Conductive and Stretchable Elastomers With Tissue-Matched Softness for Ultrasoft Electronics
Abstract (summary)
Understanding biological systems and mimicking their functions require electronic tools that can seamlessly interact with biological systems and possess similar mechanical characteristics. These tools play a crucial role in advancing capabilities related to mimicking sensing behaviours of biological systems and measuring vital signs reflecting general physiological states, enabling biomimetic designs to enhance interactions with humans. In particular, there is a growing demand for ultrasoft electronics (e.g., with a Young’s modulus E <30 kPa and stretchability >100%). Their applications range from wearable electronics used on skins to implantable electronics for brains and neurons. Designing such tools requires materials that not only match the softness and stretchability of biological tissues but also exhibit suitable conductivities for recording and transmitting bioelectronic signals. However, there is an inherent mechanical mismatch between biological tissues and conductive materials used in conventional electronics, which can lead to decay in electrical performance of devices and potential damage to tissues. Therefore, a key material challenge for these applications lies in replicating the dynamic mechanical characteristics-such as softness and stretchability-found in biological systems, while maintaining high electrical performance, such as electronic conductivity and/or ionic conductivity, for long-term use.
To address these challenges, this thesis focused on the development of conductive and stretchable elastomers with tissue-matched softness for ultrasoft electronics. Hydrogels and bottlebrush elastomers (BBEs) were employed as the ultrasoft and stretchable material matrix, with tunable conductivity (electronic conductivity and/or ionic conductivity) enabled by incorporating conductive components (e.g., polyelectrolytes, carbon nanotubes, ionic liquids, and conducting polymers, respectively). Specifically, the thesis presents the development of ionically conductive hydrogels (doped with oppositely-charged polyelectrolytes), electronically conductive BBEs [polydimethylsiloxane (PDMS) BBEs mixed with single-wall carbon nanotubes], ionically conductive BBEs [poly(ethylene glycol) (PEG) BBEs blended with ionic liquids], and mixed ionically-electronically conductive BBEs (PEG BBEs incorporated with conducting polymers [poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS)]. Furthermore, these materials were fabricated into ultrasoft electronics, and applied in iontronics, human-machine interactions, wearable electronics, soft robotics, electrophysiological recordings, and implantable bioelectronic neural interfaces.
Indexing (details)
Engineering;
Materials science;
Industrial engineering
0794: Materials science
0537: Engineering
0546: Industrial engineering
