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Clark KM, Nekoba DT, Viernes KL, Zhou J, Ray TR. Fabrication of high-resolution, flexible, laser-induced graphene sensors via stencil masking. Biosens Bioelectron 2024; 264:116649. [PMID: 39137522 PMCID: PMC11368413 DOI: 10.1016/j.bios.2024.116649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2024] [Revised: 07/19/2024] [Accepted: 08/07/2024] [Indexed: 08/15/2024]
Abstract
The advent of wearable sensing platforms capable of continuously monitoring physiological parameters indicative of health status have resulted in a paradigm shift for clinical medicine. The accessibility and adaptability of such portable, unobtrusive devices enables proactive, personalized care based on real-time physiological insights. While wearable sensing platforms exhibit powerful capabilities for continuously monitoring physiological parameters, device fabrication often requires specialized facilities and technical expertise, restricting deployment opportunities and innovation potential. The recent emergence of rapid prototyping approaches to sensor fabrication, such as laser-induced graphene (LIG), provides a pathway for circumventing these barriers through low-cost, scalable fabrication. However, inherent limitations in laser processing restrict the spatial resolution of LIG-based flexible electronic devices to the minimum laser spot size. For a CO2 laser-a commonly reported laser for device production-this corresponds to a feature size of ∼120 μm. Here, we demonstrate a facile, low-cost stencil-masking technique to reduce the minimum resolvable feature size of a LIG-based device from 120 ± 20 μm to 45 ± 3 μm when fabricated by CO2 laser. Characterization of device performance reveals this stencil-masked LIG (s-LIG) method yields a concomitant improvement in electrical properties, which we hypothesize is the result of changes in macrostructure of the patterned LIG. We showcase the performance of this fabrication method via production of common sensors including temperature and multi-electrode electrochemical sensors. We fabricate fine-line microarray electrodes not typically achievable via native CO2 laser processing, demonstrating the potential of the expanded design capabilities. Comparing microarray sensors made with and without the stencil to traditional macro LIG electrodes reveals the s-LIG sensors have significantly reduced capacitance for similar electroactive surface areas. Beyond improving sensor performance, the increased resolution enabled by this metal stencil technique expands capabilities for scalable fabrication of high-performance wearable sensors in low-resource settings without reliance on traditional fabrication pathways.
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Affiliation(s)
- Kaylee M Clark
- Department of Mechanical Engineering, University of Hawai'i at Mānoa, Honolulu, HI, 96822, USA
| | - Deylen T Nekoba
- Department of Mechanical Engineering, University of Hawai'i at Mānoa, Honolulu, HI, 96822, USA
| | - Kian Laʻi Viernes
- Department of Mechanical Engineering, University of Hawai'i at Mānoa, Honolulu, HI, 96822, USA
| | - Jie Zhou
- Department of Electrical Engineering, University of Hawai'i at Mānoa, Honolulu, HI, 96822, USA
| | - Tyler R Ray
- Department of Mechanical Engineering, University of Hawai'i at Mānoa, Honolulu, HI, 96822, USA; Department of Cell and Molecular Biology, John. A. Burns School of Medicine, University of Hawai'i at Mānoa, Honolulu, HI, 96813, USA.
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Miller C, Keattch O, Shergill RS, Patel BA. Evaluating diverse electrode surface patterns of 3D printed carbon thermoplastic electrochemical sensors. Analyst 2024; 149:1502-1508. [PMID: 38264850 DOI: 10.1039/d3an01592k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2024]
Abstract
Electrochemical sensing techniques rely on redox reactions taking place at the electrode surface. The configuration of this surface is of the utmost importance in the advancement of electrochemical sensors. The majority of previous electrode manufacturing methods, including 3D printing have produced electrodes with flat surfaces. There is a distinct potential for 3D printing to create intricate and distinctive electrode surface shapes. In the proposed work, 3D printed carbon black polylactic acid electrodes with nine different surface morphologies were made. These were compared to a flat surface electrode. To evaluate the performance of the electrodes, measurements were conducted in three different redox probes (ferrocene methanol, ferricyanide, and dopamine). Our findings highlighted that when electrodes were normalised for the geometric surface area of the electrode, the surface pattern of the electrode surface can impact the observed current and electron transfer kinetics. Electrodes that had a dome and flag pattern on the electrode surface showed the highest oxidation currents and had lower values for the difference between the anodic and cathodic peak current (ΔE). However, designs with rings had lower current values and higher ΔE values. These differences are most likely due to variations in the accessibility of conductive sites on the electrode surface due to the varying surface roughness of different patterned designs. Our findings highlight that when making electrodes using 3D printing, surface patterning of the electrode surface can be used as an effective approach to enhance the performance of the sensor for varying applications.
