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Abstract Versatile printing of polymers, metals, and composites always calls for simple, economic approaches. Here we present an approach to three-dimensional (3D) printing of polymeric, metallic, and composite materials at room conditions, based on the polymeric vapor-induced phase separation (VIPS) process. During VIPS 3D printing (VIPS-3DP), a dissolved polymer-based ink is deposited in an environment where nebulized non-solvent is present, inducing the low-volatility solvent to be extracted from the filament in a controllable manner due to its higher chemical affinity with the non-solvent used. The polymeric phase is hardened in situ as a result of the induced phase separation process. The low volatility of the solvent enables its reclamation after the printing process, significantly reducing its environmental footprint. We first demonstrate the use of VIPS-3DP for polymer printing, showcasing its potential in printing intricate structures. We further extend VIPS-3DP to the deposition of polymer-based metallic inks or composite powder-laden polymeric inks, which become metallic parts or composites after a thermal cycle is applied. Furthermore, spatially tunable porous structures and functionally graded parts are printed by using the printing path to set the inter-filament porosity as well as an inorganic space-holder as an intra-filament porogen. 

This paper presents a novel engineered substrate enabled by patterned Permalloy (Ni 80 Fe 20 , Py) thin films for the development of miniaturized antenna with improved bandwidth. The perspective substrate is implemented with multiple layers of 100 nm thick Py thin film patterns embedded on arbitrary microwave substrate, and each Py layer consists of an array of Py patterns with a dimension of 15μm×40μm and 5 μm gaps among them to suppress the magnetic loss. An equivalent permeability of 2.398 is achieved for engineered substrate embedding with 10 layers of Py thin films. A simple patch antenna has been implemented on the engineered substrate to demonstrate the efficacy of designing miniaturized antenna with improved bandwidth, compared to antenna on regular substrate, results show that the developed antenna on engineered substrate has a size reduction of 47.3% and an improved bandwidth of 49.6%. 

Engineered substrate enabled by Permalloy (Ni 80 Fe 20 , Py) thin films has been well developed for RF applications with high and tunable permeability and moderate loss. A full investigation on the characteristics of the engineered substrate is presented in this paper. The loss and equivalent permeability generated by the Py patterns are characterized through a microstrip line model. Multiple factors of Py patterns are taken into consideration to define the performance of the engineered substrate, including filling density, thickness, dimensions, and locations. The analytical results give a detailed guideline for the design of engineered substrate. 

This paper presents a methodology in the development of miniaturized and electrically tunable RF and Microwave passives with engineered substrate which has high and electrically tunable effective permeability. The perspective substrate is implemented with multiple layers of 100 nm thick Permalloy (Py) thin film patterns embedded on Silicon substrate, and each Py layer consists of an array of 15μm×40μm Py patterns with 5 μm gaps among them to suppress the magnetic loss. The effective permeability of the single layer and ten layers of Py enabled substrate is tunable by the static magnetic field produced from the applied DC current providing a tunability of 3.3% and 18.8%, respectively. Passives are developed on the proposed engineered substrate with a single layer embedded Py to demonstrate the efficacy of the engineered substrate on the design of arbitrary tunable components. Results show that the developed transmission line-based phase shifter provides continuous 90° phase shift from 0.956 GHz to 1.01GHz, and the center frequency of the bandpass filter shifts from 2.42GHz to 2.56GHz continuously.