Multifunctional Hyperbolic Nanogroove Metasurface for Submolecular Detection

Metasurface serves as a promising plasmonic sensing platform for engineering the enhanced light–matter interactions. Here, a hyperbolic metasurface with the nanogroove structure in the subwavelength scale is designed. This metasurface is able to modify the wavefront and wavelength of surface plasmon wave with the variation of the nanogroove width or periodicity. At the specific optical frequency, surface plasmon polaritons are tightly confined and propagated with a diffraction‐free feature due to the epsilon‐near‐zero effect. Most importantly, the groove hyperbolic metasurface can enhance the plasmonic sensing with an ultrahigh phase sensitivity of 30 373 deg RIU^?1 and Goos–Hänchen shift sensitivity of 10.134 mm RIU^?1. The detection resolution for refractive index change of glycerol solution is achieved as 10^?8 RIU based on the phase measurement. The detection limit of bovine serum albumin (BSA) molecule is measured as low as 0.1 × 10^?18m (1 × 10^?19 mol L^?1), which corresponds to a submolecular detection level (0.13 BSA mm^?2). As for low‐weight biotin molecule, the detection limit is estimated below 1 × 10^?15m (1 × 10^?15 mol L^?1, 1300 biotin mm^?2). This enhanced plasmonic sensing performance is two orders of magnitude higher than those with current state‐of‐art plasmonic metamaterials and metasurfaces.     

Cell Behavior within Nanogrooved Sandwich Culture Systems

Grooved topography and inherent cell contact guidance has shown promising results regarding cell proliferation, morphology, and lineage‐specific differentiation. Yet these approaches are limited to 2D applications. Sandwich‐culture conditions are developed to bridge the gap between 2D and 3D culture, enabling both ventral and dorsal cell surface stimulation. The effect of grooved surface topography is accessed on cell orientation and elongation in a highly controlled manner, with simultaneous and independent stimuli on two cell sides. Nanogrooved and non‐nanogrooved substrates are assembled into quasi‐3D systems with variable relative orientations. A plethora of sandwich‐culture conditions are created by seeding cells on lower, upper, or both substrates. Software image analysis demonstrates that F‐actin of cells acquires the orientation of the substrate on which cells are initially seeded, independently from the orientation of the second top substrate. Contrasting cell morphologies are observed, with a higher elongation for nanogrooved 2D substrates than nanogrooved sandwich‐culture conditions. Correlated with an increased pFAK activity and vinculin staining for sandwich‐culture conditions, these results point to an enhanced cell surface stimulation versus control conditions. The pivotal role of initial cell‐biomaterial contact on cellular alignment is highlighted, providing important insights for tissue engineering strategies aiming to guide cellular response through mechanotransduction approaches.     

Polymer‐Based Organic Field‐Effect Transistors with Active Layers Aligned by Highly Hydrophobic Nanogrooved Surfaces

In this study, polymer‐based organic field‐effect transistors (OFETs) that exhibit alignment‐induced mobility enhancement, very small device‐to‐device variation, and high operational stability are successfully fabricated by a simple coating method of semiconductor solutions on highly hydrophobic nanogrooved surfaces. The highly hydrophobic nanogrooved surfaces (water contact angle >110°) are effective at inducing unidirectional alignment of polymer backbone structures with edge‐on orientation and are advantageous for realizing high operational stability because of their water‐repellent nature. The dewetting of the semiconductor solution is a critical problem in the thin film formation on highly hydrophobic surfaces. Dewetting during spin coating is suppressed by surrounding the hydrophobic regions with hydrophilic ones under appropriate designs. For the OFET array with an aligned terrace‐phase active layer of poly(2,5‐bis(3‐hexadecylthiophene‐2‐yl)thieno[3,2‐b]thiophene), the hole mobility in the saturation regime of 30 OFETs with channel current direction parallel to the nanogrooves is 0.513 ± 0.018 cm² V^?1 s^?1, which is approximately double that of the OFETs without nanogrooves, and the intrinsic operational stability is comparable to the operational stability of amorphous‐silicon field‐effect transistors. In other words, alignment‐induced mobility enhancement and high operational stability are successfully achieved with very small device‐to‐device variation. This coating method should be a promising means of fabricating high‐performance OFETs.     

基于纳米划痕仪的单晶锗纳米沟槽加工实验研究

为了提高纳米锗器件的制造精度,使用纳米划痕仪对单晶锗进行纳米沟槽刻划加工实验,采用扫描电子显微镜对沟槽形貌进行观察,并通过三维白光干涉表面形貌仪测量其三维形貌尺寸,研究了切削速度、施加的垂直载荷及刻划次数对单晶锗纳米沟槽形貌的影响。建立了垂直载荷和刻划次数与沟槽深度及宽度的线性拟合曲线和幂函数拟合曲线,并进行分析。结果表明,单晶锗纳米沟槽的宽度和深度随切削速度的变化非常小,随着垂直载荷的增大,刻划次数的增多而逐渐增大。曲线的拟合度很高,能够对制造纳米沟槽的深度和宽度进行较为准确的预测,从而可以降低工件表面粗糙度,提高工件表面质量。