Related Experiment Video
Updated: Sep 30, 2025

Author Spotlight: Studying Bacterial Growth in 3D Hydrogel Matrices
Published on: January 19, 2024
High Energy and Power Density Peptidoglycan Muscles through Super-Viscous Nanoconfined Water
Haozhen Wang1,2, Zhi-Lun Liu1,3, Jianpei Lao1,3
1Advanced Science Research Center (ASRC), The City University of New York, 85 St. Nicholas Terrace, New York, NY, 10031, USA.
Abstract:
Water-responsive (WR) materials that reversibly deform in response to humidity changes show great potential for developing muscle-like actuators for miniature and biomimetic robotics. Here, it is presented that Bacillus (B.) subtilis' peptidoglycan (PG) exhibits WR actuation energy and power densities reaching 72.6 MJ m-3 and 9.1 MW m-3 , respectively, orders of magnitude higher than those of frequently used actuators, such as piezoelectric actuators and dielectric elastomers. PG can deform as much as 27.2% within 110 ms, and its actuation pressure reaches ≈354.6 MPa. Surprisingly, PG exhibits an energy conversion efficiency of ≈66.8%, which can be attributed to its super-viscous nanoconfined water that efficiently translates the movement of water molecules to PG's mechanical deformation. Using PG, WR composites that can be integrated into a range of engineering structures are developed, including a robotic gripper and linear actuators, which illustrate the possibilities of using PG as building blocks for high-efficiency WR actuators.
Related Concept Videos
ATP Driven Pumps I: An Overview
There are four main types of ATP-driven pumps - P-type, V-type, F-type, and ABC transporter. All these pumps are of varying complexities and...
Mechanical Protein Functions
Strain-Energy Density
In the elastic region of a material, the relationship between the stress and the strain is linear and follows Hooke's Law. The strain energy density in this...
ATP Driven Pumps III: V-type Pumps
The peripheral or cytosolic V1 domain with eight subunits is involved in ATP hydrolysis. The integral or transmembrane V0 domain containing at least five subunits...
ATP Driven Pumps II: P-type Pumps
A typical P-type pump has three cytosolic domains: nucleotide-binding (N), phosphorylation (P), and activator (A) domains. These domains are connected to the membrane-spanning helices by short amino acid segments. ATP hydrolysis and covalent phosphoenzyme intermediate formation are crucial parts of the catalytic cycle. At the highly...
Flagella and Motility in Bacteria

