Recent Fundamental and Technological Progress in Micro‐nanotechnologies

Burgeoning interdisciplinary advances and commercial activities in micro-nanotechnologies have already generated the basic knowledge, and early-stage or matured breakthroughs in a diverse landscape of progressive and desirable applications at the forefront of modern research and technology, including medical technology. There are three main reasons for this. The first is the development of new, cost-efficient, and easily implemented micro- and nanofabrication routes that are essential for seamless integration of micro- and nanomaterials in bioelectronics, optoelectronics, and biosensing, and therapeutic and theranostics technologies. The second is the strong prospects for bringing together fundamental knowledge and end-user engagement at the boundaries of materials science, nanotechnology, biomedical engineering, and cellular biology. The third is the extraordinary push toward multidisciplinary research environments that are ideal for pursuing collaborative research across cognate disciplines, including engineering, physics, chemistry, biology, and medicine. This Australian National Fabrication Facility (ANFF) special issue gives a snapshot into the work of leading Australian researchers who have produced fundamental knowledge across a broad spectrum of platforms and applications—knowledge-driven by a new landscape of micro- and nanostructured materials for life sciences, 3D bioprinting for tissue engineering, silicon-based qubits for quantum computing devices, and diverse micro/nanosubstrates for photonic, bioelectronic, and sensing applications—all of them now spurring scientific and technological progress. These advances are underpinned by the collective expertise of the ANFF network, comprising eight nodes at 21 Australian universities and the Commonwealth Scientific & Industrial Research Organisation (CSIRO) (article number 2101995). Customised nanofabrication routes have been developed by our teams: (i) Zhang et al. (article number 2103057) make a significant step toward selectively controlling the growth of highly uniform InGaAs/InP nanowires with quantum wells for optoelectronic device applications and integrated photonic systems; (ii) Alava et al. (article number 2104213) use molecular beam epitaxy to produce ultra-shallow all-epitaxial aluminium gate GaAs/AlxGa1−x as transistors with high electron mobility; (iii) Bo et al. (article number 2100351) engineer ultraporous nanoparticle precursor sheets for maskless patterning of monolithic metal-organic frameworks (MOFs) of nanoscale resolution and up to sub-millimetre thickness on very large surface areas—precursor sheets that readily allow fabrication of functional MOF patterns by a variety of methods, including handwriting with a pen, laser ablation, and focused ion beam, with applications ranging from microfluidic devices to enzymatic reactors; and (iv) Wang et al. (article number 2010296) demonstrate an ultra-sensitive biomarker detection approach in serum, by implementing nanofabrication routes and combining microfluidic device and surface-enhanced Raman spectroscopy. At the microscale, microneedle technology offers the ideal interface with skin. Dervisevic et al. (article number 2009850) demonstrate the use of a transdermal sensing system based on microneedle arrays for pain-free monitoring of interstitial fluid glucose. A review paper by Sementilli et al. (article number 2105247) covers a range of applications and performance for micro-mechanical resonators, and describes the various mechanisms that control elastic energy dissipation. A review by Martyniuk et al. (article number 2103153) cover the enabling micro-electromechanical system optical filter technologies for infrared and terahertz wavelength bands. A particular focus is on a low-size, -weight, and -power solution that delivers mechanically robust spectrally selective sensing for deployment on field-portable platforms. Considerable progress has been made in understanding how new nano-microscale topographies interact with biological systems. The two research papers by Yoh et al., (article number 2104828) and by Carthew et al., (article number 2100881) both demonstrate breakthroughs in controlling a suite of nanofabrication routes for engineering the physical geometry of micro-nanostructures—their density, diameter, height, shape, and hierarchical architectural designs. While Yoh manufactures polymeric nanoneedles of controlled geometry and stiffness for gene-delivery applications, Carthew imprints micro- and nanoscale topographical features into conventional cell cultureware, enabling high-throughput screening for cellular manipulation. Advances in nanoscale manufacturing have led to the rapid development of label-free optical devices. Aoni et al. (article number 2103143) demonstrate novel self-intensified optical sensing based on resonant dielectric metagratings. The sensing approach uses diffractive metagrating for direct measurement of specific target analytes, with enhanced sensitivity down to 770 femtomolar concentration, and without needing a spectrometer or source calibration. Sadatnajafi et al. (article number 2009419) show direct visualisation of ion implantation in a thin film (TiO2), based on analysing the brightfield optical images and plasmon resonance spectra generated by bimodal plasmonic color