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Zhong Y, Lopez-Larrea N, Alvarez-Tirado M, Casado N, Koklu A, Marks A, Moser M, McCulloch I, Mecerreyes D, Inal S. Eutectogels as a Semisolid Electrolyte for Organic Electrochemical Transistors. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2024; 36:1841-1854. [PMID: 38435047 PMCID: PMC10902863 DOI: 10.1021/acs.chemmater.3c02385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 01/09/2024] [Accepted: 01/10/2024] [Indexed: 03/05/2024]
Abstract
Organic electrochemical transistors (OECTs) are signal transducers offering high amplification, which makes them particularly advantageous for detecting weak biological signals. While OECTs typically operate with aqueous electrolytes, those employing solid-like gels as the dielectric layer can be excellent candidates for constructing wearable electrophysiology probes. Despite their potential, the impact of the gel electrolyte type and composition on the operation of the OECT and the associated device design considerations for optimal performance with a chosen electrolyte have remained ambiguous. In this work, we investigate the influence of three types of gel electrolytes-hydrogels, eutectogels, and iongels, each with varying compositions on the performance of OECTs. Our findings highlight the superiority of the eutectogel electrolyte, which comprises poly(glycerol 1,3-diglycerolate diacrylate) as the polymer matrix and choline chloride in combination with 1,3-propanediol deep eutectic solvent as the ionic component. This eutectogel electrolyte outperforms hydrogel and iongel counterparts of equivalent dimensions, yielding the most favorable transient and steady-state performance for both p-type depletion and p-type/n-type enhancement mode transistors gated with silver/silver chloride (Ag/AgCl). Furthermore, the eutectogel-integrated enhancement mode OECTs exhibit exceptional operational stability, reflected in the absence of signal-to-noise ratio (SNR) variation in the simulated electrocardiogram (ECG) recordings conducted continuously over a period of 5 h, as well as daily measurements spanning 30 days. Eutectogel-based OECTs also exhibit higher ECG signal amplitudes and SNR than their counterparts, utilizing the commercially available hydrogel, which is the most common electrolyte for cutaneous electrodes. These findings underscore the potential of eutectogels as a semisolid electrolyte for OECTs, particularly in applications demanding robust and prolonged physiological signal monitoring.
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Affiliation(s)
- Yizhou Zhong
- Organic
Bioelectronics Laboratory, Biological and Environmental Science and
Engineering Division, King Abdullah University
of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Naroa Lopez-Larrea
- POLYMAT,
University of the Basque Country UPV/EHU, Avenida Tolosa 72, Donostia-San
Sebastian, Guipuzcoa 20018, Spain
| | - Marta Alvarez-Tirado
- POLYMAT,
University of the Basque Country UPV/EHU, Avenida Tolosa 72, Donostia-San
Sebastian, Guipuzcoa 20018, Spain
| | - Nerea Casado
- POLYMAT,
University of the Basque Country UPV/EHU, Avenida Tolosa 72, Donostia-San
Sebastian, Guipuzcoa 20018, Spain
- IKERBASQUE,
Basque Foundation for Science, Plaza Euskadi 5, Bilbao 48009, Spain
| | - Anil Koklu
- Organic
Bioelectronics Laboratory, Biological and Environmental Science and
Engineering Division, King Abdullah University
of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Adam Marks
- Department
of Chemistry, University of Oxford, Oxford OX1 3TF, U.K.
| | - Maximilian Moser
- Department
of Chemistry, University of Oxford, Oxford OX1 3TF, U.K.
| | - Iain McCulloch
- Department
of Chemistry, University of Oxford, Oxford OX1 3TF, U.K.
| | - David Mecerreyes
- POLYMAT,
University of the Basque Country UPV/EHU, Avenida Tolosa 72, Donostia-San
Sebastian, Guipuzcoa 20018, Spain
- IKERBASQUE,
Basque Foundation for Science, Plaza Euskadi 5, Bilbao 48009, Spain
| | - Sahika Inal
- Organic
Bioelectronics Laboratory, Biological and Environmental Science and
Engineering Division, King Abdullah University
of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
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2
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Zhong Y, Nayak PD, Wustoni S, Surgailis J, Parrado Agudelo JZ, Marks A, McCulloch I, Inal S. Ionic Liquid Gated Organic Electrochemical Transistors with Broadened Bandwidth. ACS APPLIED MATERIALS & INTERFACES 2023. [PMID: 37997899 DOI: 10.1021/acsami.3c11214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2023]
Abstract
The organic electrochemical transistor (OECT) is a biosignal transducer known for its high amplification but relatively slow operation. Here, we demonstrate that the use of an ionic liquid as the dielectric medium significantly improves the switching speed of a p-type enhancement-mode OECT, regardless of the gate electrode used. The OECT response time with the ionic liquid improves up to ca. 41-fold and 46-fold for the silver/silver chloride (Ag/AgCl) and gold (Au) gates, respectively, compared with devices gated with the phosphate buffered saline (PBS) solution. Notably, the transistor gain remains uncompromised, and its maximum is reached at lower voltages compared to those of PBS-gated devices with Ag/AgCl as the gate electrode. Through ultraviolet-visible spectroscopy and etching X-ray photoelectron spectroscopy characterizations, we reveal that the enhanced bandwidth is associated with the prediffused ionic liquid inside the polymer, leading to a higher doping level compared to PBS. Using the ionic liquid-gated OECTs, we successfully detect electrocardiography (ECG) signals, which exhibit a complete waveform with well-distinguished features and a stable signal baseline. By integrating nonaqueous electrolytes that enhance the device bandwidth, we unlock the potential of enhancement-mode OECTs for physiological signal acquisition and other real-time biosignal monitoring applications.