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Affiliation(s)
- Chloe Miller
- School of Applied Sciences, Brighton, BN2 4GJ, UK.
- Centre for Lifelong Health, Brighton, BN2 4GJ, UK
| | | | - Ricoveer S Shergill
- School of Applied Sciences, Brighton, BN2 4GJ, UK.
- Centre for Lifelong Health, Brighton, BN2 4GJ, UK
| | - Bhavik Anil Patel
- School of Applied Sciences, Brighton, BN2 4GJ, UK.
- Centre for Lifelong Health, Brighton, BN2 4GJ, UK
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McMahon CJ, Martinez B, Henry CS. Characterization of Factors Affecting Stripping Voltammetry on Thermoplastic Electrodes. JOURNAL OF THE ELECTROCHEMICAL SOCIETY 2023; 170:096507. [PMID: 37807977 PMCID: PMC10552556 DOI: 10.1149/1945-7111/acfa68] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
Thermoplastic carbon electrodes (TPEs) are an alternative form of carbon composite electrodes that have shown excellent electrochemical performance with applications in biological sensing. However, little has been done to apply TPEs to environmental sensing, specifically heavy metal analysis. The work here focuses on lead analysis and based on their electrochemical properties, TPEs are expected to outperform other carbon composite materials; however, despite testing multiple formulations, TPEs showed inferior performance. Detailed electrode characterization was conducted to examine the cause for poor lead sensing behavior. X-Ray photoelectron spectroscopy (XPS) was used to analyze the surface functional groups, indicating that acidic and alkaline functional groups impact lead electrodeposition. Further, scanning electron microscopy (SEM) and electrochemical characterization demonstrated that both the binder and graphite can influence the surface morphology, electroactive area, and electron kinetics.
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Affiliation(s)
| | | | - Charles S Henry
- Colorado State University, Fort Collins, Colorado 80523, USA
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Hernández-Rodríguez JF, López MÁ, Rojas D, Escarpa A. Digital manufacturing for accelerating organ-on-a-chip dissemination and electrochemical biosensing integration. LAB ON A CHIP 2022; 22:4805-4821. [PMID: 36342332 DOI: 10.1039/d2lc00499b] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Organ on-a-chip (OoC) is a promising technology that aims to recapitulate human body pathophysiology in a more precise way to advance in drug development and complex disease understanding. However, the presence of OoC in biological laboratories is still limited and mainly restricted to laboratories with access to cleanroom facilities. Besides, the current analytical methods employed to extract information from the organ models are endpoint and post facto assays which makes it difficult to ensure that during the biological experiment the cell microenvironment, cellular functionality and behaviour are controlled. Hence, the integration of real-time biosensors is highly needed and requested by the OoC end-user community to provide insight into organ function and responses to stimuli. In this context, electrochemical sensors stand out due to their advantageous features like miniaturization capabilities, ease of use, automatization and high sensitivity and selectivity. Electrochemical sensors have been already successfully miniaturized and employed in other fields such as wearables and point-of-care devices. We have identified that the explanation for this issue may be, to a large extent, the accessibility to microfabrication technologies. These fields employ preferably digital manufacturing (DM), which is a more accessible microfabrication approach regardless of funding and facilities. Therefore, we envision that a paradigm shift in microfabrication that adopts DM instead of the dominating soft lithography for the in-lab microfabrication of OoC devices will contribute to the dissemination of the field and integration of the promising real-time sensing.
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Affiliation(s)
- Juan F Hernández-Rodríguez
- Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering, University of Alcalá, Madrid, Spain.
| | - Miguel Ángel López
- Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering, University of Alcalá, Madrid, Spain.
- Chemical Engineering and Chemical Research Institute "Andres M. Del Río", University of Alcalá, Madrid, Spain
| | - Daniel Rojas
- Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering, University of Alcalá, Madrid, Spain.
| | - Alberto Escarpa
- Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering, University of Alcalá, Madrid, Spain.
