Novel carbon materials and microstructures for electrochemical sensors

Joonas J. Heikkinen

Novel carbon materials and microstructures for electrochemical sensors

Julkaisun otsikon käännös: Uudenlaiset hiilimateriaalit ja mikrorakenteet sähkökemiallisiin sensoreihin

Joonas J. Heikkinen

Kemian ja materiaalitieteen laitos

Tutkimustuotos: Doctoral Thesis › Collection of Articles

Abstrakti

Hiilipohjaiset ohutkalvot ovat saaneet paljon huomiota, kun hiilinanoputket löydettiin vuonna 1991. Tämä laukaisi monimuotoisen hiilen laajamittaisen tutkimisen. Hiilen kaikkein tunnetuin muoto on timantti, jonka synteettistä versiota käytetään sovelluksissa, jotka vaativat suurta kulutuksenkestävyyttä. Hiilipohjaisilla materiaaleilla on kuitenkin paljon muitakin mahdollisuuksia. Tarjolla on laaja kirjo erilaisia hiilipohjaisia materiaaleja, joiden ominaisuuksia voidaan muovata käyttötarpeen mukaan. Tässä väitöskirjassa tutkittiin kolmea erilaista hiilen ohutkalvoa mikrovalmistuksen ja kuvioinnin näkökulmasta. Nämä valitut ohutkalvot olivat erityisesti sähköä johtavia, sillä niiden suorituskykyä arvioitiin elektrodimateriaalina monielektrodijärjestelmissä (MEA). Nämä kolme valittua materiaalia olivat nanohiili (nC), tetraedrinen amorfinen hiili (ta-C) ja pyrolyyttinen hiili (PyC). Mikrovalmistuksessa ja ohutkalvoteknologiassa on vain rajallinen määrä tekniikoita ja laitteistoja, joilla voidaan kuvioida hiilen ohutkalvoja. Tässä väitöskirjassa esitetään kuviointikeinot kaikille kolmelle tutkitulle hiilimateriaalille. Nanohiilen kohdalla käytettiin plasmaetsausta, ta-C kalvot kuvioitiin lift-off -tekniikalla ja PyC kuvioitiin fotoresistinä ennen pyrolyysiä. Useimmat hiilimateriaalit ovat luonnostaan bioyhteensopivia ilman minkäänlaisia pinnoituksia. Näitä kolmea hiilimateriaalia käytettiin sähkökemiallisissa mittauksissa biologisten analyyttien tai hermovälittäjäaineiden, kuten dopamiinin, vähäisen määrän havaitsemiseen. Sähkökemian näkökulmasta hiili on houkutteleva materiaali, sillä sen ominaisuuksiin kuuluu leveä potentiaali-ikkuna, joka mahdollistaa usean analyytin mittauksen samaan aikaan. PyC ja ta-C tuottivat hyviä tuloksia dopamiinin havainnoinnissa keinotekoisista liuoksista, mutta kehitystyötä tarvitaan vielä häiritsevien molekyylien ja epäpuhtauksien erottelemiseen. Näitä kolmea hiilimateriaalia käytettiin monielektrodijärjestelmissä, jotka rakentuvat useista lähellä toisiaan olevista mikroelektrodeista. MEA-alustoilla voidaan mitata hermosolupopulaatioiden välistä viestintää, seurata aivoleikkeiden aktiivisuutta tai havainnoida biologisten analyyttien erittäin vähäisiä pitoisuuksia. Tässä työssä esitellään biologisia mittauksia vain nanohiili-MEA alustalla (aivoleikkeillä). PyC ja ta-C materiaaleista saatiin onnistuneesti valmistettua MEA-alustoja, mutta niiden suorituskykyä testattiin vain alustavissa kokeissa.

Julkaisun otsikon käännös	Uudenlaiset hiilimateriaalit ja mikrorakenteet sähkökemiallisiin sensoreihin
Alkuperäiskieli	Englanti
Pätevyys	Tohtorintutkinto
Myöntävä instituutio	Aalto-yliopisto
Valvoja/neuvonantaja	Franssila, Sami, Vastuuprofessori Jokinen, Ville, Ohjaaja
Kustantaja	Aalto University
Painoksen ISBN	978-952-64-0550-6
Sähköinen ISBN	978-952-64-0551-3
Tila	Julkaistu - 2021
OKM-julkaisutyyppi	G5 Artikkeliväitöskirja

Tutkimusalat

mikrovalmistus
hiili
pyrolyysi
monielektrodijärjestelmät

Pääsy asiakirjaan

http://urn.fi/URN:ISBN:978-952-64-0551-3

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@phdthesis{d138517fda3a4259a3195cbbcd3af0a4,

title = "Novel carbon materials and microstructures for electrochemical sensors",

abstract = "Carbon thin films have gained a lot of attention since the discovery of carbon nanotubes in 1991, which ignited widespread research on the many forms of carbon. The most well-known form of carbon is diamond, and its synthetic version has been adopted in applications that require high wear resistance. However, carbonaceous materials have a lot more potential than just that. There is a broad spectrum of carbonaceous materials available which properties can be tailored according to need. In this thesis, three different carbon thin films were studied from the microfabrication and patterning perspective. These selected thin films were especially electrically conductive as their performance was studied as electrode material in multielectrode arrays (MEA). These three materials were nanocarbon (nC), tetrahedral amorphous carbon (ta-C), and pyrolytic carbon (PyC). In microfabrication and thin film technologies, the methods and equipment for carbon thin film patterning are limited. This thesis presents patterning methods for all three studied carbon materials. The nC film was plasma etched, the ta-C film was patterned with lift-off, and PyC was patterned while it was still photoresist before pyrolysis. Most carbon materials are naturally biocompatible without any additional surface coatings. These three materials were used in electrochemical measurements to detect the minor presence of neurotransmitters like dopamine or other biological analytes. From an electrochemistry point of view, carbon is an appealing material as it exhibits a wide potential window that allows the measurement of multiple analytes simultaneously. PyC and ta-C show promising results in dopamine detection from bulk concentrations, but there is still a need for improvement if interfering molecules and impurities are present. These three carbon materials were utilized in multielectrode arrays, which are formed of many microelectrodes close to each other. MEA devices can be used to follow the signaling between neuronal cultures, follow the activity of brain slices, or measure even the minuscule concentration of biological analytes. This thesis presents biological measurements only for nC-MEA (with brain slice). PyC and ta-C materials were successfully implemented in MEAs, but their performance was only tested in preliminary experiments.",

