Compact Micropatterned Chip Empowers Undisturbed and Programmable Drug Addition in High-Throughput Cell Screening.

Simultaneously adding multiple drugs and other chemical reagents to individual droplets at specific time points presents a significant challenge, particularly when dealing with tiny droplets in high-throughput screening applications. In this study, a micropatterned polymer chip is developed as a miniaturized platform for light-induced programmable drug addition in cell-based screening. This chip incorporates a porous superhydrophobic polymer film with atom transfer radical polymerization reactivity, facilitating the efficient grafting of azobenzene methacrylate, a photoconformationally changeable group, onto the hydrophilic regions of polymer matrix at targeted locations and with precise densities. By employing light irradiation, the cyclodextrin-azobenzene host-guest complexes formed on the polymer chip can switch from an "associated" to a "dissociated" state, granting precise photochemical control over the supramolecular coding system and its surface patterning ability. Significantly, the exceptional spatial and temporal control offered by these chemical transitions empowers to utilize digital light processing systems for simultaneous regulation and release of cyclodextrin-bearing drugs across numerous droplets containing suspended or adhered cells. This approach minimizes mechanical disruption while achieving precise control over the timing of addition, dosage, and integration varieties of released drugs in high-throughput screening, all programmable to meet specific requirements.

Liquid-in-liquid printing of 3D and mechanically tunable conductive hydrogels.

Conductive hydrogels require tunable mechanical properties, high conductivity and complicated 3D structures for advanced functionality in (bio)applications. Here, we report a straightforward strategy to construct 3D conductive hydrogels by programable printing of aqueous inks rich in poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) inside of oil. In this liquid-in-liquid printing method, assemblies of PEDOT:PSS colloidal particles originating from the aqueous phase and polydimethylsiloxane surfactants from the other form an elastic film at the liquid-liquid interface, allowing trapping of the hydrogel precursor inks in the designed 3D nonequilibrium shapes for subsequent gelation and/or chemical cross-linking. Conductivities up to 301 S m-1 are achieved for a low PEDOT:PSS content of 9 mg mL-1 in two interpenetrating hydrogel networks. The effortless printability enables us to tune the hydrogels' components and mechanical properties, thus facilitating the use of these conductive hydrogels as electromicrofluidic devices and to customize near-field communication (NFC) implantable biochips in the future.

Reactive Superhydrophobic Surfaces for Interlayer Electrical Connectivity in Three-dimensional Electronics.

This study describes the development of a new type of amine-reactive superhydrophobic (RSH) film that is facilely coated on various substrates using a single-step process, while the versatility of this RSH film offers a reliable solution for efficient formation of complex and robust interlayer electrical connectivity (IEC) in 3D electronic systems. The excellent spatial controllability of surface amine modification enables the generation of vertical circuits in situ, providing a distinct way to connect circuits located on different layers. Moreover, the inherent superhydrophobicity and porosity exhibit the required anti-fouling and breathability properties, making the RSH-based IEC well-suited for applications where exposure to environmental gas and liquid contaminants is likely. This approach provides another avenue towards the development of IEC in 3D flexible integrated electronics, opening up new possibilities for the advancement of this field.

Impact of Defects for AlN Single Crystal Thin Film by Metal Nitride Vapor Phase Epitaxy.

Herein, the defect-related properties of an AlN sample prepared based on the optimal process parameters by metal nitride vapor phase epitaxy (MNVPE) were investigated. The FWHM values of the (0002)/(101̅2) planes of the sample by MNVPE are 397/422 arcsec; the advantages of similar FWHM values of (0002) and (101̅2) planes will have a huge advantage over other preparation methods such as MOCVD. From the cross-sectional TEM images of the AlN sample, it is found that the fusion of a large number of a + c type dislocations occur at the interface of the low temperature buffer layer and the epitaxial layer, which affects the growth mode of the epitaxial layer. The lower FHWM value of the E 2(high) peak of the Raman spectrum, the lower the point defect concentration, which made the sample gain higher energy defect emission bands in the PL spectra and higher transmittance in the UV-vis transmission spectrum.

Structure and Optical Properties of AlN Crystals Grown by Metal Nitride Vapor Phase Epitaxy with Different V/III Ratios.

The epitaxial aluminum nitride (AlN) crystals were grown on c-plane sapphire using high-temperature metal nitride vapor phase epitaxy at the source materials' different molar flow ratios (V/III ratios). The effects of various V/III ratios on the surface morphology, crystalline quality, material straining, and optical properties of heteroepitaxial AlN thin films were studied using X-ray diffraction, scanning electron microscopy, Raman spectroscopy, and photoluminescence (PL). With the increase in the V/III ratio from 1473 to 7367, the substrate surface underwent changes that vary from whiskers to three-dimensional island structures, two-dimensional layered stack structures, and stacked sheet structures. Additionally, due to the presence of nanoscale pits on the substrate surface, almost all samples were tensile stressers. The PL spectra demonstrated the defect luminescence of the epitaxial films, indicating that nitrogen vacancies and oxygen impurities were the samples' main defects.

