Advantages of iontronics
In the rapidly evolving world of big data and the Internet of Things (IoT), the imperative for efficient energy and information transmission is paramount. As we transition into the post-Moore era, conventional silicon-based semiconductor technology is approaching its physical limitations, rendering further performance enhancements increasingly arduous and costly. Within this context, the exigency for pioneering solutions such as iontronics has become more pronounced. Iontronics, which employs multivalent ions (e.g., Li⁺, Mg²⁺, Al³⁺) for charge transport, offers substantial advantages over traditional electronics dependent solely on electrons. This technology augments charge transmission and energy conversion efficiency, positing it as a promising alternative as conventional electronics near their threshold. A pivotal advantage of iontronics lies in its capability to execute intricate signal processing and data storage through the utilization of various ions, thereby amplifying system flexibility and functionality. Furthermore, iontronics can emulate biological neural signal transduction processes, employing ions that autonomously migrate along concentration gradients. This enables more efficient low-frequency signal transmission with reduced energy consumption. In conclusion, the post-Moore era mandates the advancement of efficient iontronics to satisfy the burgeoning demand for high-performance energy and information processing technologies.
The core of iontronics: The electrical double layer
In iontronics, the electrical double layer (EDL) governs electronic properties through ion transport and rearrangement, offering a novel paradigm for achieving efficient energy and information flow necessary for the post-Moore era. Comprehending the EDL formed at solid-liquid or liquid-liquid interfaces is pivotal in domains such as energy harvesting, storage, catalysis, and colloid formation. Consequently, the structure and composition of the EDL have been subjects of continuous investigation over the past two centuries. Recently, a two-step model of the EDL was introduced. This model posits that electron transfer and ionization reactions occur almost concurrently, leading to the simultaneous transfer of electrons and adsorption of ions on the dielectric surface to form the inner Helmholtz plane. Subsequently, under electrostatic forces, ions of opposite polarity adsorb onto the charged surface, forming the outer Helmholtz plane. According to this two-step model, the EDL exemplifies an exceptional ionic-electronic coupling interface, wherein the dynamics of ions and electrons can be regulated.
Constructing efficient triboiontronics by dynamic regulation of the EDL
In our study, controllable ion migration behavior was achieved by dynamically manipulating asymmetric EDL formation between dielectric substrates and liquids, thus creating efficient triboiontronics. By regulating the coverage of the charge-collecting layer on the dielectric substrate, we not only facilitated charge collection but also adjusted the contact electrification (CE) properties between the substrate and the liquid to form distinct EDLs. Dynamic regulation of CE between liquids and dielectric substrates with identical charge-collecting layers enabled asymmetric EDL formation, generating an ion concentration gradient and producing efficient ionic current in the physically adsorptive direct-current triboiontronic nanogenerator (PDC-TING). This configuration resulted in a peak power density of 8.45 W/m² and a transferred charge density of 412.54 mC/m². Introducing redox reactions by modifying metal charge collectors further enhanced performance, yielding a more efficient synergistic DC-TING (SDC-TING) with a peak power density of 38.64 W/m² and a transferred charge density of 540.70 mC/m². Both PDC-TING and SDC-TING exhibited several orders of magnitude increases in transferred charge density compared to hydrovoltaic technology and conventional TENGs by manipulating the EDL boundary. The synergistic regulation of EDLs balanced the charge density near the dielectric substrate, creating a tunable ionic-electronic coupling interface, thereby advancing the study of iontronics.
Applications and prospects of triboiontronics
The SDC-TING, as an integrated device for energy harvesting and storage, unveiled profound application prospects in the realms of energy and information flow. Specifically, in the field of energy, the SDC-TING could operate in two interrelated stages: the integrated energy harvesting and storage stage, followed by the separate energy storage stage. During the integrated stage, the SDC-TING synergistically generated more power, delivering an accelerated energy supply to electrical apparatuses such as capacitors. The subsequent separate energy storage stage substantially enhanced the stability of the SDC-TING. It could serve as an integrated power management system without complex conversion circuits to connect primary energy storage, energy harvester, and additional intermediate energy storage units, potentially opening new avenues for research in the efficient harvesting and storage of energy. In the field of information flow, the SDC-TING demonstrated the capability to regulate various ion fluxes, such as Na+ and Ca2+, by establishing a mechano-driven ion concentration gradient, thereby generating information flow. Ions carry essential information and perform specific functions in biological systems. For instance, Ca2+ signals activate neurotransmitter release, modulate neuronal function, and facilitate cardiac muscle relaxation efficiently. Na+ ions regulate blood pressure, volume, osmotic equilibrium, and enable excitation propagation by controlling action potential rate and duration. The property of SDC-TING allows it to mimic human tactile neural circuits, facilitating the development of bionic neurologic circuits. These circuits can perform threshold-sensing control functions, paving the way for future human-computer interaction and neuromorphic computing. This highlights the significant potential of SDC-TING in energy and information flow. In summary, the synergistic regulation of EDLs could balance the charge density in the vicinity of the dielectric substrate and create a tunable ionic-electronic coupling interface, facilitating in-depth studies of iontronics. Such triboiontronics could not only integrate energy harvesting and storage into one device but also offer a versatile platform for probing the ion dynamics and interface properties for neuroscience and futuristic brain-machine interface.
Remark
For more detailed information, please refer to the article “Triboiontronics with temporal control of electrical double layer formation”, https://doi.org/10.1038/s41467-024-50518-3. More in-depth communication can be carried out through the research group website “http://iontronics.group/en/”.
Efficient iontronics is needed in the post-Moore era
