Ionic Actuators as Manipulators for Microscopy

Abstract

Non-destructive handling of soft biological samples at the cellular level is becoming increasingly relevant in life sciences. In particular, spatially dense arrangements of soft manipulators with the capability of in situ monitoring via optical and electron microscopes promises new and exciting experimental techniques. The currently available manipulation technologies offer high positioning accuracy, yet these devices significantly grow in complexity in achieving compliance. We explore soft and compliant actuator material with a mechanical response similar to gel-like samples for perspective miniaturized manipulators. First, we demonstrate three techniques for rendering the bulk sheet-like electroactive material, the ionic and capacitive laminate (ICL), into a practical manipulator. We then show that these manipulators are also highly compatible with electron optics. Finally, we explore the performance of an ICL manipulator in handling a single large cell. Intrinsic compliance, miniature size, simple current-driven actuation, and negligible interference with the imaging technologies suggest a considerable perspective for the ICL in spatially dense arrays of compliant manipulators for microscopy.

Fabrication of Carbon-Based Ionic Electromechanically Active Soft Actuators

“…It has two tasks: prevent electron conductivity (short circuits) between the electrodes while enabling high ionic conductivity. Modifications to the membrane could serve several purposes, for example tool integration as introduced by Must et al 24 or the addition of new properties (e.g., biocompatibility, biodegradability or different mechanical properties). The current fabrication method could be modified to use other polymers and electrolytes in the membrane to introduce new properties to the active laminate.…”

“…Making an ion-conductive textile-reinforced membrane that might be useful when planning to use custom polymers (i.e., polymers not available as commercial (filtration) membranes), custom membrane thicknesses, ionic liquids with higher viscosity or when integrating tools into the actuator. Here we show the basic procedure for textile-reinforced membrane fabrication that can, for example, be modified to include tools or tubing (see Ref 24 for more information). NOTE: Use a stretch film that can withstand stirring at 70 °C (e.g., the melting point of Parafilm is just 60 °C, and therefore Parafilm would not be suitable for this application).…”

“…Typically, step voltages of ±2 V or less have been used to drive this type of actuators. See Ref 24 for more information on actuator control considerations.…”

“…The inclusion of a passive reinforcement in the membrane was first introduced by Kaasik et al 18 to tackle the above-mentioned problems in the actuator manufacturing process. The inclusion of a woven textile reinforcement (see also Figure 3B and 3D) further introduces the ability to integrate tools into the active composite 24 or to develop smart textiles…”

Modeling and Experimental Analysis of the Mass Loading Effect on Micro-Ionic Polymer Actuators Using Step Response Identification

“…In recent years, ionic electroactive polymer-based actuators (IEAPs) have attracted global interest among scientists. IEAPs are believed to have potential utility in biomedical applications [7], [8], such as steerable microcatheters [9], [10], microscopy [11], drug delivery [12]- [16], position-controlled microinjection [17], imaging [18], and microsurgical tools [19].…”