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Affiliation(s)
- Yizhou Zhong
- Organic Bioelectronics Laboratory, Biological and Environmental Science and Engineering Division (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
- Computational Bioscience Research Center, BESE, KAUST, Thuwal 23955, Saudi Arabia
| | - Prem D Nayak
- Organic Bioelectronics Laboratory, Biological and Environmental Science and Engineering Division (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
- Computational Bioscience Research Center, BESE, KAUST, Thuwal 23955, Saudi Arabia
| | - Shofarul Wustoni
- Organic Bioelectronics Laboratory, Biological and Environmental Science and Engineering Division (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
- Computational Bioscience Research Center, BESE, KAUST, Thuwal 23955, Saudi Arabia
| | - Jokubas Surgailis
- Organic Bioelectronics Laboratory, Biological and Environmental Science and Engineering Division (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
- Computational Bioscience Research Center, BESE, KAUST, Thuwal 23955, Saudi Arabia
| | - Jessica Z Parrado Agudelo
- Organic Bioelectronics Laboratory, Biological and Environmental Science and Engineering Division (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
- Computational Bioscience Research Center, BESE, KAUST, Thuwal 23955, Saudi Arabia
| | - Adam Marks
- Department of Chemistry, University of Oxford, Oxford OX1 3TF, United Kingdom
| | - Iain McCulloch
- Department of Chemistry, University of Oxford, Oxford OX1 3TF, United Kingdom
| | - Sahika Inal
- Organic Bioelectronics Laboratory, Biological and Environmental Science and Engineering Division (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
- Computational Bioscience Research Center, BESE, KAUST, Thuwal 23955, Saudi Arabia
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3
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Sun Z, Khau B, Dong H, Takacs CJ, Yuan S, Sun M, Mosevitzky Lis B, Nguyen D, Reichmanis E. Carboxyl-Alkyl Functionalized Conjugated Polyelectrolytes for High Performance Organic Electrochemical Transistors. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2023; 35:9299-9312. [PMID: 38027548 PMCID: PMC10653087 DOI: 10.1021/acs.chemmater.3c02103] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 10/10/2023] [Accepted: 10/18/2023] [Indexed: 12/01/2023]
Abstract
Contemporary design principles for organic mixed ionic electronic conductors (OMIECs) are mostly based on the ethylene glycol moiety, which may not be representative of the OMIEC class as a whole. Furthermore, glycolated polymers can be difficult to synthesize and process effectively. As an emerging alternative, we present a series of polythiophenes functionalized with a hybrid carboxyl-alkyl side chain. By variation of the alkyl spacer length, a comprehensive evaluation of both the impact of carboxylic acid functionalization and alkyl spacer length was conducted. COOH-functionalization endows the polymer with preferential intrinsic low-swelling behavior and water processability to yield solvent-resistant conjugated polyelectrolytes while retaining substantial electroactivity in aqueous environments. Advanced in situ techniques, including time-resolved spectroelectrochemistry and Raman spectroscopy, are used to interrogate the materials' microstructure, ionic-electronic coupling, and operational stability in devices. To compare these materials' performance to state-of-the-art technology for the design of OMIECs, we benchmarked the materials and demonstrated significant application potential in both planar and interdigitated organic electrochemical transistors (OECTs). The polythiophene bearing carboxyl-butyl side chains exhibits greater electrochemical performance and faster doping kinetics within the polymer series, with a record-high OECT performance among conjugated polyelectrolytes ([μC*]pOECT = 107 ± 4 F cm-1 V-1 s-1). The results provide an enhanced understanding of structure-property relationships for conjugated polyelectrolytes operating in aqueous media and expand the materials options for future OMIEC development. Further, this work demonstrates the potential for conjugated polymers bearing alkyl-COOH side chains as a path toward robust OMIEC designs that may facilitate further facile (bio)chemical functionalization for a range of (bio)sensing applications.