- Chemical Engineering and Chemical Research Institute "Andres M. Del Río", University of Alcalá, Madrid, Spain
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Carbon composite thermoplastic electrodes integrated with mini-printed circuit board for wireless detection of calcium ions. ANAL SCI 2022; 38:1233-1243. [PMID: 35861910 DOI: 10.1007/s44211-022-00164-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2022] [Accepted: 07/06/2022] [Indexed: 11/01/2022]
Abstract
Here, a smartphone-based portable sensing system is developed for real-time detection of Ca2+ ions in a variety of biofluids. A solid-contact calcium-selective electrode (Ca2+-ISE) consisting of an ion-selective membrane (ISM), carbon black nanomaterial and polystyrene-graphite nanoplatelets as a solid contact was fabricated. The polyvinylchloride (PVC)-based ISM was optimized using different plasticizers and ion-exchangers. Under optimized conditions, the solid contacts were electrochemically characterized by electrochemical impedance spectroscopy (EIS), chronopotentiometric and potentiometric measurements. The Ca2+-ISE showed a Nernst response with a slope of 31.2 ± 0.6 mV/decade in the concentration range from 0.1 M to 10-4 M Ca2+ with a limit of detection (LOD) of 1.0 × 10-5 M. In addition, the ISEs exhibited good selectivity to Ca2+ ions over various interfering electrolytes and metabolites. The Ca2+-ISEs were applied in human urine and, artificial serum and cerebrospinal fluid samples. The ISEs showed good recoveries between 90 and 105%, indicating potential applicability of these electrodes in biological fluids. The portable lab-made potentiometer provides wireless data signaling and transmission to a smartphone and final Ca2+ concentration display due to its customized software. Therefore, the developed smartphone-based sensing platform offers low cost (< $25), rapid, user-friendly detection of Ca2+ especially in resource-limited areas.
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Ozer T, Henry CS. Microfluidic-based ion-selective thermoplastic electrode array for point-of-care detection of potassium and sodium ions. Mikrochim Acta 2022; 189:152. [PMID: 35322308 DOI: 10.1007/s00604-022-05264-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 03/06/2022] [Indexed: 10/18/2022]
Abstract
A microfluidic paper-based thermoplastic electrode (TPE) array has been developed for point-of-care detection of Na+ and K+ ions using a custom-made portable potentiometer. TPEs were fabricated using polystyrene as the binder and two different types of graphite to compare the electrode performance. The newly designed TPE array embedded in a polymethyl methacrylate chip consists of two working electrodes modified with carbon black nanomaterial and an ion-selective membrane, and an all-solid-state reference electrode modified with Ag/AgCl ink and poly(butyl methacrylate-co-methyl methacrylate) membrane via drop-casting. Ion-selective membrane compositions and conditioning steps were optimized. Under optimized conditions, ion-selective TPEs demonstrated fast response time (4 s) and good stability. The TPE array demonstrated a Nernstian behavior for K+ with a sensitivity of 59.2 ± 0.2 mV decade-1 and near-Nernstian response for Na+ with a sensitivity of 54.0 ± 1.1 mV decade-1 in the range 10-1 - 10-4 M and 1 - 10-3 M, respectively. The detection limits were 1 × 10-5 M and 1 × 10-4 M for K+ and Na+, respectively. In addition, a K+ and Na+ selective microfluidic paper-based analytical device (µPAD) was applied to artificial serum analysis and found in good agreement with average recoveries of 101.3% and 99.7%, respectively, suggesting that the developed ISE array is suitable for detection of sodium and potassium in complex matrix.
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Affiliation(s)
- Tugba Ozer
- Faculty of Chemical-Metallurgical Engineering, Department of Bioengineering, Yildiz Technical University, Istanbul, 34220, Turkey
- Department of Chemistry, Colorado State University, Fort Collins, CO, 80523, USA
| | - Charles S Henry
- Department of Chemistry, Colorado State University, Fort Collins, CO, 80523, USA.
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO, 80523, USA.
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Ozer T, Henry CS. All-solid-state potassium-selective sensor based on carbon black modified thermoplastic electrode. Electrochim Acta 2022. [DOI: 10.1016/j.electacta.2021.139762] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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McCord CP, Summers B, Henry C. Simultaneous Analysis of Ascorbic Acid, Uric Acid, and Dopamine at Bare Polystyrene Thermoplastic Electrodes. ChemElectroChem 2022. [DOI: 10.1002/celc.202101600] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | - Bali Summers
- Colorado State University Department of Chemistry UNITED STATES
| | - Charles Henry
- Colorado State University Chemistry 200 W. Lake St 80523 Fort Collins UNITED STATES
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Clark KM, Henry CS. Thermoplastic Electrode (TPE)‐based Enzymatic Glucose Sensor Using Polycaprolactone‐graphite Composites. ELECTROANAL 2021. [DOI: 10.1002/elan.202100446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Kaylee M. Clark
- Department of Chemistry Colorado State University 1872 Campus Delivery Fort Collins 80523 Colorado USA
| | - Charles S. Henry
- Department of Chemistry Colorado State University 1872 Campus Delivery Fort Collins 80523 Colorado USA
- School of Biomedical Engineering Colorado State University Fort Collins 80523 Colorado USA
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