Research Highlight

High-voltage Aqueous Mg-ion Battery Facilitated by Water-in-salt Electrolyte

Although widely used in our daily life, lithium (Li) -ion batteries fall short because the materials used are often scarce, toxic, and expensive. They also have safety issue in operation due to their organic based electrolytes. Beyond lithium-ion batteries, a low-cost magnesium (Mg) metal anode based aqueous Mg-ion battery has been developed first time by Professor Dennis Leung’s research team in the HKU Department of Mechanical Engineering. As Mg is the 5th most abundant metal element in the earth’s crust (three orders of magnitude more than Li), the advantages of low cost and non-toxicity make Mg a desirable alternative to Li as the anode material. The proposed battery shows a high discharge plateau of 2.4-2.0 V and an excellent rechargeability for over 700 stable cycles. This high operation voltage exceeds the counterpart of other multivalent-ion batteries, including zinc (Zn) metal and aluminum (Al) metal batteries. The mechanism behind was also revealed, where a conductive metallic oxide layer was facilitated by the chloride (Cl-) ions inside the water-in-salt electrolyte, providing ionic pathways for rechargeable battery operations. The team hopes that the chemical insights obtained in this work could inspire further optimization and bring attention to the overlooked development of rechargeable aqueous Mg metal batteries. This work uncovers the once dismissed possibility of aqueous Mg metal batteries and opens a new avenue in the field of post-lithium-ion batteries. Other project team members are Dr. Wending Pan (Research Assistant Professor) and Miss Sarah Leong (PhD student).

High-speed Laser-scanning Biological Microscopy using FACED

Laser scanning is used in advanced biological microscopy to deliver superior imaging contrast, resolution and sensitivity. However, it is challenging to scale up the scanning speed required for interrogating a large and heterogeneous population of biological specimens or capturing highly dynamic biological processes at high spatiotemporal resolution. Bypassing the speed limitation of traditional mechanical methods, free-space angular-chirp-enhanced delay (FACED) is an all-optical, passive and reconfigurable laser-scanning approach that has been successfully applied in different microscopy modalities at an ultrafast line-scan rate of 1-80 MHz. Optimal FACED imaging performance requires optimized experimental design and implementation to enable specific high-speed applications. In this protocol, we aim to disseminate information allowing FACED to be applied to a broader range of imaging modalities. We provide (i) a comprehensive guide and design specifications for the FACED hardware; (ii) step-by-step optical implementations of the FACED module including the key custom components; and (iii) the overall image acquisition and reconstruction pipeline. We illustrate two practical imaging configurations: multimodal FACED imaging flow cytometry (bright-field, fluorescence and second-harmonic generation) and kHz 2D two-photon fluorescence microscopy. Users with basic experience in optical microscope operation and software engineering should be able to complete the setup of the FACED imaging hardware and software in ~2-3 months.

Biofilm Inhibition in Oral Pathogens by Nanodiamonds​

Complex microbial communities, e.g., biofilms residing in our oral cavity, have recognized clinical significance, as they are typically the main cause for infections. Diamond nanoparticles, namely, nanodiamonds (NDs) have been demonstrated to work as an effective antibacterial agent against planktonic cells (free-floating state) due to their many promising physico-chemical properties. However, little is known about the behaviors of NDs against biofilms (sessile state).

Soft Robotic Manipulator for Intra-operative MRI-guided Transoral Laser Microsurgery

Magnetic resonance (MR) imaging (MRI) provides compelling features for the guidance of interventional procedures, including high-contrast soft tissue imaging, detailed visualization of physiological changes, and thermometry. Laser-based tumor ablation stands to benefit greatly from MRI guidance because 3D resection margins alongside thermal distributions can be evaluated in real time to protect critical structures while ensuring adequate resection margins. However, few studies have investigated the use of projection-based lasers like those for transoral laser microsurgery, potentially because dexterous laser steering is required at the ablation site, raising substantial challenges in the confined MRI bore and its strong magnetic field. Here, we propose an MR-safe soft robotic system for MRI-guided transoral laser microsurgery. Owing to its miniature size (Ø12 × 100 mm), inherent compliance, and five degrees of freedom, the soft robot ensures zero electromagnetic interference with MRI and enables safe and dexterous operation within the confined oral and pharyngeal cavities. The laser manipulator is rapidly fabricated with hybrid soft and hard structures and is powered by microvolume (<0.004 milliter) fluid flow to enable laser steering with enhanced stiffness and lowered hysteresis. A learning-based controller accommodates the inherent nonlinear robot actuation, which was validated with laser path-following tests. Submillimeter laser steering accuracy was demonstrated with a mean error < 0.20 mm. MRI compatibility testing demonstrated zero observable image artifacts during robot operation. Ex vivo tissue ablation and a cadaveric head-and-neck trial were carried out under MRI, where we employed MR thermometry to monitor the tissue ablation margin and thermal diffusion intraoperatively.