Modeling programmable drug delivery in bioelectronics with electrochemical actuation

Drug delivery systems featuring electrochemical actuation represent an emerging class of biomedical technology with programmable volume/flowrate capabilities for localized delivery. Recent work establishes applications in neuroscience experiments involving small animals in the context of pharmacological response. However, for programmable delivery, the available flowrate control and delivery time models fail to consider key variables of the drug delivery system––microfluidic resistance and membrane stiffness. Here we establish an analytical model that accounts for the missing variables and provides a scalable understanding of each variable influence in the physics of delivery process (i.e., maximum flowrate, delivery time). This analytical model accounts for the key parameters––initial environmental pressure, initial volume, microfluidic resistance, flexible membrane, current, and temperature––to control the delivery and bypasses numerical simulations allowing faster system optimization for different in vivo experiments. We show that the delivery process is controlled by three nondimensional parameters, and the volume/flowrate results from the proposed analytical model agree with the numerical results and experiments. These results have relevance to the many emerging applications of programmable delivery in clinical studies within the neuroscience and broader biomedical communities.

High-performing, linearly controllable electrochemical actuation of c-disordered δ-MnO2/Ni actuators

The pseudocapacitance-induced δ-MnO2/Ni electrochemical actuator combines outstanding actuation performance and good maneuverability at low driven voltages in a neutral electrolyte.

The Mechanical Effect of MnO2 Layers on Electrochemical Actuation Performance of Nanoporous Gold

This study investigated the electrochemical actuation behavior of nanoporous material during the capacitive process. The length change of nanoporous gold (npg) was in situ investigated in a liquid environment using the dilatometry technique. The mechanical effect of MnO2 layers was introduced in this work to improve the actuation characteristics of the npg samples. Our work found that the actuation behavior of npg sample could be significantly modulated with a covering of MnO2 layers. The electrochemical actuation amplitude was efficiently improved and strongly dependent on the thickness of MnO2 layers covered. Aside from the amplitude, the phase relation between the length change and the electrode potential was inverted when covering the MnO2 layer on the npg samples. This means the expansion of the npg samples and the contraction of samples covered with the MnO2 layer when electrochemical potential sweeps positively. A simple finite element model was built up to understand the effect of the MnO2 layer. The agreement between the simulation result and the experimental data indicates that the sign-inverted actuation-potential response of nanoporous gold contributes to the mechanical effect of MnO2. It is believed that our work could offer a deep understanding on the effect of the MnO2 layer on the electrochemical actuation and then provide a useful strategy to modulate the actuation performance of nanoporous metal materials.

Dual-Stimuli Responsive Carbon Nanotube Sponge-PDMS Amphibious Actuator

A dual-stimuli responsive soft actuator based on the three-dimensional (3D) porous carbon nanotube (CNT) sponge and its composite with polydimethylsiloxane (PDMS) was developed, which can realize both electrothermal and electrochemical actuation. The bimorph actuator exhibited a bending curvature of 0.32 cm−1·W−1 under electrothermal stimulation on land. The displacement of the electrochemical actuator could reach 4 mm under a 5 V applied voltage in liquid. The dual-responsive actuator has demonstrated the applications on multi-functional amphibious soft robots as a crawling robot like an inchworm, a gripper to grasp and transport the cargo and an underwater robot kicking a ball. Our study presents the versatility of the CNT sponge-based actuator, which can be used both on land and in water.

The promise of antireflective gold electrodes for optically monitoring the electro-deposition of single silver nanoparticles

Combined to electrochemical actuation, it allows the dynamic in situ visualization of the electrochemical growth and dissolution of individual Ag nanoparticles.