Power-integrated, wireless neural recording systems on the cranium using a direct printing method for deep-brain analysis.

Conventional power-integrated wireless neural recording devices suffer from bulky, rigid batteries in head-mounted configurations, hindering the precise interpretation of the subject's natural behaviors. These power sources also pose risks of material leakage and overheating. We present the direct printing of a power-integrated wireless neural recording system that seamlessly conforms to the cranium. A quasi-solid-state Zn-ion microbattery was 3D-printed as a built-in power source geometrically synchronized to the shape of a mouse skull. Soft deep-brain neural probes, interconnections, and auxiliary electronics were also printed using liquid metals on the cranium with high resolutions. In vivo studies using mice demonstrated the reliability and biocompatibility of this wireless neural recording system, enabling the monitoring of neural activities across extensive brain regions without notable heat generation. This all-printed neural interface system revolutionizes brain research, providing bio-conformable, customizable configurations for improved data quality and naturalistic experimentation.

Use of the Relative Citation Ratio in Conjunction With H-Index to Promote Equity in Academic Orthopaedics.

INTRODUCTION: Quantification of a researcher's productivity relies on objective bibliometric measurements, such as the Hirsch index (h-index). However, h-index is not field and time-normalized and possesses bias against newer researchers. Our study is the first to compare the relative citation ratio (RCR), a new article-level metric developed by the National Institutes of Health, with h-index in academic orthopaedics. METHODS: Academic orthopaedic programs in the United States were identified using the 2022 Fellowship and Residency Electronic Interactive Database. Available demographic and training data for surgeons were collected. RCR was calculated using the National Institutes of Health iCite tool, and h-index was calculated using Scopus. RESULTS: Two thousand eight hundred twelve academic orthopaedic surgeons were identified from 131 residency programs. H-index, weighted RCR (w-RCR), and mean RCR (m-RCR) all significantly differed by faculty rank and career duration. However, while h-index and w-RCR varied between sexes (P < 0.001), m-RCR did not (P = 0.066), despite men having a longer career duration (P < 0.001). DISCUSSION: We propose that m-RCR be used in conjunction with w-RCR or h-index to promote a fairer, comprehensive depiction of an orthopaedic surgeon's academic effect and productivity. Use of m-RCR may reduce the historic bias against women and younger surgeons in orthopaedics, which has implications in employment, promotion, and tenure.

Local zinc treatment enhances fracture callus properties in diabetic rats.

The effects of locally applied zinc chloride (ZnCl2 ) on early and late-stage parameters of fracture healing were evaluated in a diabetic rat model. Type 1 Diabetes has been shown to negatively impact mechanical parameters of bone as well as biologic markers associated with bone healing. Zinc treatments have been shown to reverse those outcomes in tests of nondiabetic and diabetic animals. This study is the first to assess the efficacy of a noncarrier mediated ZnCl2 on bony healing in diabetic animals. This is a promising basic science approach which may lead to benefits for diabetic patients in the future. Treatment and healing were assessed through quantification of callus zinc, radiographic scoring, microcomputed tomography (µCT), histomorphometry, and mechanical testing. Local ZnCl2 treatment increased callus zinc levels at 1 and 3 days after fracture (p ≤ 0.025). Femur fractures treated with ZnCl2 showed increased mechanical properties after 4 and 6 weeks of healing. Histomorphometry of the ZnCl2 -treated fractures found increased callus cartilage area at Day 7 (p = 0.033) and increased callus bone area at Day 10 (p = 0.038). In contrast, callus cartilage area was decreased (p < 0.01) after 14 days in the ZnCl2 -treated rats. µCT analysis showed increased bone volume in the fracture callus of ZnCl2 -treated rats at 6 weeks (p = 0.0012) with an associated increase in the proportion of µCT voxel axial projections (Z-rays) spanning the fracture site. The results suggest that local ZnCl2 administration improves callus chondrogenesis leading to greater callus bone formation and improved fracture healing in diabetic rats.

Cellulose Nanofiber/Carbon Nanotube-Based Bicontinuous Ion/Electron Conduction Networks for High-Performance Aqueous Zn-Ion Batteries.

