In biological systems, complex neural networks with highly polarized synaptic interfaces are responsible for the processing and transmission of complex biosignals. Inspired by neural interphase biosignal gate architectures, researchers led by Professor Wen Liping from the Technical Institute of Physics and Chemistry of the Chinese Academy of Sciences and Professor Zhao Jiguang from the University of Chinese Academy of Sciences developed the two-phase biosignal gate with their collaborators. gel iontronics with cascade heterointerface properties to achieve universal electron-ion transfer signal

Electronic and ionic devices have attracted great attention as they bridge the communication gap between abiotic and biotic interfaces, finding important applications in neural electrodes, neuroprostheses, and implantable smart devices. However, state-of-the-art electronics and iononics have been limited due to the inability of monotonic and single electron/ion signals to correspond to more biocompatible information.

Therefore, complex recognition and precise control of various bioionic signals in artificial devices for complex biological environments remains a major challenge. In this study, by mimicking the hierarchical interphase transition mechanisms of neural networks, researchers developed cascading heterogeneous biphasic gel (HBG) iontronics, which facilitates a variety of ion transfer between environments.

According to the researchers, HBG materials were synthesized using a controlled phase separation liquid-liquid polymerization strategy that combines ion-rich internal phases into a continuous, low-conductivity phase. In the ion transfer process, numerous hetero interfaces in HBG materials have played a crucial role in determining the free energy transfer barriers encountered by ions and their hydration–dehydration states. This significantly increased the variation in conduction between different ions by several orders of magnitude.

In this way, multi-ion hierarchical signal transduction can be realized, which is strongly associated with the hierarchical mismatch of energy barriers of ion transfer. In addition, a chemically enhanced HBG system derived from a synergistic combination of specific ligand groups was successfully designed for selective ionic interphase signal transduction.

Using this system, the researchers achieved successful regulation of cardiac electrical activity of frog hearts by various biofunctional neuro-humoral ion signals derived from the HBG-based ion synapse.

Leveraging this novel ion gating mechanism and programmable ion conduction properties, HBG iontronics can enable the conversion of electronic input signals into programmable bioion signals to serve a variety of biocommunication environments. Therefore, HBG iontronics are expected to accelerate progress in various biotechnological applications.