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Affiliation(s)
- Zeyuan Sun
- Department
of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Brian Khau
- School
of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Hao Dong
- Department
of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Christopher J. Takacs
- Stanford
Synchrotron Radiation Lightsource SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Shuhan Yuan
- Department
of Applied Health Science, School of Public Health, Indiana University, Bloomington, Indiana 47405, United States
| | - Mengting Sun
- Department
of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Bar Mosevitzky Lis
- Department
of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Dang Nguyen
- Department
of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Elsa Reichmanis
- Department
of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, United States
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Ohayon D, Druet V, Inal S. A guide for the characterization of organic electrochemical transistors and channel materials. Chem Soc Rev 2023; 52:1001-1023. [PMID: 36637165 DOI: 10.1039/d2cs00920j] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The organic electrochemical transistor (OECT) is one of the most versatile devices within the bioelectronics toolbox, with its compatibility with aqueous media and the ability to transduce and amplify ionic and biological signals into an electronic output. The OECT operation relies on the mixed (ionic and electronic charge) conduction properties of the material in its channel. With the increased popularity of OECTs in bioelectronics applications and to benchmark mixed conduction properties of channel materials, the characterization methods have broadened somewhat heterogeneously. We intend this review to be a guide for the characterization methods of the OECT and the channel materials used. Our review is composed of two main sections. First, we review techniques to fabricate the OECT, introduce different form factors and configurations, and describe the device operation principle. We then discuss the OECT performance figures of merit and detail the experimental procedures to obtain these characteristics. In the second section, we shed light on the characterization of mixed transport properties of channel materials and describe how to assess films' interactions with aqueous electrolytes. In particular, we introduce experimental methods to monitor ion motion and diffusion, charge carrier mobility, and water uptake in the films. We also discuss a few theoretical models describing ion-polymer interactions. We hope that the guidelines we bring together in this review will help researchers perform a more comprehensive and consistent comparison of new materials and device designs, and they will be used to identify advances and opportunities to improve the device performance, progressing the field of organic bioelectronics.
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Affiliation(s)
- David Ohayon
- King Abdullah University of Science and Technology (KAUST), Biological and Environmental Science and Engineering Division, Organic Bioelectronics Laboratory, Thuwal 23955-6900, Saudi Arabia.
| | - Victor Druet
- King Abdullah University of Science and Technology (KAUST), Biological and Environmental Science and Engineering Division, Organic Bioelectronics Laboratory, Thuwal 23955-6900, Saudi Arabia.
| | - Sahika Inal
- King Abdullah University of Science and Technology (KAUST), Biological and Environmental Science and Engineering Division, Organic Bioelectronics Laboratory, Thuwal 23955-6900, Saudi Arabia.
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5
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Zhang Y, van Doremaele ERW, Ye G, Stevens T, Song J, Chiechi RC, van de Burgt Y. Adaptive Biosensing and Neuromorphic Classification Based on an Ambipolar Organic Mixed Ionic-Electronic Conductor. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2200393. [PMID: 35334499 DOI: 10.1002/adma.202200393] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 03/15/2022] [Indexed: 06/14/2023]
Abstract
Organic mixed ionic-electronic conductors (OMIECs) are central to bioelectronic applications such as biosensors, health-monitoring devices, and neural interfaces, and have facilitated efficient next-generation brain-inspired computing and biohybrid systems. Despite these examples, smart and adaptive circuits that can locally process and optimize biosignals have not yet been realized. Here, a tunable sensing circuit is shown that can locally modulate biologically relevant signals like electromyograms (EMGs) and electrocardiograms (ECGs), that is based on a complementary logic inverter combined with a neuromorphic memory element, and that is constructed from a single polymer mixed conductor. It is demonstrated that a small neuromorphic array based on this material effects high classification accuracy in heartbeat anomaly detection. This high-performance material allows for straightforward monolithic integration, which reduces fabrication complexity while also achieving high on/off ratios with excellent ambient p- and n-type stability in transistor performance. This material opens a route toward simple and straightforward fabrication and integration of more sophisticated adaptive circuits for future smart bioelectronics.
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Affiliation(s)
- Yanxi Zhang
- Microsystems, Department of Mechanical Engineering and Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, MB, 5600, The Netherlands
| | - Eveline R W van Doremaele
- Microsystems, Department of Mechanical Engineering and Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, MB, 5600, The Netherlands
| | - Gang Ye
- Center for Biomedical Optics and Photonics (CBOP) & College of Physics and Optoelectronic Engineering, Key Laboratory of Optoelectronic Devices and Systems, Shenzhen University, Shenzhen, 518060, P. R. China
- Stratingh Institute for Chemistry, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Tim Stevens
- Microsystems, Department of Mechanical Engineering and Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, MB, 5600, The Netherlands
| | - Jun Song
- Center for Biomedical Optics and Photonics (CBOP) & College of Physics and Optoelectronic Engineering, Key Laboratory of Optoelectronic Devices and Systems, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Ryan C Chiechi
- Stratingh Institute for Chemistry, University of Groningen, 9747 AG Groningen, The Netherlands
- Department of Chemistry, North Carolina State University, Raleigh, NC, 27695, USA
| | - Yoeri van de Burgt
- Microsystems, Department of Mechanical Engineering and Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, MB, 5600, The Netherlands
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