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Stretchable electronics have the unique capability of 3D (three dimensional) deformation, overcoming the brittleness of traditional inorganic electronics. However, during large deformations, different scale strains between the rigid and stretchable components lead to mismatch, causing interconnect failures. Therefore, the development of the rigidity‐programmable substrate with effective strain shielding capabilities has become a research hotspot. Furthermore, the exponential growth in electronic density presents challenges in the circuit design of stretchable electronics. The urgent need is to develop highly integrated stretchable electronic systems. In this study, a highly integrated stretchable pulse sensor with effective strain shielding capabilities using hybrid 3D printing technology is developed, which comprises electronic chips, a rigidity‐programmable substrate/encapsulation layer printed by using PSC (polydimethylsiloxane/silica‐nanoparticles composite)‐based ink, and LM (liquid metal)‐based 3D circuits. First, the PSC‐based ink is optimized to enhance the strain shielding effectiveness of the rigidity‐programmable substrate. Meanwhile, 3D printing parameters are optimized to achieve high printing precision with minimum line widths below 100 µm. The resulting stretchable pulse sensor demonstrated good mechanical and electrical stability under complex 3D deformations, including bending, twisting, and stretching. The PSC region strain of the sensor is only ≈2% when the global strain is up to ≈65%, which exhibited effective strain shielding capabilities. [ABSTRACT FROM AUTHOR]

Abstract Stretchable electronics have the unique capability of 3D (three dimensional) deformation, overcoming the brittleness of traditional inorganic electronics. However, during large deformations, different scale strains between the rigid and stretchable components lead to mismatch, causing interconnect failures. Therefore, the development of the rigidity‐programmable substrate with effective strain shielding capabilities has become a research hotspot. Furthermore, the exponential growth in electronic density presents challenges in the circuit design of stretchable electronics. The urgent need is to develop highly integrated stretchable electronic systems. In this study, a highly integrated stretchable pulse sensor with effective strain shielding capabilities using hybrid 3D printing technology is developed, which comprises electronic chips, a rigidity‐programmable substrate/encapsulation layer printed by using PSC (polydimethylsiloxane/silica‐nanoparticles composite)‐based ink, and LM (liquid metal)‐based 3D circuits. First, the PSC‐based ink is optimized to enhance the strain shielding effectiveness of the rigidity‐programmable substrate. Meanwhile, 3D printing parameters are optimized to achieve high printing precision with minimum line widths below 100 µm. The resulting stretchable pulse sensor demonstrated good mechanical and electrical stability under complex 3D deformations, including bending, twisting, and stretching. The PSC region strain of the sensor is only ≈2% when the global strain is up to ≈65%, which exhibited effective strain shielding capabilities.

Performance of microchannel heat exchangers is highly dependent on their geometry and shape. Hence, the structural design is as equally important as the material components. This paper expounds the development and applications of microchannel technology thereby proposing an optimal applicability on the microelectromechanical properties of heat exchange systems. [ABSTRACT FROM AUTHOR]

Abstract Unlike MOSFET technology, Field-Coupled Nanocomputing (FCN) structures are based upon a completely new computational paradigm. The basic computational element propagates the information through near-field interaction with neighboring elements. The potential of this principle is really promising because of the absence of current flow, leading to low power consumption. Here, we explore the in-plane NanoMagnetic Logic implementation. The analysis of complex circuits highlights the limitations due to their planar structure: mixing logic and interconnections on a single layer leads to an explosion of the circuit area. In this paper, we evaluate whether a 3D implementation of the structure can abruptly reduce the major limitation of the technology. We propose a solution by using a particular clock delivery method, named Virtual Clock. The analysis is carried out through micromagnetic and functional simulations on medium complexity architectures. The results obtained clearly highlight a large improvement in circuit area and power consumption. [ABSTRACT FROM AUTHOR]

Abstract Perpendicular NanoMagnet Logic (pNML) can be considered one of the most interesting emerging technology since it has unique features that cannot be naturally implemented with standard transistor technologies. Each device can act both as a memory and a logic circuit. Because of its intrinsic properties, this technology makes it possible to easily design 3D circuits. In this paper, we propose several complex architectures by exploiting the 3D integrability of the pNML technology. The presented circuits belong to different categories, covering both combinational and sequential circuits. Memory elements and logic circuits have been designed and simulated taking into account the technology constraints. As an absolute novelty, the first Finite State Machine based on pNML is also introduced. Highlights • Architectural exploration of perpendicular Nano Magnetic Logic (pNML) technology. • Design of combination and sequential circuits in pNML technology. • Design analysis of a pNML Random Access Memory, a 32-bit Ripple Carry Adder, a Programmable Logic Array and a FSM. • Performance analysis of the designed circuits. [ABSTRACT FROM AUTHOR]

The development of three-dimensional printed circuit boards requires research on new materials which can easily be deformed. Conducting pastes are well suited for deformation even after they are applied to the dielectric carrier. This paper deals with measurements of the electrical conductivity of these conducting pastes. Two different conductivity measurement techniques are explained and carried out. The resulting measurements give an overview of the conductivity of several measured samples.

