Elastomeric Transistor with Softness and Robustness Comparable to Cloth

Estimated reading time: 4 minutes

The Young’s modulus and the elastic limit of the consitutent materials of the transistor, as well as variety of metals, plastics, and fabrics are summarized in the Fig.2, as indices of flexibility and toughness. Young’s modulus is the ratio of the stress to the strain and indicates how soft the material is. The elastic limit is the maximum strain under which the material can keep reversible stretchability and flexibility and indicates how stretchable it is. Figure 2 indicates all the constituent materials of the transistor (the conductive SWCNT rubber composite, the ion gel, and the silicone rubber) possess softness and robustness similar to those of fabrics.

Figure 2: The Young’s modulus and the elastic limit for each of the constituent materials of the transistor and various other materials

Figure 3 shows the characteristics of the transistor before and after being stepped on by a high-heeled shoe (pressure: about 2.5 MPa). Because all of the materials deformed integrally, the concentration of stress, strain, etc. at the interface was reduced and almost no change was observed in the characteristics of the transistor (e.g. in the on-current and the on/off ratio) after being stepped. The transistor did not break and continued to maintain its characteristics, despite being subjected to this large amount of pressure—possibly one of the most severe loads it may be exposed to in everyday life.

Figure 3: The transistor being “stepped on” by the heel of a high-heeled shoe (main photo), and its performance before and after the event (inset)

Future Plans

The researchers plan to combine the transistor with flexible sensors and flexible energy devices to develop a human-monitoring system such as a human body-pressure distribution-sensing system for medical use. Their goal is to develop human-friendly electronic devices that can be worn just like clothes and place no burden on the human body.

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