Patterning of metallic nanogaps with ultrasmall gap size on arbitrary substrates is of great importance for various applications in nanoelectronics, nanoplasmonics, and flexible optoelectronics. Common lithographic approaches suffer from limited resolution in defining ultrasmall nanogaps and restrictive available substrates for flexible and stretchable devices. In this work, a process portfolio to overcome the above limitations is proposed, enabling the fabrication of multiscale metallic nanogaps with reduced gap size on specific substrates for functional devices. The portfolio combines the recently developed sketch and peel lithography strategy, nanotransfer printing, and post‐mechanical assembly. Among the portfolio, the sketch and peel lithography strategy provides the unique capability to rapidly and reliably define multiscale adhesion‐free metallic nanostructures and nanogaps, which significantly facilitates the subsequent transfer printing process. Nanoplasmonic and nanoelectronic devices with ultrasmall nanogaps that are inaccessible with existing patterning approaches are fabricated to demonstrate the applicability of this fabrication strategy. The portfolio could also have potential for a variety of other applications in flexible and stretchable optics, electronics, and optoelectronics.

measures are primarily based on digital cryptographic signature or physical identification tag. [8][9][10] Digital cryptographic keys generated by pseudo-random mathematic functions need to be programmed into nonvolatile memory, accompanied with complicate tamper resilient devices to protect the keys from side-channel attacks. [11] Physical identification tags such as radiofrequency identification tags (RFID), [1,12] holograms, [13,14] graphical tags, [15] watermarks, [16] security inks, [17,18] barcode, [19][20][21] and chemical tag [9,22] have already been introduced to the consumer products for property protection. Nonetheless, these tags are made in deterministic processes, thus are vulnerable to clone attacks due to the low complexity and high predictability. More complex molecular tags could be adopted with an increase in cost, and can only be accessible in specialized laboratory. [23][24][25] To combat the rising tide of counterfeiting, physical unclonable function (PUF, or physical one-way function) has been introduced. [26,27] PUF is made from an indeterministic stochastic process, whose fingerprint-like response is difficult to predict upon external stimulus, thereby naturally immune to the clone attack. The sufficiently large complexity of PUF also renders it effective against brute force reverse engineering and tamper attack. [28] Conventional integrated circuit (IC) based PUFs typically utilize the inherent variations in the gate and wire time delays (e.g., arbiter PUF [29,30] and ring oscillator PUF [31] ) or local mismatches (e.g., SRAM PUF, [32] latch PUF, [33] flip-flop PUF [34] ) as the source of randomness. IC based PUF is convenient for on-chip integration owing to its CMOS compatibility, but is vulnerable to model building attack due to the relatively low complexity and large bit error rate. Emerging technologies with higher degree of complexity such as phase change memory, [35] interfacial magnetic anisotropy, [36] carbon nanotube field effect transistor, [37][38][39][40] memristor [41][42][43][44][45] are proposed with an exponential increase in cost and fabrication difficulty. Chemically synthesized PUFs can afford large encoding capacity, small footprint and low production cost by measuring readily detectable characteristics such as scattering speckle image, [26,[46][47][48] fingerprint like textures, [49][50][51] fluorescence or lasing [25,[52][53][54][55][56] surface enhanced Raman signature, [57][58][59][60] and unpredictable defects and patterns in 2D materials. [61,62] The complexity of chemical PUFs can easily be scaled Physical unclonable function (PUF) is promising for anticounterfeiting and security applications. In this paper, a PUF concept is demonstrated based on the stochastic generation of nanodot matrix via mechanical stripping of a gold film kirigami with arrayed nanoscale split-ring cuts. The random occurrence of nanofracture of metallic nanoconnection at split-ring parts results in unpredictable remaining (labeled as "1") or peeling-off (labeled as "0") of nanodots in ea...

The load sharing characteristics of the herringbone planetary transmission system are a key indicator for evaluating the bearing stability and reliability of each planet gear in the transmission system. The value of the load sharing coefficient is closely related to the manufacturing error and the assembly error in gear processing and assembly process. Therefore, it is indispensable to study the influence mechanism of these errors on the load sharing characteristics of the transmission system. Nevertheless, researches on the multi-coupling transmission error to the load sharing characteristics of herringbone planetary transmission system did not receive enough attention, but much of the single errors. Based on the centralized parameters theory and the Lagrange method, this research establishes a dynamic model for herringbone planetary transmission system and creatively proposes a study of multi-coupling error which consists of eccentric error, tooth profile error, stagger angle and assembly error. This work shows that the changing regulation of the load sharing characteristics with any one of the above errors is different. However, the load sharing characteristics become worse with the increase of multi-coupling error, in which the eccentric error plays a main role. Therefore, the error control should focus on eccentric error.

Face gear transmission is a kind of space-meshing mechanism that is mainly used in the field of aviation. Compared with traditional transmission, it has the advantages of stability, reliability, low noise, and strong carrying capacity. However, owing to its complex tooth surface, there are no means to accurately model the face gear. Likewise, research based on the geometry is difficult. Therefore, the tooth surface equation of the face gear is derived in this article based on the meshing theory. Based on the equations, the point cloud of the face gear tooth surface is calculated, the complex tooth surface is generated, and the face gear is accurately modeled. Moreover, taking tooth surface friction excitation into consideration, a multi-degree-of-freedom nonlinear dynamic model of face gear transmission system is established, using the adaptive variable step length Runge–Kutta method. As shown in the results, the bifurcation diagram, phase diagram, time history diagram, and Poincaré section diagram are combined to analyze the influence of tooth surface friction and meshing frequency on the dynamic characteristics of the system.