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Seaton BT, Heien ML. Biocompatible reference electrodes to enhance chronic electrochemical signal fidelity in vivo. Anal Bioanal Chem 2021; 413:6689-6701. [PMID: 34595560 DOI: 10.1007/s00216-021-03640-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 08/27/2021] [Accepted: 08/30/2021] [Indexed: 12/17/2022]
Abstract
In vivo electrochemistry is a vital tool of neuroscience that allows for the detection, identification, and quantification of neurotransmitters, their metabolites, and other important analytes. One important goal of in vivo electrochemistry is a better understanding of progressive neurological disorders (e.g., Parkinson's disease). A complete understanding of such disorders can only be achieved through a combination of acute (i.e., minutes to hours) and chronic (i.e., days or longer) experimentation. Chronic studies are more challenging because they require prolonged implantation of electrodes, which elicits an immune response, leading to glial encapsulation of the electrodes and altered electrode performance (i.e., biofouling). Biofouling leads to increased electrode impedance and reference electrode polarization, both of which diminish the selectivity and sensitivity of in vivo electrochemical measurements. The increased impedance factor has been successfully mitigated previously with the use of a counter electrode, but the challenge of reference electrode polarization remains. The commonly used Ag/AgCl reference electrode lacks the long-term potential stability in vivo required for chronic measurements. In addition, the cytotoxicity of Ag/AgCl adversely affects animal experimentation and prohibits implantation in humans, hindering translational research progress. Thus, a move toward biocompatible reference electrodes with superior chronic potential stability is necessary. Two qualifying materials, iridium oxide and boron-doped diamond, are introduced and discussed in terms of their electrochemical properties, biocompatibilities, fabrication methods, and applications. In vivo electrochemistry continues to advance toward more chronic experimentation in both animal models and humans, necessitating the utilization of biocompatible reference electrodes that should provide superior potential stability and allow for unprecedented chronic signal fidelity when used with a counter electrode for impedance mitigation.
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Affiliation(s)
- Blake T Seaton
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85721, USA
| | - Michael L Heien
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85721, USA.
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Zherikova KV, Makarenko AM, Karakovskaya KI, Zelenina LN, Sysoev SV, Vikulova ES, Morozova NB. Thermodynamic Study of Iridium(I) Complexes as a Basis for Chemical Gas-Phase Deposition Technology. RUSS J GEN CHEM+ 2021. [DOI: 10.1134/s1070363221100108] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Li Z, Tian Y, Teng C, Cao H. Recent Advances in Barrier Layer of Cu Interconnects. MATERIALS (BASEL, SWITZERLAND) 2020; 13:E5049. [PMID: 33182434 PMCID: PMC7664900 DOI: 10.3390/ma13215049] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 11/06/2020] [Accepted: 11/06/2020] [Indexed: 01/31/2023]
Abstract
The barrier layer in Cu technology is essential to prevent Cu from diffusing into the dielectric layer at high temperatures; therefore, it must have a high stability and good adhesion to both Cu and the dielectric layer. In the past three decades, tantalum/tantalum nitride (Ta/TaN) has been widely used as an inter-layer to separate the dielectric layer and the Cu. However, to fulfill the demand for continuous down-scaling of the Cu technology node, traditional materials and technical processes are being challenged. Direct electrochemical deposition of Cu on top of Ta/TaN is not realistic, due to its high resistivity. Therefore, pre-deposition of a Cu seed layer by physical vapor deposition (PVD) or chemical vapor deposition (CVD) is necessary, but the non-uniformity of the Cu seed layer has a devastating effect on the defect-free fill of modern sub-20 or even sub-10 nm Cu technology nodes. New Cu diffusion barrier materials having ultra-thin size, high resistivity and stability are needed for the successful super-fill of trenches at the nanometer scale. In this review, we briefly summarize recent advances in the development of Cu diffusion-proof materials, including metals, metal alloys, self-assembled molecular layers (SAMs), two-dimensional (2D) materials and high-entropy alloys (HEAs). Also, challenges are highlighted and future research directions are suggested.
