# CTF-based soft touch actuator for playing electronic piano

## TL;DR

A new soft robotic actuator using covalent triazine frameworks enables precise, low-voltage movements suitable for tasks like playing an electronic piano.

## Contribution

A novel electro-ionic soft actuator based on metal-free covalent triazine frameworks (CTFs) achieves high bending deformation under ultralow voltages.

## Key findings

- The actuator achieves a peak-to-peak displacement of 17.0 mm under ±0.5 V input voltage.
- The device demonstrates 4 times reduced phase delay compared to a pure PEDOT-PSS-based actuator.
- The actuator successfully performed precise tasks, such as playing an electronic piano, on fragile displays.

## Abstract

In the field of bioinspired soft robotics, to accomplish sophisticated tasks in human fingers, electroactive artificial muscles are under development. However, most existing actuators show a lack of high bending displacement and irregular response characteristics under low input voltages. Here, based on metal free covalent triazine frameworks (CTFs), we report an electro-ionic soft actuator that shows high bending deformation under ultralow input voltages that can be implemented as a soft robotic touch finger on fragile displays. The as-synthesized CTFs, derived from a polymer of intrinsic microporosity (PIM-1), were combined with poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) to make a flexible electrode for a high-performance electro-ionic soft actuator. The proposed soft touch finger showed high peak-to-peak displacement of 17.0 mm under ultralow square voltage of ±0.5 V, with 0.1 Hz frequency and 4 times reduced phase delay in harmonic response compared with that of a pure PEDOT-PSS-based actuator. The significant actuation performance is mainly due to the unique physical and chemical configurations of CTFs electrode with highly porous and electrically conjugated networks. On a fragile display, the developed soft robotic touch finger array was successfully used to perform soft touching, similar to that of a real human finger; device was used to accomplish a precise task, playing electronic piano.

Actuators often show a lack of high bending displacement with back relaxation and irregular response characteristics under low input voltages. Here, the authors demonstrate a covalent triazine framework-based electroionic soft actuator that shows controllable high bending deformation under low input voltages.