Hu Li

Self‐Powered Pulse Sensor for Antidiastole of Cardiovascular Disease

Cardiovascular diseases are the leading cause of death globally; fortunately, 90% of cardiovascular diseases are preventable by long-term monitoring of physiological signals. Stable, ultralow power consumption, and high-sensitivity sensors are significant for miniaturized wearable physiological signal monitoring systems. Here, this study proposes a flexible self-powered ultrasensitive pulse sensor (SUPS) based on triboelectric active sensor with excellent output performance (1.52 V), high peak signal-noise ratio (45 dB), long-term performance (107 cycles), and low cost price. Attributed to the crucial features of acquiring easy-processed pulse waveform, which is consistent with second derivative of signal from conventional pulse sensor, SUPS can be integrated with a bluetooth chip to provide accurate, wireless, and real-time monitoring of pulse signals of cardiovascular system on a smart phone/PC. Antidiastole of coronary heart disease, atrial septal defect, and atrial fibrillation are made, and the arrhythmia (atrial fibrillation) is indicative diagnosed from health, by characteristic exponent analysis of pulse signals accessed from volunteer patients. This SUPS is expected to be applied in self-powered, wearable intelligent mobile diagnosis of cardiovascular disease in the future.

Robust Multilayered Encapsulation for High-Performance Triboelectric Nanogenerator in Harsh Environment

Harvesting biomechanical energy especially in vivo is of special significance for sustainable powering of wearable/implantable electronics. The triboelectric nanogenerator (TENG) is one of the most promising solutions considering its high efficiency, low cost, light weight, and easy fabrication, but its performance will be greatly affected if there is moisture or liquid leaked into the device when applied in vivo. Here, we demonstrate a multiple encapsulation process of the TENG to maintain its output performance in various harsh environments. Through systematic studies, the encapsulated TENG showed great reliability in humid or even harsh environment over 30 days with a stability index of more than 95%. Given its outstanding reliability, the TENG has the potential to be applied in variety of circumstances to function as a sustainable power source for self-powered biomedical electronics and environmental sensing systems.

Fully Bioabsorbable Natural‐Materials‐Based Triboelectric Nanogenerators

Implantable medical devices provide an effective therapeutic approach for neurological and cardiovascular diseases. With the development of transient electronics, a new power source with biocompatibility, controllability, and bioabsorbability becomes an urgent demand for medical sciences. Here, various fully bioabsorbable natural-materials-based triboelectric nanogenerators (BN-TENGs), in vivo, are developed. The triboelectric series of five natural materials is first ranked, it provides a basic knowledge for materials selection and device design of the TENGs and other energy harvesters. Various triboelectric outputs of these natural materials are achieved by a single material and their pairwise combinations. The maximum voltage, current, and power density reach up to 55 V, 0.6 µA, and 21.6 mW m-2 , respectively. The modification of silk fibroin encapsulation film makes the operation time of the BN-TENG tunable from days to weeks. After completing its function, the BN-TENG can be fully degraded and resorbed in Sprague-Dawley rats, which avoids a second operation and other side effects. Using the proposed BN-TENG as a voltage source, the beating rates of dysfunctional cardiomyocyte clusters are accelerated and the consistency of cell contraction is improved. This provides a new and valid solution to treat some heart diseases such as bradycardia and arrhythmia.

Thermo-Driven Evaporation Self-Assembly and Dynamic Analysis of Homocentric Carbon Nanotube Rings

MWCNTs self-assemble into various homocentric rings in a thermo-driven self-assembly system. Closely packed and scatteredly packed MWCNT rings self-assemble on a Si-SiO2 substrate, whereas on a Au substrate smoothly packed MWCNT rings, rings with waviness, and rings with shuttle-like holes are seen to self-assemble. The dynamic self-assembly process includes convection flow and swirling flow.

Tuning peptide self-assembly by an in-tether chiral center

Peptide nanomaterials were assembled by using helical peptides and served as active materials in supercapacitors. The self-assembly of peptides into ordered nanostructures is important for understanding both peptide molecular interactions and nanotechnological applications. However, because of the complexity and various self-assembling pathways of peptide molecules, design of self-assembling helical peptides with high controllability and tunability is challenging. We report a new self-assembling mode that uses in-tether chiral center-induced helical peptides as a platform for tunable peptide self-assembly with good controllability. It was found that self-assembling behavior was governed by in-tether substitutional groups, where chirality determined the formation of helical structures and aromaticity provided the driving force for self-assembly. Both factors were essential for peptide self-assembly to occur. Experiments and theoretical calculations indicate long-range crystal-like packing in the self-assembly, which was stabilized by a synergy of interpeptide π-π and π-sulfur interactions and hydrogen bond networks. In addition, the self-assembled peptide nanomaterials were demonstrated to be promising candidate materials for applications in biocompatible electrochemical supercapacitors.

Wearable Wire-Shaped Symmetric Supercapacitors Based on Activated Carbon-Coated Graphite Fibers

With the advantages of being lightweight, flexible, and wearable, wire-shaped supercapacitors have received tremendous attention in wearable and portable power sources in recent years. Considering the demands for large-scale applications, it is necessary to explore a facile and convenient preparation approach for wire-shaped supercapacitors. Herein, we reported a simple approach to fabricate wire-shaped electrodes by a dipping method, which possessed a nitric acid-activated graphite fiber core and an activated carbon-coating layer structure. Parallel and symmetric all-solid-state wire-shaped supercapacitors (PWSCs) based on the electrodes were fabricated. The as-fabricated PWSC showed high energy density (6.60 W h/kg, 8.08 mW h/cm, and 1 mV/s) and power density (253 mW/kg, 0.31 mW/cm, and 100 mV/s) and excellent flexibility. Furthermore, this wire-shaped supercapacitor may bring broader application prospects for energy storage devices in future wearable electronic areas.