Piezoionics Reading List - Preceding Works
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The development of piezoionic materials and devices has been propelled by foundational breakthroughs in flexible materials and bio-integrated electronics. Seminal work on soft/organic materials and organic electronic devices such as transistors established the critical importance of solution-processable materials and engineered interfaces as building blocks. Concurrently, the exploration of hydrogel ionotronics introduced the paradigm of using soft, ionic conductors to seamlessly bridge electronic circuits with biological systems. These parallel advances—mastering charge transport in organic solids and harnessing ionic transport in aqueous networks—provided the essential conceptual and material toolkit, creating the necessary preconditions for the subsequent emergence of the field of piezoionics.
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1. Organic electrochemical transistors
J. Rivnay, S. Inal, A. Salleo, R. M. Owens, M. Berggren, G. G. Malliaras
Nature Reviews Materials, 2018, 3, 17086. (DOI)
This work formalizes the device physics and realization of organic electrochemical transistors (OECTs), distinguishing this class of devices by their volumetric ionic-electronic coupling, where ions penetrate the entire organic semiconductor channel to modulate conductivity, enabling high transconductance. This mechanism is akin to the foundational principle for piezoionics, which transduces mechanical strain into ionic flux. This review surveys conjugated polymers like PEDOT:PSS for their mixed conduction and establishes design rules. Its significance lies in providing the core framework for bioelectronic sensors, circuits, and neuromorphic devices that interface with ionic environments.
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2. Multi-scale multi-mechanism design of tough hydrogels: building dissipation into stretchy networks
Xuanhe Zhao
Soft Matter, 2014, 10, 672-687. (DOI)
This review establishes a general design principle for tough hydrogels: to integrate mechanisms for dissipating mechanical energy while maintaining high elasticity, synthesizing decades of research into a unified framework. This framework is crucial for piezoionics, as robust, stretchable hydrogel matrices are a key class of ionic conductors, enabling durable devices that can withstand large, cyclic deformations. The work systematically catalogues material strategies—like double networks, hybrid crosslinkers, and fiber composites—that achieve this synergy. The proposed multi-scale, multi-mechanism integration guides the creation of next-generation materials. Its broad impact is foundational for developing durable soft materials for biomedical devices, soft robotics, and, critically, for enabling robust, high-performance piezoionic sensors and energy harvesters.
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3. Why are double network hydrogels so tough?
Jian Ping Gong
Soft Matter, 2010, 6, 2583–2590. (DOI)
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This paper elucidates the novel "sacrificial bond" toughening mechanism in double-network (DN) hydrogels, where a rigid, brittle first network fractures into clusters to dissipate massive energy, while a soft, ductile second network sustains large deformation. This principle provides a crucial material design blueprint for piezoionics, enabling the creation of hydrogels that are both ionically conductive and extremely tough to withstand mechanical cycles. It proposes an optimized asymmetric structure of a densely crosslinked polyelectrolyte (e.g., PAMPS) interpenetrated by a loosely crosslinked neutral polymer (e.g., PAAm). The resulting architecture forms a large damage zone at a crack tip, dramatically increasing fracture energy. Its significance is foundational, demonstrating that water-rich (~90%) materials can achieve rubber-like toughness, directly enabling the development of durable, load-bearing soft materials for biomedical implants and robust ionic conductors for sensors and soft robotics.
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4. Materials and mechanics for stretchable electronics
John A. Rogers, Takao Someya, Yonggang Huang
Science, 2010, 327, 1603–1607. (DOI)
This foundational review establishes the paradigm of using mechanics and novel material integration to create electronics that are soft, stretchable, and conformal, enabling intimate bio-integration. It connects to piezoionics by providing the critical device architecture—such as mesh designs on elastomers (e.g., PDMS)—that can host and protect functional materials (like ionic conductors) under large, cyclic deformation. The proposed methodologies include structuring brittle inorganic semiconductors into wavy or serpentine geometries and using elastic conductors (e.g., carbon nanotube gels). This design philosophy is significant for creating durable, high-performance interfaces between electronics and biological tissues, directly enabling the development of robust, skin-like sensors, health monitors, and bio-integrated devices that are essential for the practical application of piezoionic systems.
