Plant sap analysis typically relies on destructive sampling and immediate freezing, limiting field deployment and longitudinal studies. We introduce a minimally invasive microfluidic device that extracts sap from the stem of Solanum lycopersicum and dries it in situ, enabling storage analogous to dried blood spots in humans. Using both artificial phytohormone mixtures and tomato sap, we assessed the stability of dried samples stored at room temperature for up to seven days and observed no substantial degradation of key phytohormones. Device performance was further validated in a paired sampling experiment, showing strong agreement with a conventional stem severing method for tZR and ABA quantification. These findings demonstrate that dried sap sampling via a microfluidic device provides a practical, field ready alternative to destructive methods, supporting repeated sampling from the same plant and enabling longitudinal metabolic monitoring.

Micro- and nanoscale patterning of conformal thin-film coatings on the exterior surfaces of complex three-dimensional (3D) structures is essential for emerging applications such as soft robotics, photonics, and functional 3D-printed MEMS devices. However, existing methods struggle to deliver high-resolution patterning on complex 3D structures and often suffer from poor thickness control, and inadequate surface conformity of the thin-film coatings. Here we present a robust approach for patterning of conformal thin-film coatings on complex 3D structures, including on sloped surfaces with angles up to 90°, with multiscale dimensions from 100 μm to 100 nm, and even down to the sub-30 nm scale when mask shrinkage techniques are used. This patterning approach utilizes a lithographically defined 3D Scaffold-Architected Lift-Off (SALO) mask in the lift-off process. It is agnostic to the used thin-film deposition process and enables even lift-off patterning of atomic layer deposited (ALD) conformal coatings, a task infeasible for conventional shadowing-based lift-off processes. Our approach opens opportunities for manufacturing complex 3D structures at the micro- and nanoscale by enabling lithographic patterning on the exterior surfaces of arbitrary 3D structures.

Continuous observation of molecular and cellular dynamics in vivo is critical for understanding disease progression and therapeutic response. Conventional approaches, such as imaging or endpoint assays, are limited by their discontinuous nature and the physiological stress they impose on animal models. Here, we present a minimally invasive millimetric implantable device (5 × 5 × 5 mm³) designed for fully autonomous, continuous in vivo fluorescence tracking. The device integrates a miniaturized optical system with low-power on-board electronics, enabling uninterrupted fluorescence recording in close proximity to the biological source. We validated the device by tracking sustained release and systemic clearance of fluorescein isothiocyanate in vivo over 30 h. We further demonstrated long-term utility by continuously tracking tumor-associated fluorescence in a subcutaneous glioma model for 2 weeks. These results present a compact, self-contained device enabling continuous longitudinal fluorescence sensing in animal models, providing a platform for investigating drug delivery, tumor development, and immunological processes in their native microenvironments.

Integrated optical microsystems are key to next-generation communication, sensing, and quantum technologies, with the potential to exceed the capabilities of conventional microelectronics. Such systems rely on precise control of light, but creating optimal 3D micro-optics is challenging for conventional microfabrication technologies. Multiphoton lithography (MPL) offers nanoscale 3D printing capabilities, while efforts to extend MPL to high-performance glasses typically involve harsh high-temperature or chemical postprocessing that is incompatible with integrated optical microsystems. To address this, we explore the use of hydrogen silsesquioxane (HSQ), an inorganic precursor, for MPL. We demonstrate postprocessing-free 3D printing of solid silica glass and self-forming glass nanogratings with nanoscale resolution. These advances enable the direct integration of glass micro-optics on photonic chips and optical fibers. We present functional 3D-printed glass optical devices, including on-chip ring resonators and photoluminescent sources, and fiber-tip refractive index sensors and polarization beam splitters, opening new avenues for high-performance optical microsystem integration.

Solid-state nanopores in ultrathin (<20 nm) membranes enable label-free single-molecule sensing, but their adoption as sensors is limited by the lack of scalable manufacturing methods that deliver nanopores with single-nanometer reproducibility. Self-limiting metal-assisted chemical etching (MACE) in silicon-on-insulator (SOI) membranes offers a parallel wet-chemical route for nanopore fabrication, yet prior demonstrations lacked a predictive design rule and required electron microscopy or electrical tests for confirming presence and number of pores. Here, we convert self-limiting MACE into a manufacturing-oriented workflow with optical process control to obtain and verify the formation of 4 nm nanopores in a scalable fashion. We decouple the deposition of 200 +/- 10 nm gold (Au) nanoparticles from etching, enabling independent optimization of the two steps. The nanoparticle size allows for particle-per-membrane counting by dark-field optical microscopy, so that deposition can be repeated when counts are below target. We then map etching behavior across Au nanoparticle diameter d (10-200 nm) and silicon (Si) device-layer thickness t (5-18 nm), finding that d/t >= 0.8 ratio predicts self-limiting MACE behavior, where pore diameter becomes independent of particle size. In this regime, 200 +/- 10 nm catalysts yield 4 +/- 1 nm pores, corresponding to a reduction of similar to 50 & times; in pore diameter and similar to 10 & times; in pore-diameter variability compared to the catalyst diameter and related variability. Successful through-membrane pore formation produces undercuts in the buried oxide (typically similar to 200-300 nm diameter) beneath each pore, which can be characterized for each membrane by bright-field microscopy and used as a proxy for the otherwise optically invisible 4 nm pores. Together, the predictive d/t framework and two-stage optical verification establish a scalable wet-chemical route to fabricate nanopores for biomolecular sensing and related nanofluidic devices.

