Jari Koskinen

Jari Koskinen
Aalto University · Department of Materials Science and Engineering

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161
Publications
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Publications

Publications (161)
Article
Full-text available
Nanocellulose has emerged as a promising green dispersant for carbon nanotubes (CNTs), and there is an increasing trend in developing nanocellulose/CNT hybrid materials for electrochemical detection of various small molecules. However, there have been very few comprehensive studies investigating the role of nanocellulosic material properties upon t...
Preprint
Nanocellulose has emerged as a promising green dispersant for carbon nanotubes (CNT), and there is an increasing trend in developing nanocellulose / CNT hybrid materials for electrochemical detection of various small molecules. However, there have been very few comprehensive studies investigating the role of nanocellulosic material properties upon...
Article
Full-text available
Linking structural and compositional features with the observed electrochemical performance is often ambiguous and sensitive to known and unknown impurities. Here an extensive experimental investigation augmented by computational analyses is linked to the electrochemical characterization of in situ nitrogen-doped tetrahedral amorphous carbon thin f...
Article
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Four different types of crystalline and fibrillar nanocellulosic materials with different functional groups (sulfate, carboxylate, amino-silane) are produced and used to disperse commercial multiwalled carbon nanotubes (MWCNT). Aqueous nanocellulose/MWCNT dispersions are drop-cast on tetrahedral amorphous carbon (ta-C) substrates to obtain highly s...
Article
Full-text available
Disposable single-use electrochemical sensor strips were used for quantitative detection of small concentrations of morphine in untreated capillary whole blood. Single-walled carbon nanotube (SWCNT) networks were fabricated on a polymer substrate to produce flexible, reproducible sensor strips with integrated reference and counter electrodes, compa...
Article
Full-text available
Successful deployment of carbon nanomaterials in many applications, such as sensing, energy storage, and catalysis, relies on the selection, synthesis, and tailoring of the surface properties. Predictive analysis of the behavior is difficult without detailed knowledge of the differences between various carbon nanomaterials and their surface functio...
Article
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A disposable electrochemical test strip for quantitative point-of-care (POC) determination of acetaminophen (paracetamol) in plasma and finger-prick whole blood was fabricated. The industrially scalable dry transfer process of single-walled carbon nanotubes (SWCNT) and screen-printing of silver was combined to produce integrated electrochemical tes...
Article
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Biofouling imposes a significant threat for sensing probes used in vivo. Antifouling strategies commonly utilize a protective layer on top the electrode but this may compromise performance of the electrode....
Article
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Oxycodone is a strong opioid frequently used as an analgesic. Although proven efficacious in the management of moderate to severe acute pain and cancer pain, the use of oxycodone imposes a risk of adverse effects such as addiction, overdose, and death. Fast and accurate determination of oxycodone blood concentration would enable personalized dosing...
Article
We prepare disposable single-walled carbon nanotube network electrodes for the detection of the potent opioid fentanyl, currently a leading cause for opioid overdose deaths in the USA. We show repeatable dry transfer of single-walled carbon nanotube (SWCNT) networks to produce robust electrodes. This process directly produces highly conductive SWCN...
Article
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Age structure in most developed countries is changing fast as the average lifespan is increasing significantly, calling for solutions to provide improved treatments for age-related neurological diseases and disorders. In order to address these problems, a reliable way of recording information about neurotransmitters from in vitro and in vivo applic...
Article
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Here, an unidentified type of micropillar growth is described at room temperature during conventional direct‐current magnetron sputtering (DC‐MS) deposition from a Li4Ti5O12+graphite sputter target under negative substrate bias and high operating pressure. These fabricated carbon–Li2O–TiO2 microstructures consisting of various Li4Ti5O12/Li2TiO3/Lix...
Article
In clinical settings, the dosing and differential diagnosis of the poisoning of morphine (MO) and codeine (CO) is challenging due to interindividual variations in metabolism. However, direct electrochemical detection of these analytes from biological matrices is inherently challenging due to interference from large concentrations of anions, such as...
Article
We introduce a composite membrane comprising of multi-walled carbon nanotubes (MWCNTs) dispersed in a matrix of sulfated nanofibrillar cellulose (SNFC) and Nafion®. The high negative charge densities of the SNFC and Nafion ionomers enhance the cationic selectivity of the composite. The composite is characterized by scanning electron (SEM) and trans...