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5. Soft robotics: a perspective—current trends and prospects for the future
Carmel Majidi
Soft Robotics, 2014, 1, 5–11. (DOI)
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This perspective establishes soft robotics as an interdisciplinary field that requires materials with biological tissue-like compliance and multifunctionality, directly relevant to piezoionics by defining the need for soft, stretchable, and functional materials. It emphasizes the principle of compliance matching—where robots must match the mechanical properties of their environment (e.g., human tissue)—to ensure safe interaction and effective force distribution. This creates a critical application space for piezoionic materials, which can serve as soft, self-powered sensors or actuators within these compliant systems. The review highlights key enabling technologies like stretchable electronics (e.g., wavy circuits, liquid metal microfluidics) and artificial muscles (e.g., dielectric elastomers, IPMCs), outlining a roadmap for integrating functional materials into robots that are safe, versatile, and bio-integrated. Its impact is foundational for guiding the development of next-generation soft machines where piezoionic elements can provide sensing, energy harvesting, and actuation without compromising mechanical compatibility.
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6. Pursuing prosthetic electronic skin
Alex Chortos, Jia Liu, Zhenan Bao
Nature Materials, 2016, 15, 937–950. (DOI)
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This review establishes the comprehensive vision for creating fully functional, skin-like prosthetics that restore a natural sense of touch, directly relevant to piezoionics by defining the need for soft, multifunctional, and self-powered sensing systems. It systematically outlines the key requirements for electronic skin (e-skin): mechanical compliance (stretchable, durable, skin-like mechanics), multimodal sensing (pressure, strain, temperature, vibration), biomimetic signal encoding, and neural interfacing. The work highlights several transduction mechanisms critical for piezoionic development, particularly piezoelectric and triboelectric sensors for dynamic force sensing and self-powering, and capacitive/resistive sensors for static pressure. It also details strategies for achieving stretchability (buckling, rigid islands, intrinsically stretchable materials) and toughness, providing a material and device architecture roadmap. This review is foundational for piezoionics as it defines the performance benchmarks (sensitivity, response time, durability) and system integration challenges (sensor arrays, signal processing, neural interfaces) that piezoionic materials and devices must address to be viable in advanced biomedical applications like prosthetics and soft robotics.
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7. Gate dielectrics for organic field-effect transistors: new opportunities for organic electronics
Facchetti, A., Yoon, M.-H., & Marks, T. J.
Advanced Materials, 2005, 17(14), 1705–1725. (DOI)
This review's central contribution is identifying the gate dielectric—not just the semiconductor—as the critical interface for achieving high-performance, low-voltage organic transistors (OTFTs). It is foundational for organic electronics and connects directly to the field of iontronics, which has large intersection with piezoionics. The work proposes and analyzes three material classes—high-k inorganics, polymers, and self-assembled layers—as solutions for efficient, solution-processable dielectrics. This focus on the dielectric/semiconductor interface is significant for enabling low-power device architectures, which is essential for the broad, low-cost manufacturing of flexible and printed electronics.
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8. Hydrogel ionotronics
Yang, C., & Suo, Z.
Nature Reviews Materials, 2018, 3(6), 125–142. (DOI)
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This paper pioneers the concept of "hydrogel ionotronics," uniquely using soft, water-based ionic conductors to bridge living matter and electronics. It establishes the field by cataloguing first-generation devices like artificial muscles and skin, directly advancing the soft, bio-integrated concepts central to piezoionics. The core methodology employs stretchable, transparent hydrogels as the ionic material. The significance lies in its device architectures—such as laminated capacitors and ionic cables—enabling applications in wearable tech, soft robotics, and next-generation human-machine interfaces.
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