Despite their potential as a next-generation alternative to current state-of-the-art lithium (Li)-ion batteries, rechargeable aqueous zinc (Zn)-ion batteries still lag in practical use due to their low energy density, sluggish redox kinetics, and limited cyclability. In sharp contrast to previous studies that have mostly focused on materials development, herein, a new electrode architecture strategy based on a 3D bicontinuous heterofibrous network scaffold (HNS) is presented. The HNS is an intermingled nanofibrous mixture composed of single-walled carbon nanotubes (SWCNTs, for electron-conduction channels) and hydrophilic cellulose nanofibers (CNFs, for electrolyte accessibility). As proof-of-concept for the HNS electrode, manganese dioxide (MnO2 ) particles, one of the representative Zn-ion cathode active materials, are chosen. The HNS allows uniform dispersion of MnO2 particles and constructs bicontinuous electron/ion conduction pathways over the entire HNS electrode (containing no metallic foil current collectors), thereby facilitating the redox kinetics (in particular, the intercalation/deintercalation of Zn2+ ions) of MnO2 particles. Driven by these advantageous effects, the HNS electrode enables substantial improvements in the rate capability, cyclability (without structural disruption and aggregation of MnO2 ), and electrode sheet-based energy (91 Wh kgelectrode -1 )/power (1848 W kgelectrode -1 ) densities, which lie far beyond those achievable with conventional Zn-ion battery technologies.

Ultrahigh areal number density solid-state on-chip microsupercapacitors via electrohydrodynamic jet printing.

Microsupercapacitors (MSCs) have garnered considerable attention as a promising power source for microelectronics and miniaturized portable/wearable devices. However, their practical application has been hindered by the manufacturing complexity and dimensional limits. Here, we develop a new class of ultrahigh areal number density solid-state MSCs (UHD SS-MSCs) on a chip via electrohydrodynamic (EHD) jet printing. This is, to the best of our knowledge, the first study to exploit EHD jet printing in the MSCs. The activated carbon-based electrode inks are EHD jet-printed, creating interdigitated electrodes with fine feature sizes. Subsequently, a drying-free, ultraviolet-cured solid-state gel electrolyte is introduced to ensure electrochemical isolation between the SS-MSCs, enabling dense SS-MSC integration with on-demand (in-series/in-parallel) cell connection on a chip. The resulting on-chip UHD SS-MSCs exhibit exceptional areal number density [36 unit cells integrated on a chip (area = 8.0 mm × 8.2 mm), 54.9 cells cm-2] and areal operating voltage (65.9 V cm-2).

A single-ion conducting covalent organic framework for aqueous rechargeable Zn-ion batteries.

Despite their potential as promising alternatives to current state-of-the-art lithium-ion batteries, aqueous rechargeable Zn-ion batteries are still far away from practical applications. Here, we present a new class of single-ion conducting electrolytes based on a zinc sulfonated covalent organic framework (TpPa-SO3Zn0.5) to address this challenging issue. TpPa-SO3Zn0.5 is synthesised to exhibit single Zn2+ conduction behaviour via its delocalised sulfonates that are covalently tethered to directional pores and achieve structural robustness by its ß-ketoenamine linkages. Driven by these structural and physicochemical features, TpPa-SO3Zn0.5 improves the redox reliability of the Zn metal anode and acts as an ionomeric buffer layer for stabilising the MnO2 cathode. Such improvements in the TpPa-SO3Zn0.5-electrode interfaces, along with the ion transport phenomena, enable aqueous Zn-MnO2 batteries to exhibit long-term cyclability, demonstrating the viability of COF-mediated electrolytes for Zn-ion batteries.

Printing of wirelessly rechargeable solid-state supercapacitors for soft, smart contact lenses with continuous operations.

Recent advances in smart contact lenses are essential to the realization of medical applications and vision imaging for augmented reality through wireless communication systems. However, previous research on smart contact lenses has been driven by a wired system or wireless power transfer with temporal and spatial restrictions, which can limit their continuous use and require energy storage devices. Also, the rigidity, heat, and large sizes of conventional batteries are not suitable for the soft, smart contact lens. Here, we describe a human pilot trial of a soft, smart contact lens with a wirelessly rechargeable, solid-state supercapacitor for continuous operation. After printing the supercapacitor, all device components (antenna, rectifier, and light-emitting diode) are fully integrated with stretchable structures for this soft lens without obstructing vision. The good reliability against thermal and electromagnetic radiations and the results of the in vivo tests provide the substantial promise of future smart contact lenses.