Human eyes possess exceptional image sensing characteristics such as spectacularly wide field of view (FOV), high resolution and sensitivity with low aberration. Biomimetic eyes with the same superior characteristics are highly desirable in many technological applications. However, the spherical nature of biological eyes, particularly the core component of retina, poses an enormous challenge for fabrication of biomimetic eyes. Herein, we demonstrate a unique biomimetic electrochemical eye using a hemispherical retina made of high-density array of nanowires mimicking photoreceptors on a real retina. The device design has a high degree of structural similarity to a real human eye with potency to achieve a high imaging resolution when individual nanowires are electrically addressed. Meanwhile, image sensing function of our biomimetic eye device is also demonstrated. The work here may lead to a new generation of photosensing and imaging devices based on a bioinspired design that can benefit a wide spectrum of technological applications.

Engineering layer-layer interactions provides a powerful way to realize novel and designable quantum phenomena in van der Waals heterostructures 1-16 . Interlayer electron-electron interactions, for example, have enabled fascinating physics that is di cult to achieve in a single material, such as the Hofstadter's butterfly in graphene/boron nitride (hBN) heterostructures [5][6][7][8][9][10] . In addition to electron-electron interactions, interlayer electron-phonon interactions allow for further control of the physical properties of van der Waals heterostructures. Here we report an interlayer electron-phonon interaction in WSe 2 /hBN heterostructures, where optically silent hBN phonons emerge in Raman spectra with strong intensities through resonant coupling to WSe 2 electronic transitions. Excitation spectroscopy reveals the double-resonance nature of such enhancement, and identifies the two resonant states to be the A exciton transition of monolayer WSe 2 and a new hybrid state present only in WSe 2 /hBN heterostructures. The observation of an interlayer electron-phonon interaction could open up new ways to engineer electrons and phonons for device applications.Van der Waals heterostructures of atomically thin twodimensional (2D) crystals are a new class of material in which novel quantum phenomena can emerge from layer-layer interactions [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] . For example, electron-electron interactions between adjacent 2D layers can give rise to a variety of fascinating physical behaviours: the interlayer moiré potential between the graphene and hBN layers leads to mini-Dirac cones and the Hofstadter's butterfly pattern in graphene/hBN heterostructures 5-10 ; electronic couplings between MoS 2 and MoS 2 layers lead to a direct-to indirect-bandgap transition in bilayer MoS 2 (refs 11,12); and Coulomb interactions between MoSe 2 and WSe 2 layers lead to interlayer exciton states in MoSe 2 /WSe 2 heterostructures 13,14 . Similar to electron-electron interactions, electron-phonon interactions also play a key role in a wide range of phenomena in condensed matter physics: the electron-phonon coupling sets the intrinsic limit of electron mobility 17 , dominates the ultrafast carrier dynamics 18 , leads to the Peierls instability 19 , and enables the formation of Cooper pairs 20 . Exploiting interactions between electrons in one layered material and phonons in an adjacent material could enable new ways to control electron-phonon coupling and realize novel quantum behaviour that has not previously been possible. For example, it has been recently shown that electrons in monolayer FeSe can couple strongly with phonons in the adjacent SrTiO 3 substrate, which may play an important role in the anomalously high critical temperature for superconductivity in the system 21,22 . However, the unusual interlayer electron-phonon interactions in the van der Waals heterostructures have been little explored so far, although there have been indications that interlayer interactions between graphene ...

Wearable and portable devices contribute to a rapidly growing emerging market for electronics and can find wide applications for wireless communications, multifunctional entertainments, personal healthcare monitoring, etc. [1][2][3][4][5] Typically, wearable devices with attractive attributes such as flexibility, long cruising time, and operation safety are highly desirable. [6][7][8][9][10][11] Recent advances in fields of power generation devices enable sustainable energy harvesting from the environment, such as solar energy, mechanical vibrations and frictions, biofluid and thermal energy from human body, and converted into electricity without external power sources, which introduces the concept of "self-powered" systems. [12][13][14][15][16][17] To realize continuous operation of the entire self-powered devices without interruption from surrounding conditions variation, such as insufficient solar illumination, fully integrated self-powered systems that consist of energy harvesting/conversion devices (e.g., solar cells, nanogenerators, biofuel cells), energy storage devices as intermediate energy storage units (e.g., rechargeable batteries, supercapacitors) and functional devices (e.g., sensors, transistors, biomedical implants) are highly desirable. [18] Planar supercapacitors with interdigitated electrodes constructed on single substrate emerged as one of the highly competitive energy storage devices to complement/replace batteries, offering merits of high power density, separator-free architectures for device miniaturization, and favorable operational safety without using flammable electrolytes. [19][20][21][22] Especially for integration with energy harvesting devices dealing with highly volatile energy input, particularly in wearable applications, supercapacitors possess an appealing capability to accommodate fast and high charging current fluctuation. [23][24][25][26] Although self-sufficient energy modules (e.g., photovoltaic-batteries, nanogenerator-supercapacitors) and selfpowered sensors (e.g., nanogenerator-sensors, battery-sensors) have been reported previously, [12,23,[26][27][28][29][30][31][32] to our best knowledge, demonstration of a fully integrated self-powered sensor system on flexible substrate implemented via additive printable strategy is rarely achieved, mainly due to the challenges on fabrication procedures compatibility and system integration of different device components.Wearable and portable devices with desirable flexibility, operational safety, and long cruising time, are in urgent demand for applications in wireless communications, multifunctional entertainments, personal healthcare monitoring, etc. Herein, a monolithically integrated self-powered smart sensor system with printed interconnects, printed gas sensor for ethanol and acetone detection, and printable supercapacitors and embedded solar cells as energy sources, is successfully demonstrated in a wearable wristband fashion by utilizing inkjet printing as a proof-of-concept. In such a "wearable wristband", the harvested so...