Yizhou Jiang

Ultrathin conductive hydrogels provide conformal and stable contact for flexible bioelectronics, which is critical for achieving the low impedance necessary for high-quality electrophysiological signal acquisition. However, their low modulus has made these hydrogel devices difficult to fabricate and handle. To overcome this, we present an on-demand formation strategy for creating ready-to-use, ultrathin (down to 1 micrometer) hydrogel-based bioelectronics that combine tissue-like softness with ready-to-use functionality. By using cross-linked electrospun polyvinyl alcohol (PVA) fiber mats, we produce liquid metal–patterned hydrogel tattoos (LMHTs). These devices transform from easy-to-handle dry films into adhesive, conformal hydrogel interfaces upon hydration. The resulting LMHTs are ultralight (0.9 milligrams per square centimeter), exhibit ultralow skin contact impedance (1.2 kilohms at 1 kilohertz), and show outstanding biocompatibility. We demonstrate their utility in diverse on-skin and implantable applications, including electrocardiogram recording, multichannel electromyogram mapping, neuromuscular electrical stimulation, and in vivo cardiac monitoring on a beating rat heart. This work offers a scalable and practical approach for generating high-performance, ultrathin hydrogel bioelectronics.

Plaque accumulation in coronary arteries causes stenoses, reducing blood flow and increasing the risk of cardiovascular disorders such as heart attacks. To assess the physiological impact of blood pressure across a stenosis, commercial pressure guidewires measure the fractional flow reserve using optical, piezoresistive or piezoelectric sensors, which suffer from brittleness, limited manoeuvrability and high costs. Here we report an iontronic tip-sensing guidewire (ITG) that integrates a thin iontronic tip sensor in a commercial workhorse guidewire via iontronic-based signal transmission, leveraging the ionic nature of human tissues. Intravascular pressure changes induce a capacitance difference at the interface of the metal and ionic gel of the ITG, allowing detection of subtle pressure changes in blood flow, substantially outperforming commercial guidewires. The ITG is free of embedded conductive leads needed in other pressure guidewires to ensure an ideal torque ratio for high manoeuvrability, and we validated its effectiveness and sensitivity in rabbit, goat and pig models in vivo. The compatibility of the ITG with commercial horsework guidewires will upgrade the design of interventional medical devices.

The advancement of electrophysiological mapping for cardiac arrhythmias relies critically on overcoming key interface challenges: long-term biocompatibility, spatial resolution limitations, and mechanical mismatch with dynamic cardiac tissue. To address these, we developed a rapid encapsulation method for liquid metal electrode arrays at the 10-μm scale, enabling the fabrication of ultrahigh-density and flexible sensor arrays (∼28570 sensors/cm²) within 30 min. It constructs a fully foldable, high-density heart-machine interface deployable via minimally invasive access (2 reentrant pattern in ventricular fibrillation) while maintaining long-term reliability (100% electrode functionality over 98 days). This technology holds promise for advancing diverse human-machine interfaces for other organs and tissues, enabling the integration of multiple organs and even the whole body for comprehensive health management.

C-peptide is a critical biomarker for evaluating pancreatic β cell function and managing diabetes. However, conventional methods such as enzyme-linked immunosorbent assay are limited by lengthy processing times and the necessity for invasive sample collection. This study introduces a regenerable, portable, and wearable device for minimally invasive, real-time monitoring of C-peptide in dermal interstitial fluid (ISF). The device uses a microneedle array and negative pressure extraction for ISF collection. A double-antibody sandwich approach was used to detect C-peptide, and an antibody regeneration strategy was applied to remove bound antigen-antibody complexes, thereby achieving repeatable detection, enabling at least 10 detection assays on the same chip with negligible signal attenuation. The compact design features a skin contact area of only 3 cm by 5.4 cm and excellent biocompatibility. Integrated with a mobile app, the device provides real-time concentration reading. Mouse and rabbit tests confirm effective ISF sampling and monitoring accuracy, demonstrating its potential for at-home diabetes management and broader wearable biosensing applications.

Gallium-based liquid metal (LM) exhibits exceptional properties such as high conductivity and biocompatibility, rendering it highly valuable for the development of conformal bioelectronics. When combined with polymers, liquid metal-polymer conductors (MPC) offer a versatile platform for fabricating conformal cyborg devices, enabling functions such as sensing, restoration, and augmentation within the human body. This review focuses on the synthesis, fabrication, and application of MPC-based cyborg devices. The synthesis of functional materials based on LM and the fabrication techniques for MPC-based devices are elucidated. The review provides a comprehensive overview of MPC-based cyborg devices, encompassing their applications in sensing diverse signals, therapeutic interventions, and augmentation. The objective of this review is to serve as a valuable resource that bridges the gap between the fabrication of MPC-based conformal devices and their potential biomedical applications.

By setting the reverse flow channel at the end of the abruptly broadened segment, the flow field can be fundamentally changed, and the separation performance can be improved comprehensively compared with the traditional iPFF device.