Selective wetting of a gallium-based liquid metal on copper circuits is one of the ways to prepare liquid metal circuits. However, the complex fabrication processes of an adhesion layer between copper circuits (or patterns) and substrates were still inevitable, limiting scalable applications. Our work developed a facile way to directly prepare 2D and 3D liquid metal circuits by combining laser-induced selective metallization and selective wetting for the first time. The copper template was obtained on elastomers using laser-induced selective metallization, and high-resolution liquid metal circuits were fabricated by brushing Galinstan on the copper template in the alkali solution. The distribution of Cu element not only was on the top surface but also extended to the interior of the elastomer substrate. This revealed that the Cu layer prepared by laser-induced selective metallization is born to firmly embed into the substrate, which endowed the circuits with strong adhesion, reaching the highest 5B level. Moreover, the prepared liquid metal circuits (or patterns) had a typical layered structure. The liquid metal circuits exhibit good flexibility, stretchability, self-healing ability, and acid-alkaline resistance. Compared with the traditional methods of patterning liquid metals, fabricating liquid metal circuits based on laser-induced selective metallization has irreplaceable advantages, such as strong adhesion between circuits and substrate, fabricating 3D circuits, good acid-alkaline resistance, cost-effectiveness, maskless use, time savings, arbitrary design of patterns, and convenient operation, which endow this method with great application prospect.

A substrate that is designed to suppress parasitic modes while at the same time provides high-Q filtering capability is presented. High-density circuits require the integration of multiple functions in very limited space. More specifically, with the design of three-dimensional (3-D) circuits, parasitic effects caused by the excitation of surface waves result in a serious degradation of performance and impose limitations on circuit density and performance. Herein, an effort is presented to use advanced design concepts to enable embedded functionality within a substrate. The presented substrate geometries can easily be extended to 3-D to allow for the development of system-in-a-package which incorporates a high-Q filter bank to provide effective frequency selectivity. To demonstrate this concept, resonators and filters in LTCC are designed, fabricated and measured. Resonators in LTCC with unloaded Q up to 428 were measured. A narrow-band 2-pole filter is realized to show that a function of a relatively high-Q can be incorporated into the packaging. The 2.28% filter has an insertion loss of 1.7 dB due to the low loss nature of the design. Simulation and measurement of the structures are presented with good agreement achieved. [ABSTRACT FROM PUBLISHER]

In three-dimensional (3-D) circuits that employ multilevel metallization, a frequently encountered transmission line configuration is the embedded transmission line (ETL), which is essentially an offset stripline topology with two dielectrics. There is no closed-form expression available for either the characteristic impedance or effective dielectric constant, since the problem is analytically complex for an exact analysis. This work provides an approximate empirical formula for both the effective dielectric constant and the characteristic impedance, and compares them with full-wave simulations of the structure. A few percent error (typically, less than 3% for Z0, and 5% for εeff) is observed over a wide range of transmission line parameters [ABSTRACT FROM PUBLISHER]

The fluidity and high electrical conductivity of a liquid metal make it an excellent material for preparing flexible electronics. Here, we established a method utilizing a widespread laser-printing technique to manufacture 3D flexible electronics. Through digital constructing of liquid alloy-philic smooth toner on liquid alloy-phobic rough substrates, we have the liquid metal selectively adhered to the designed pattern. The liquid metal circuit can then be transferred to an uneven and deformable Ecoflex surface to form a 3D circuit. Computational fluid dynamics simulation was performed to interpret the printing mechanism of the liquid metal on a substrate with selected adhesion. Flexible electronics fabricated through this method reveal great performance and stability, opening up opportunities for office and home flexible electronics manufacture, especially for lighting, heating, and logistics. By making the full use of the laser printers, our method not only saves the cost and time in preparation but also identifies favorable prospects for the mature laser-printing industry to promote next-generation flexible electronics fabrication.

Printed circuits and electronics are widely implemented in a variety of emerging areas including solar power panel, wearable devices, screen display, etc. Recently, gallium‐based alloys become promising candidates in applications ranging from flexible electronics to efficient cooling due to its high conductivity, fluidity, and nontoxicity. However, the implementation of liquid metal printing is highly restricted to its adhesion with different substrates. The adhesiveness can be enhanced by promoting the oxidation such as intensive stirring, whereas the fluidity would be severely confined. Aiming to tackle the existing challenges, here the authors propose a facile liquid metal printed electronics method through spraying a customized superhydrophobic film upon the substrate and then forming desired patterns via selective adhesion of liquid metal. The required customization can be realized via removable mask or surface energy variation. The presented strategy demonstrates excellent substrate adaptability including glass, plastic, paper, carbon fiber composite, ceramic, etc. Besides, complex 3D circuits can be created upon curved surfaces of diversified geometries. Sprayed liquid metal can be easily recycled, which is beneficial to an environmental and sustainable production. This work suggests a potential direction for liquid metal circuit fabrication and may enlighten other studies to resolve liquid metal contamination, flow friction, etc. [ABSTRACT FROM AUTHOR]