Achieving Flexibility and Output Force with ‘Liquid Crystal Polymer Actuators’

• Actuators
• Biomedical Applications
• Polymeric Materials
• Research Center for Macromolecules and Biomaterials

Actuators convert energy, such as electricity or hydraulics, into mechanical motion. With the growing demand for soft actuators, Masafumi Yoshio has been developing innovative materials that harness the unique properties of liquid crystals.

Dilemma Between Softness and High Output Force  

The sensation of touching objects far away as if they were right in front of you is made possible by ‘haptics,’ a tactile technology that conveys touch using force, vibration, or motion. Actuators, essential components of this technology, deliver these tactile experiences. Advanced tactile reproduction could revolutionize fields such as remote medical diagnostics and virtual reality, unlocking new possibilities for enhancing daily life.

As demand grows, actuators, traditionally made of metallic materials, are expected to bend flexibly and precisely control their force. One prominent example is the ‘polymer-based film actuator,’ which uses a polymer membrane containing ions sandwiched between flexible electrodes. When voltage is applied, the imbalance in ion distribution causes smaller negative ions to move toward the positively charged electrode, bending the membrane in that direction (Fig. 1). This mechanism underpins its functionality.

“Our current challenge is to achieve rapid and large deformations under low voltage. Polymer membranes, however, are composed of long entangled polymer chains, which create resistance as ions move through the material. To address this challenge and enable faster, larger deformations, one potential approach is to increase the ion content in the polymer membrane. Yet, this approach makes the membrane softer, reducing its ability to generate strong force,” Yoshio explains.