverters operating in the subthreshold regime, achieving a voltage gain of 218. Such high gain values reflect the transistors’ robust amplification capabilities essential for flexible integrated circuits. Impressively, the power consumption of these devices is measured at only 1.4 picowatts per micrometer, positioning them among the most energy-efficient flexible semiconductors to date. These characteristics underscore the feasibility of deploying MoS₂-based electronics in ultralow-power flexible systems with high functional density.

The versatility of the dry-transfer approach is further demonstrated by its application in an active-matrix tactile sensing system integrated onto a robotic gripper. This innovative platform leverages the flexible MoS₂ transistor arrays to perform real-time tactile mapping and object recognition, showcasing the material’s utility in complex sensing and artificial intelligence applications. The integration onto a robotic interface highlights the potential of this technology for next-generation wearable devices, smart robotics, and human-machine interaction systems that demand conformability and robustness.

The authors emphasize that this advancement could revolutionize the fabrication of flexible electronic devices by enabling scalable production of high-performance 2D semiconductor films without resorting to deleterious wet chemical processes. This dry-transfer strategy is poised to accelerate the commercialization of flexible electronics by aligning with existing wafer-scale manufacturing protocols, a crucial step toward widespread industrial adoption. The technique’s compatibility with large-area substrates and industrial scalability marks a significant stride toward practical flexible semiconducting circuits.

One of the noteworthy implications of this work is the preservation of the MoS₂’s monocrystalline quality throughout the transfer and integration processes. Maintaining a single-crystal structure is vital for minimizing grain boundary defects and charge trap sites that typically degrade electronic properties. The retention of crystallinity ensures stable device performance over extended operational lifetimes and under mechanical strain, a key requirement for flexible electronics subjected to bending and twisting stresses during use.

Furthermore, the use of an Al₂O₃ interlayer provides an additional engineering dimension via its high dielectric constant, which improves electrostatic gating in transistor devices. This strategic integration enhances gate capacitance, enabling better modulation of charge carriers in the ultrathin MoS₂ channel. The result is an optimized field-effect transistor operation with reduced threshold voltage and improved switching characteristics, which collectively contribute to enhanced device efficiency and speed.

This research also addresses longstanding reliability concerns associated with 2D material-based devices on flexible substrates. By eliminating polymer residues and solvent-induced defects typically introduced during wet transfers, the oxide dry-transfer process significantly reduces hysteresis effects and charge scattering in MoS₂ devices. This results in more stable, repeatable electrical responses, critical for sophisticated applications such as flexible displays, sensory skins, and wearable electronics that require consistent functionality over millions of bending cycles.

The fabrication process’s compatibility with standard semiconductor manufacturing techniques is another compelling advantage of this approach. The use of sapphire substrates for initial chemical vapor deposition growth of MoS₂ ensures the availability of large-area, single-crystalline films, which can then be seamlessly moved onto flexible circuits through the dry transfer. This synergy between high-quality material synthesis and clean transfer enriches the prospects for integrating 2D semiconductors into commercial flexible electronic platforms.

By introducing a scalable dry-transfer technique that preserves the electronic excellence of single-crystal MoS₂, this study charts a clear path forward for the field of flexible electronics. It signals a transformative approach where device performance is no longer sacrificed at the altar of mechanical flexibility, but instead fully harnessed and optimized. Future iterations of this process may extend to other 2D materials, broadening the palette of atomically thin semiconductors readily deployable in flexible, stretchable, and wearable electronic applications.

The demonstration of a real-time tactile sensing system capable of recognizing objects and mapping pressure patterns underlines the practical impact of this technology. Flexible electronics incorporating MoS₂ transistors can enhance robotic dexterity and tactile perception, opening new frontiers in soft robotics and interactive wearable feedback devices. The coupling of mechanical flexibility with high electronic performance invites unprecedented innovation in areas ranging from biomedical sensors to adaptive human-machine interfaces.

This work also sets an important benchmark for the power efficiency of 2D semiconductor devices on flexible substrates. Achieving power consumptions as low as a few picowatts per micrometer fulfills the demanding criteria for battery-powered and energy-harvesting wearable devices. Such remarkable power efficiency, coupled with high gain and electrical stability, suggests that MoS₂-based flexible electronics will play a critical role in the development of sustainable, long-lasting, and miniaturized electronic systems.

In conclusion, the wafer-scale integration of single-crystalline MoS₂ onto flexible substrates using a high-κ oxide dry-transfer method represents an unprecedented leap forward in flexible electronics fabrication. By preserving the pristine electronic properties of MoS₂ and eliminating contamination sources, this technology enables flexible devices with performance metrics equal to rigid counterparts, while delivering the mechanical resilience and form factors required for the future of wearable and integrated electronics. The research opens exciting new pathways for commercial-scale, flexible semiconductor devices that marry ultra-thin 2D materials with advanced oxide dielectrics.

Subject of Research: Wafer-scale integration of single-crystalline molybdenum disulfide for flexible electronics.

Article Title: Wafer-scale integration of single-crystalline molybdenum disulfide for flexible electronics using oxide dry transfer.

Article References:
Xu, X., Chen, Y., Shen, J. et al. Wafer-scale integration of single-crystalline molybdenum disulfide for flexible electronics using oxide dry transfer. Nat Electron (2026). https://doi.org/10.1038/s41928-026-01598-0

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s41928-026-01598-0

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

However, in a new pioneering study published in Nature, researchers have shattered this prevailing notion by demonstrating that remote epitaxy can occur at distances markedly greater than previously thought possible, reaching up to 2 to 7 nanometers. Such an expansion in the effective range of remote interactions fundamentally challenges the existing theoretical framework and opens new vistas for the design and engineering of epitaxial systems. The experimental work centers on multiple material systems, such as CsPbBr_3 film on an NaCl substrate, KCl film on a KCl substrate, and particularly ZnO microrods grown on GaN. These platforms not only validate long-distance remote epitaxy but also reveal intriguing defect-mediated mechanisms underpinning these phenomena.