keywords = "microfabrication, carbon, pyrolysis, multielectrode arrays, mikrovalmistus, hiili, pyrolyysi, monielektrodij{\"a}rjestelm{\"a}t, microfabrication, carbon, pyrolysis, multielectrode arrays",

author = "Heikkinen, {Joonas J.}",

year = "2021",

language = "English",

isbn = "978-952-64-0550-6",

series = "Aalto University publication series DOCTORAL DISSERTATIONS",

publisher = "Aalto University",

number = "142",

address = "Finland",

school = "Aalto University",

}

TY - THES

T1 - Novel carbon materials and microstructures for electrochemical sensors

AU - Heikkinen, Joonas J.

PY - 2021

Y1 - 2021

N2 - Carbon thin films have gained a lot of attention since the discovery of carbon nanotubes in 1991, which ignited widespread research on the many forms of carbon. The most well-known form of carbon is diamond, and its synthetic version has been adopted in applications that require high wear resistance. However, carbonaceous materials have a lot more potential than just that. There is a broad spectrum of carbonaceous materials available which properties can be tailored according to need. In this thesis, three different carbon thin films were studied from the microfabrication and patterning perspective. These selected thin films were especially electrically conductive as their performance was studied as electrode material in multielectrode arrays (MEA). These three materials were nanocarbon (nC), tetrahedral amorphous carbon (ta-C), and pyrolytic carbon (PyC). In microfabrication and thin film technologies, the methods and equipment for carbon thin film patterning are limited. This thesis presents patterning methods for all three studied carbon materials. The nC film was plasma etched, the ta-C film was patterned with lift-off, and PyC was patterned while it was still photoresist before pyrolysis. Most carbon materials are naturally biocompatible without any additional surface coatings. These three materials were used in electrochemical measurements to detect the minor presence of neurotransmitters like dopamine or other biological analytes. From an electrochemistry point of view, carbon is an appealing material as it exhibits a wide potential window that allows the measurement of multiple analytes simultaneously. PyC and ta-C show promising results in dopamine detection from bulk concentrations, but there is still a need for improvement if interfering molecules and impurities are present. These three carbon materials were utilized in multielectrode arrays, which are formed of many microelectrodes close to each other. MEA devices can be used to follow the signaling between neuronal cultures, follow the activity of brain slices, or measure even the minuscule concentration of biological analytes. This thesis presents biological measurements only for nC-MEA (with brain slice). PyC and ta-C materials were successfully implemented in MEAs, but their performance was only tested in preliminary experiments.

AB - Carbon thin films have gained a lot of attention since the discovery of carbon nanotubes in 1991, which ignited widespread research on the many forms of carbon. The most well-known form of carbon is diamond, and its synthetic version has been adopted in applications that require high wear resistance. However, carbonaceous materials have a lot more potential than just that. There is a broad spectrum of carbonaceous materials available which properties can be tailored according to need. In this thesis, three different carbon thin films were studied from the microfabrication and patterning perspective. These selected thin films were especially electrically conductive as their performance was studied as electrode material in multielectrode arrays (MEA). These three materials were nanocarbon (nC), tetrahedral amorphous carbon (ta-C), and pyrolytic carbon (PyC). In microfabrication and thin film technologies, the methods and equipment for carbon thin film patterning are limited. This thesis presents patterning methods for all three studied carbon materials. The nC film was plasma etched, the ta-C film was patterned with lift-off, and PyC was patterned while it was still photoresist before pyrolysis. Most carbon materials are naturally biocompatible without any additional surface coatings. These three materials were used in electrochemical measurements to detect the minor presence of neurotransmitters like dopamine or other biological analytes. From an electrochemistry point of view, carbon is an appealing material as it exhibits a wide potential window that allows the measurement of multiple analytes simultaneously. PyC and ta-C show promising results in dopamine detection from bulk concentrations, but there is still a need for improvement if interfering molecules and impurities are present. These three carbon materials were utilized in multielectrode arrays, which are formed of many microelectrodes close to each other. MEA devices can be used to follow the signaling between neuronal cultures, follow the activity of brain slices, or measure even the minuscule concentration of biological analytes. This thesis presents biological measurements only for nC-MEA (with brain slice). PyC and ta-C materials were successfully implemented in MEAs, but their performance was only tested in preliminary experiments.

KW - microfabrication

KW - carbon

KW - pyrolysis

KW - multielectrode arrays

KW - mikrovalmistus

KW - hiili

KW - pyrolyysi

KW - monielektrodijärjestelmät

KW - microfabrication

KW - carbon

KW - pyrolysis

KW - multielectrode arrays

M3 - Doctoral Thesis

SN - 978-952-64-0550-6

T3 - Aalto University publication series DOCTORAL DISSERTATIONS

PB - Aalto University

ER -

Novel carbon materials and microstructures for electrochemical sensors

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