3D printing at the macroscale has evolved from making plastic prototypes to the production of high-performance functional metal parts for industries such as medical and aerospace. By contrast, MEMS devices today are produced in large quantities using semiconductor manufacturing processes. However, the semiconductor manufacturing paradigm is not cost-effective for producing customized MEMS devices in small to medium volumes (tens to thousands of units per year), and related applications are difficult to address efficiently. 3D printing of functional MEMS devices could play an important role in filling this gap. Here, we discuss recent advances in 3D- printed functional MEMS, addressing the challenges of economical customization at smaller production volumes.

We present a fabrication process for 3D printing of glass sensors directly onto the end of optical fiber tips. Compared to conventional polymeric 3D-printed fiber-tip sensors, our method provides far superior chemical resistance and mechanical durability. We demonstrate the utility of our sensors by reliably measuring the refractive index of aggressive organic solvents - environments where polymer-based sensors are prone to swelling and deformation. This breakthrough opens new avenues for deploying robust glass sensors in demanding industrial settings, such as chemical processing plants and oil refineries, where precise and durable refractive index measurements are essential.

Microphysiological systems (MPS) are advanced in vitro platforms engineered to replicate in vivo conditions for studying human biology, disease mechanisms, and drug responses with greater physiological relevance. Fluorescence sensing is widely used as a functional readout in MPS due to its high sensitivity, selectivity, and stability. However, conventional fluorescence sensing systems often rely on bulky instrumentation with limited integration, which restricts continuous in situ monitoring, scalable high-throughput analysis, and spatially resolved investigation in multi-organ-on-a-chip models. To address these limitations, we present a highly miniaturized, fully integrated optical system with a 1 mm² footprint, enabling continuous in situ fluorescence monitoring of three-dimensional microtissues in close proximity. The system integrates microscale illumination and sensing units for fluorescence excitation and selective detection, an optical element for guided light propagation, and a microcage for mechanical confinement of microtissues. To demonstrate its capabilities, we integrated the miniaturized optical system with an MPS-relevant platform to monitor fluorescence signals in transgenic mouse pancreatic islets expressing genetically encoded calcium indicators. The integrated platform enables real-time, continuous monitoring of islet responses to potassium chloride stimulation and tracking of calcium oscillations for over two hours, providing valuable information about the functional status of the pancreatic islets. Our work enhances the analytical capabilities of MPS through the integration of miniaturized on-chip quantitative assessment tools, enabling precise, in situ, and continuous monitoring of biological activities in close proximity.

Single-molecule trapping and analysis are critical in understanding biomolecular processes at an unprecedented resolution. Traditional nanopore systems often face limitations in scalability and integration with electronic components, which complicates their use in compact, high-density applications. Addressing these challenges, we introduce a novel on-chip nanopore array system integrated with a silver (Ag) electrode and self-aligned femtolitersized cavities, representing an innovative approach for electronic single-molecule trapping. Our design utilizes a wafer-scale fabrication process with a buried electrode architecture, enabling the scalable production of high-density nanopore arrays without the need for through-wafer etching. Successful DNA translocation measurements demonstrate the system's potential as a versatile platform for single-molecule trapping and reaction studies.

Controlled breakdown has emerged as an effective method for fabricating solid-state nanopores in thin suspended dielectric membranes for various biomolecular sensing applications. On an unpatterned membrane, the site of nanopore formation by controlled breakdown is random. Nanopore formation on a specific site on the membrane has previously been realized using local thinning of the membrane by lithographic processes or laser-assisted photothermal etching under immersion in an aqueous salt solution. However, these approaches require elaborate and expensive cleanroom-based lithography processes or involve intricate procedures using custom-made equipment. Here, we present a rapid cleanroom-free approach using single pulse femtosecond laser exposures of 50 nm thick silicon nitride membranes in air to localize the site of nanopore formation by subsequent controlled breakdown to an area less than 500 nm in diameter on the membrane. The precise positioning of the nanopores on the membrane could be produced both using laser exposure powers which caused significant thinning of the silicon nitride membrane (up to 60% of the original thickness locally), as well as at laser powers which caused no visible modification of the membrane at all. We show that nanopores made using our approach can work as single-molecule sensors by performing dsDNA translocation experiments. Due to the applicability of femtosecond laser processing to a wide range of membrane materials, we expect our approach to simplify the fabrication of localized nanopores by controlled breakdown in a variety of thin film material stacks, thereby enabling more sophisticated nanopore sensors.