Long-distance remote epitaxy’s success hinges significantly on the nature and behavior of the substrate’s atomic potential fields. Conventionally, it was assumed that the electric field fluctuations, which act as the guiding template for epitaxial alignment, diminish exponentially within a couple of atomic layers, rendering the substrate’s influence negligible beyond a sub-nanometer scale. Yet, surprisingly, this new research reveals a contrary reality where atomic dislocations and defects within the substrate act as conduits or enhancers for these long-range interactions. In the case of ZnO microrods grown on GaN, detailed microscopic analyses showed a direct correlation between the presence of dislocations in the GaN substrate and the quality of remotely epitaxial growth.

What makes these findings particularly transformative is how they redefine the spatial constraints of remote epitaxy and suggest a novel paradigm wherein engineered defects within the substrate can be harnessed to facilitate remote interaction over unexpectedly large distances. Such defects essentially act as long-range conduits for the epitaxial template, preserving the crystallographic registry between substrate and film even when physically separated by nanometric spacer layers. This insight offers a strategic lever for optimizing the epitaxial process in systems that include atomically thin insulating layers or other intermediate films, vastly broadening the applicability of remote epitaxy.

The researchers also meticulously demonstrated the practical implications of this phenomenon by achieving high-quality epitaxial films in all targeted systems. The CsPbBr_3 film on NaCl and KCl film on KCl exemplify layered ionic compounds, whereas the ZnO/GaN system showcases a semiconductor heterostructure. These successful demonstrations emphasize the versatility of long-distance remote epitaxy across different classes of materials, reinforcing its potential impact on the semiconductor industry. Each of these systems retains crystallographic continuity despite their interposing spacer layers that previously would have been thought to completely suppress epitaxial templating.

One of the critical technical breakthroughs facilitating these discoveries was the ability to accurately characterize the atomic-scale interactions and defect structures within the substrates. Advanced electron microscopy techniques allowed visualization of dislocations correlating precisely with remotely grown ZnO microrods, providing compelling evidence of the role these defects play as mediators of long-distance epitaxy. This synergy between experimental observation and theoretical insight helped clarify why remote epitaxy could be maintained over distances well beyond 1 nm, and even up to 7 nm.

This research carries profound implications for future device engineering. The ability to maintain epitaxy remotely over larger distances means that films can be grown on substrates without intimate physical contact, allowing the insertion of functional interlayers such as buffers or dielectric spacers that can fine-tune electronic, optical, or mechanical properties. In flexible electronics, for instance, this could enable the growth of high-performance semiconductor films on bendable or stretchable substrates, with the film’s crystalline quality uncompromised despite the presence of intermediate layers necessary for mechanical compliance.

Moreover, harnessing defect-mediated long-distance interactions extends the toolkit available to materials scientists and engineers for designing novel heterostructures. It proposes a pathway to intentionally introduce and pattern defects in the substrate, effectively “programming” the spatial epitaxial relationship and film registry. This level of control was previously unattainable in remote epitaxy and may unlock new possibilities for complex architectures, including vertically stacked layers with precisely controlled interfaces essential for quantum devices or advanced optoelectronics.

While the theoretical community will need to revisit existing models to accommodate these extended interactions, the experimental findings provide a robust foundation to inspire new theories that factor in defect-assisted coupling at the nanometer scale. Such theories might delve into the precise electrostatic and strain fields generated by dislocations and their capacity to stabilize epitaxial orientation remotely. Understanding these mechanisms in finer detail would enable predictive design and optimization of remote epitaxial growth across a broader spectrum of materials.

The discovery of long-distance remote epitaxy also invites a re-examination of other interfacial phenomena governed by atomic-scale potentials. It suggests that similar defect-mediated remote interactions might influence processes like catalytic reactions, phase transformations, and charge transport at interfaces separated by nanoscale distances. Cross-disciplinary exploration of these effects could lead to unexpected innovations beyond epitaxial growth, including energy conversion, sensor technologies, and nanoscale patterning.

In summary, the unveiling of long-distance remote epitaxy is a paradigm-shifting advance, breaking the previous dogma of sub-nanometer epitaxial coupling limits. By showing that defect-engineered substrates can mediate remote epitaxial alignment over distances multiple times greater than expected, this work expands the horizons of materials science and device fabrication. Its implications ripple across semiconductor manufacturing, flexible electronics, nanotechnology, and beyond, heralding a new era of precise, scalable, and versatile epitaxial engineering.

As the research community digests and builds upon these exciting findings, we anticipate rapid developments in both experimental capabilities and theoretical frameworks. The marriage of sophisticated characterization tools with nanoscale defect engineering promises a future where remote epitaxy guides the construction of unprecedented materials and devices. The ability to tailor interfaces across nanometric gaps with atomic precision will undoubtedly fuel innovative technologies that shape the landscape of next-generation electronics and photonics.

This breakthrough, detailed in a seminal publication in Nature by Jia, Xin, Potter, and colleagues, serves as a fundamental milestone. It will drive reinvention in how we conceive and fabricate heterostructures, emphasizing the critical yet previously underappreciated role of defect-mediated long-distance interactions. The stage is set for an electrifying chapter in crystal growth and materials science, propelled by the transformative power of remote epitaxy—far beyond what was once imagined possible.

Article References:
Jia, R., Xin, Y., Potter, M. et al. Long-distance remote epitaxy. Nature (2025). https://doi.org/10.1038/s41586-025-09484-z