image: Design and application of living hydrogels as portable energy devices for neuron stimulation. a) 3D bioprinting of living hydrogels: schematic illustration depicting the 3D bioprinting process of living hydrogels. Within this construct, the bacterium S. oneidensis MR-1 is encapsulated within an alginate-based hydrogel matrix to maintain its metabolic activity and viability. b) Bio-energy devices for neuron stimulation: schematic representation of the bio-energy devices designed for the stimulation of neurons. The bio-battery is crucial for the charging of capacitors, which then deliver a precise and controlled electrical energy supply essential for effective nerve stimulation.
Credit: SIAT
Bio-battery, constructed by electroactive microorganisms, has unique advantages in physiological monitoring, tissue integration, and powering implantable devices due to its superior adaptability and biocompatibility. However, the development of miniaturized and portable bio-batteries that are plug-and-play and compatible with existing devices remains a challenge.
In a study published in Advanced Materials, a team led by ZHONG Chao, LIU Zhiyuan, and WANG Xinyu from the Shenzhen Institutes of Advanced Technology of the Chinese Academy of Sciences, collaborating with WANG Renheng from the Shenzhen University, developed a miniaturized, portable bio-battery, which enables the precise control over bioelectrical stimulation and physiological blood pressure signals.
The researchers encapsulated Shewanella oneidensis MR-1 biofilms within alginate hydrogels to develop living hydrogels, which can be 3-D printed into defined geometries for customized fabrication. Inspired by lithium-ion battery fabrication, they developed a miniaturized bio-battery (20 mm in diameter, 3.2 mm in height) using living hydrogel as the bio-anode ink, K3[Fe(CN)6]-containing alginate hydrogel as the cathode ink, and a Nafion membrane as the ion exchange membrane.
The bio-battery generated electricity from the metabolic activity of bacteria, enabling it with self-charging capabilities up to 10 cycles. It could also serve as the pseudo-battery for charge/discharge cycles with the coulombic efficiency of over 99.5% across 50 cycles, indicating lower energy losses. Impressively, the bacteria in the bio-battery maintained a high viability of over 70% across the entire process and 97.6% at the end of operation.
The bio-battery exhibited a specific capacity of 0.4 mAh g−1, a maximum power density of about 8.31 µW cm−2, and an energy density of 0.008 Wh/L. Although these values are lower than those of traditional lithium-ion batteries, the bio-battery provides a sustainable energy alternative by avoiding the use of critical raw materials such as cobalt and lithium, as well as environmentally hazardous components such as manganese and organic electrolytes.
Furthermore, the researchers explored the application potential of the bio-battery in nerve stimulation. By targeting the sciatic and vagus nerve, they demonstrated its precise control over bioelectrical stimulation and physiological blood pressure signals. This precise stimulation technique holds promise for developing novel physical therapy methods.
This study promotes the development of portable bio-devices while expanding the research frontiers in engineered living energy materials. It offers innovative solutions for the future development and application of sustainable energy.
Journal
Advanced Materials
Method of Research
Experimental study
Subject of Research
Not applicable
Article Title
3-D Printable Living Hydrogels as Portable Bio-energy Devices
Article Publication Date
5-Mar-2025