A Reactive Superhydrophobic Platform for Living Photolithography.

Superhydrophobic surfaces with regional functions have widespread applications in biotechnology, diagnostic applications, and micro-chemical synthesis and analysis. However, owing to their chemical inertness, superhydrophobic surfaces with chemical reactivity are difficult to achieve. Superhydrophobic surfaces that can be further modified with varied densities and expanded species of the functional moieties are not readily available. In this study, a single-step approach to achieve a reactive superhydrophobic surface is reported, on which chemical grafting of a library of molecules can be carried out through surface-initiated atom-transfer radical addition or surface-initiated atom-transfer radical polymerization. The excellent spatial and temporal controllability of these chemical processes under visible light enables us to take advantage of programmed liquid-crystal-display (LCD) or Digital Light Processing (DLP) photolithography systems to effortlessly regulate the location, density, and species of the functional molecules on the reactive superhydrophobic surface. The distinctive properties of this surface will provide new insight into intelligent superhydrophobic material development and practical applications, such as aqueous/oil microdroplets array, multi-anti-counterfeiting labels and integrated microfluidic reactors with enzymes for chemical logic learning.

Current Regulation and Property Study of Porous Anodic Alumina Films with a Periodic Pore Structure.

Porous anodic alumina (PAA) films with periodically modulated pore diameters are prepared by cyclic anodization of Al in a 0.6 M H3PO4 solution at room temperature. Studies have demonstrated that the oscillating current signals have an important effect on the structures of PAA films. Scanning electron microscopy (SEM) images of the PAA film show that when the positive triangle wave current signal is applied, with the increase in the maximum current value, PAA gradually exhibits a symmetrically modulated pore diameter structure, and part of the pores generates slub-like branches. When the maximum current value is 60 mA, the effect of modulation on the pore diameter is the most obvious and the UV reflectance spectrum shows the lowest reflectivity. A sawtooth wave current signal will cause the generation of a V-shaped structure at the junction of adjacent oxide layers. This work provides important guidance for regulating the structure of PAA by changing the current signal.

Electronic Structure and Ferromagnetism Modulation in Cu/Cu2O Interface: Impact of Interfacial Cu Vacancy and Its Diffusion.

Cu/Cu2O composite structures have been discovered to show sizable ferromagnetism (FM) with the potential applications in spintronic devices. To date, there is no consensus on the FM origin in Cu/Cu2O systems. Here, first principles calculations are performed on the interface structure to explore the microscopic mechanism of the FM. It is found that only the Cu vacancy (V(Cu)) adjacent to the outermost Cu2O layer induces a considerable magnetic moment, mostly contributed by 2p orbitals of the nearest-neighbor oxygen atom (O(NN)) with two dangling bonds and 3d orbitals of the Cu atoms bonding with the O(NN). Meanwhile, the charge transfer from Cu to Cu2O creates higher density of states at the Fermi level and subsequently leads to the spontaneous FM. Furthermore, the FM could be modulated by the amount of interfacial V(Cu), governed by the interfacial Cu diffusion with a moderate energy barrier (~1.2 eV). These findings provide insights into the FM mechanism and tuning the FM via interfacial cation diffusion in the Cu/Cu2O contact.

GaN as an interfacial passivation layer: tuning band offset and removing fermi level pinning for III-V MOS devices.

The use of an interfacial passivation layer is one important strategy for achieving a high quality interface between high-k and III-V materials integrated into high-mobility metal-oxide-semiconductor field-effect transistor (MOSFET) devices. Here, we propose gallium nitride (GaN) as the interfacial layer between III-V materials and hafnium oxide (HfO2). Utilizing first-principles calculations, we explore the structural and electronic properties of the GaN/HfO2 interface with respect to the interfacial oxygen contents. In the O-rich condition, an O8 interface (eight oxygen atoms at the interface, corresponding to 100% oxygen concentration) displays the most stability. By reducing the interfacial O concentration from 100 to 25%, we find that the interface formation energy increases; when sublayer oxygen vacancies exist, the interface becomes even less stable compared with O8. The band offset is also observed to be highly dependent on the interfacial oxygen concentration. Further analysis of the electronic structure shows that no interface states are present at the O8 interface. These findings indicate that the O8 interface serves as a promising candidate for high quality III-V MOS devices. Moreover, interfacial states are present when such interfacial oxygen is partially removed. The interface states, leading to Fermi level pinning, originate from unsaturated interfacial Ga atoms.