filters. Fernandez et al. (article number 2103103) develop an approach to developing novel designer glasses that is projected to become an optical platform for next-generation devices that aim for high-density integration and realisation of novel concepts. The target applications of such glasses include mid-infrared integrated devices and next-generation integrated quantum photonic devices, with applications in the life and environmental sciences. Yu et al. (article number 2106387) develop fully solution-processed transparent inorganic quantum-dot light-emitting diodes critical to realising transparent flexible optoelectronics. Jiang et al. (article number 2104259) develop a framework creating high-optical-frequency dielectric constant materials that could be used in simple homojunction organic solar cells. Shabbir et al. (article number 2105038) demonstrate the first ultrathin material in the form of tin monosulfide nanosheets can effectively absorb X-rays in the (200–600 eV) spectral region and then convert the energy into free electrical carriers through the photoelectric effect for high-sensitivity detection. The work opens up a new paradigm for ultrathin materials in high-sensitivity x-ray detection. Capon et al. (article number 2010713) develop a silk-based optical-fibre coating for producing bifunctional and dual-pH sensing and optical-coherence tomography imaging probes, and apply these to in vitro fertilisation. Lai et al. (article number 2105230) design a low-loss, energy-efficient, and reflection-free hybrid As2S3–Ge:SiO2 waveguide platform for on-chip simulated Brillouin scattering, with prospects of improving the performance of microwave photonic systems. A review by Daikuara et al. (article number 2105080) provides an overview of the established platforms for 3D-bioprinted skin constructs, especially 3D-printed cell-laden platforms for skin regeneration, discussing the further advances required to develop functional and transplantable 3D-printed skin structures with sufficient tissue restoration to improve clinical outcomes. Saraiva et al. (article number 2105488) demonstrate the development of silicon-based qubits for quantum computing. These silicon qubits operate at record-breaking temperatures of 1.5 K (15 times higher than superconducting or previous silicon qubits could operate). Mahmud et al., (article number 2009164) cover the dominant role in engineering mixed dimensional 2D–3D perovskite solar cells—with high efficiency and increased stability; and mapping out and understanding how key engineering parameters affect their future R&D technology with applications of real-world impact. Zhang et al., (article number 2103092) review fundamental principles and advances in 3D-printed electrodes for wearable batteries. A particular focus is on recent breakthroughs in printable functional inks and electrode surface chemistry and fabrication. Huang et al., (article number 2106020) describe the evolution and current status of Ca2+ sensors in tracing intra- and extra-cellular Ca2+, with a focus on the relevance of Ca2+ signaling to insulin secretion in the islet of Langerhans. Insights into Ca2+ sensors are anticipated to facilitate their advancement towards improved understanding of the pertinent molecular mechanisms underpinning cellular functions. Finally, Gupta et al., (article number 2109105) highlight recent advances in materials design using atomic layer deposition for energy applications. And Khan et al. (article number 2105259) highlight the important role of second harmonic generation in 2D materials for applications in a range of optical devices. These innovations show significant promise for tackling some of the most urgent biomedical challenges, by offering superior performance and functionality over conventional technologies, and overcoming or minimising existing limitations in design, engineering, and material versatility. We thank all of the authors for their contributions to this ANFF special issue, as well as the handling editor, Dr. Gaia Tomasello, for her contributions to highlighting the exciting Australian research supported by ANFF. Roey Elnathan gained his PhD in chemistry in 2012 at Tel Aviv University. At the University of South Australia he was a Research Fellow in nanobiotechnology (2012–15) and a Foundation Fellow in nanobiotechnology (2015–17). He is now a Senior Research Fellow (DECRA Fellow) in the Faculty of Pharmacy and Pharmaceutical Sciences at Monash University in Melbourne. His research expertise lies in engineered nano-bio cellular interfaces, especially in the fabrication and design of nanotopographies optimised for bioactive cargo delivery and in orchestrating fundamental cellular processes. Nicolas H. Voelcker gained his BSc at the University of Saarland (1993), his MSc at the RWTH Aachen (1995), and his PhD at the DWI Leibniz Institute (1999). He was a postdoctoral fellow at the Scripps Research Institute in California (2000?). At Flinders University in Adelaide he took up a lecturership (2001), an Associate Professorship (2006), and a full Professorship (2008). He was a Professor at the University of South Australia (2012–17) before becoming the Scientific Director of the Melbourne Centre for Nanofabrication, Professor at Monash University, and Science Leader at the Commonwealth Scientific and Industrial Research Organisation (CSIRO, Australia).