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Affiliation(s)
- Zhi Li
- Institute of Marine Biomedicine, Shenzhen Polytechnic, Shenzhen 518055, China;
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing 211816, China
- National Laboratory of Solid State Microstructures, College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China;
| | - Ye Tian
- National Laboratory of Solid State Microstructures, College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China;
| | - Chao Teng
- Institute of Marine Biomedicine, Shenzhen Polytechnic, Shenzhen 518055, China;
| | - Hai Cao
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing 211816, China
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4
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Freakley SJ, Ruiz-Esquius J, Morgan DJ. The X-ray photoelectron spectra of Ir, IrO2
and IrCl3
revisited. SURF INTERFACE ANAL 2017. [DOI: 10.1002/sia.6225] [Citation(s) in RCA: 167] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- S. J. Freakley
- Cardiff Catalysis Institute; School of Chemistry, Cardiff University; Park Place Cardiff CF10 3AT UK
| | - J. Ruiz-Esquius
- Cardiff Catalysis Institute; School of Chemistry, Cardiff University; Park Place Cardiff CF10 3AT UK
| | - D. J. Morgan
- Cardiff Catalysis Institute; School of Chemistry, Cardiff University; Park Place Cardiff CF10 3AT UK
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Wu WP, Chen ZF. Micropore formation mechanism in iridium coating after high-temperature treatment. SURF INTERFACE ANAL 2016. [DOI: 10.1002/sia.5986] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Wang-ping Wu
- School of Mechanical Engineering; Changzhou University; Changzhou 213164 China
- College of Material Science and Technology; Nanjing University of Aeronautics and Astronautics; Nanjing 210016 China
| | - Zhao-feng Chen
- College of Material Science and Technology; Nanjing University of Aeronautics and Astronautics; Nanjing 210016 China
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Kahk JM, Poll CG, Oropeza FE, Ablett JM, Céolin D, Rueff JP, Agrestini S, Utsumi Y, Tsuei KD, Liao YF, Borgatti F, Panaccione G, Regoutz A, Egdell RG, Morgan BJ, Scanlon DO, Payne DJ. Understanding the electronic structure of IrO2 using hard-X-ray photoelectron spectroscopy and density-functional theory. PHYSICAL REVIEW LETTERS 2014; 112:117601. [PMID: 24702416 DOI: 10.1103/physrevlett.112.117601] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Indexed: 05/27/2023]
Abstract
The electronic structure of IrO2 has been investigated using hard x-ray photoelectron spectroscopy and density-functional theory. Excellent agreement is observed between theory and experiment. We show that the electronic structure of IrO2 involves crystal field splitting of the iridium 5d orbitals in a distorted octahedral field. The behavior of IrO2 closely follows the theoretical predictions of Goodenough for conductive rutile-structured oxides [J. B. Goodenough, J. Solid State Chem. 3, 490 (1971).
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Affiliation(s)
- J M Kahk
- Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
| | - C G Poll
- Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
| | - F E Oropeza
- Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
| | - J M Ablett
- Synchrotron SOLEIL, L'Orme des Merisiers, BP 48 Saint-Aubin, 91192 Gif-sur-Yvette, France
| | - D Céolin
- Synchrotron SOLEIL, L'Orme des Merisiers, BP 48 Saint-Aubin, 91192 Gif-sur-Yvette, France
| | - J-P Rueff
- Synchrotron SOLEIL, L'Orme des Merisiers, BP 48 Saint-Aubin, 91192 Gif-sur-Yvette, France
| | - S Agrestini
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzerstr. 40, 01187 Dresden, Germany
| | - Y Utsumi
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzerstr. 40, 01187 Dresden, Germany
| | - K D Tsuei
- National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu 30077, Taiwan
| | - Y F Liao
- National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu 30077, Taiwan
| | - F Borgatti
- Consiglio Nazionale delle Ricerche, Istituto per lo Studio dei Materiali Nanostrutturati (CNR-ISMN), via P. Gobetti n.101, I-40129 Bologna, Italy
| | - G Panaccione
- Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, in Area Science Park, S.S.14, Km 163.5, I-34149 Trieste, Italy
| | - A Regoutz
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom
| | - R G Egdell
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom
| | - B J Morgan
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
| | - D O Scanlon
- University College London, Kathleen Lonsdale Materials Chemistry, Department of Chemistry, 20 Gordon Street, London WC1H 0AJ, United Kingdom and Diamond Light Source Ltd., Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - D J Payne
- Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
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