Regardless of the technology, additive or subtractive, the miniaturization trend is constantly pushing for smaller resolutions. The rise of global challenges in material availability, fabrication in three dimensions (3D), design flexibility and rapid prototyping have pushed additive manufacturing (AM) into the spotlight. Addressing the miniaturization trend, AM has already successfully answered the challenges for microscale 3D fabrication. However, fabricating nano-resolution still presents a challenge. In this review, we will present some of the most reported AM-based technologies capable of nanoscale 3D fabrication addressing resolutions of ≤ 500 nm. The focus is placed on Electrohydrodynamic (EHD) printing (also known as e-jet printing), as EHD printing seems to have the best trade-off when it comes to technique complexity, achievable resolutions, material diversity and potential to scale-up throughput. An overview of the smallest achieved resolutions as well as the most unique use cases and demonstrated applications will be addressed in this work.

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Our recent development of a wireless humidity sensor system embedded in incontinence products enables new sensor applications to diagnose and supervise geriatric diseases (i.e., age-related diabetes mellitus type II). The measurement of glucose in urine, so-called glucosuria, is an early indicator for an incipient diabetes mellitus disease, whose symptoms are often age-related but misjudged. In this paper, an incontinence glucose sensor is printed with biocompatible ink and Prussian blue as an electron mediator on foil and functionalized with immobilized glucose oxidase. Inkjet printing of multiple layers of Nafion prevents large interference substances from diffusing into the measuring electrode and allows precise adjustment of the linear working range, which is significantly different from blood glucose measurement. Performance tests show the potential to detect minimum glucose values and store the sensor over a prolonged period at room temperature. The printed glucose sensor can be embedded into the absorber material of incontinence products, where capillary forces transport the urine analyte to the detection area. An attached readout module with an integrated potentiostat measures the glucose concentration in urine, which is transmitted wirelessly with incontinence events and stored in a cloud service for further analysis by medical staff and care workers.