Article
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Modification of the surface chemistry of carbon-based nanomaterials is often necessary in order to embrace their full potential. A wide variety of different post-fabrication treatments, such as acid, oxidizing plasma and heat treatments have been described in the literature. However, their specific effects on the materials surface chemistry is typi...
Article
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Pattern formation of pyrolyzed carbon (PyC) and tetrahedral amorphous carbon (ta-C) thin films were investigated at micro- and nanoscale. Micro- and nanopillars were fabricated from both materials, and their biocompatibility was studied with cell viability tests. Carbon materials are known to be very challenging to pattern. Here we demonstrate two...
Article
Nafion is widely used as a filtering membrane in electroanalytical applications to improve selectivity towards cations. However, the role of the thickness of Nafion on its electroanalytical performance is poorly understood. Furthermore, Nafion is often modified with additional elements without characterizing their influence on Nafion's filtering pr...
Article
High-resolution non-destructive chemical analysis of both bulk and surface of application-ready carbon nanomaterials is needed to connect the material properties to the observed performance. This is needed to enable application-specific tailoring of carbon nanomaterials. However, detailed studies of effects of oxidizing treatments on the chemical c...
Article
Undoped a‐C thin films were deposited with varying power density from 10 to 25 W/cm2 using unbalanced closed‐field magnetron sputtering (CFUBMS). The effect of power density on the physical and electrochemical properties was investigated by experimental characterization methods and atomistic simulations. XPS indicated that the films were composed m...
Article
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Application-specific carbon nanofibers grown from Pt-catalyst layers have been shown to be a promising material for biosensor development. Here we demonstrate immobilization of glutamate oxidase on them and their use for amperometric detection of glutamate at two different potentials. At −0.15 V vs. Ag/AgCl at concentrations higher than 100 μM the...
Article
Tramadol (TR) is a member of the opioid family and is widely used for pain treatment in clinical patient care. The analgesic effect of tramadol is induced primarily by its main metabolite O-desmethyltramadol (ODMT). Due to inter-individual differences in the TR metabolism to ODMT, the responses to TR vary highly between patients. Thus, a fast and s...
Article
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Iron-doped tetrahedral amorphous carbon thin films (Fe/ta-C) were deposited with varying iron content using a pulsed filtered cathodic vacuum arc system (p-FCVA). The aim of this study was to understand effects of iron on both the physical and electrochemical properties of the otherwise inert sp³-rich ta-C matrix. As indicated by X-ray photoelectro...
Article
Unmodified and multi-walled carbon nanotube (MWCNT) modified tetrahedral amorphous carbon (ta-C) films of 15 and 50 nm were investigated as potential in vivo sensor materials for the detection of dopamine (DA) in the presence of the main interferents, ascorbic acid (AA) and uric acid (UA). The MWCNTs were grown directly on ta-C by chemical vapor de...
Article
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We study the deposition of tetrahedral amorphous carbon (ta-C) films from molecular dynamics simulations based on a machine-learned interatomic potential trained from density-functional theory data. For the first time, the high sp3 fractions in excess of 85% observed experimentally are reproduced by means of computational simulation, and the deposi...
Article
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Removal of left-over catalyst particles from carbon nanomaterials is a significant scientific and technological problem. Here, we present the physical and electrochemical study of application-specific carbon nanofibers grown from Pt-catalyst layers. The use of Pt catalyst removes the requirement for any cleaning procedure as the remaining catalyst...
Article
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Corrosion protection of steel obtained with physical vapor deposition (PVD) coatings can be further improved by sealing the intrinsic pinholes with atomic layer deposition (ALD) coatings. In this work, the effect of surface wear on corrosion protection obtained by a hybrid PVD CrN/ALD Al2O3/TiO2 nanolaminate coating was studied. The samples were in...
Article
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A significant problem with implantable sensors is electrode fouling, which has been proposed as the main reason for biosensor failures in vivo. Electrochemical fouling is typical for dopamine (DA) as its oxidation products are very reactive and resulting polydopamine has a robust adhesion capability to virtually all types of surfaces. The degree of...
Article
We investigated the effect of anodic treatment of titanium/tetrahedral amorphous carbon electrodes on the electrochemical detection of morphine and paracetamol. The anodic treatment caused both oxidation of the carbon and, more importantly, exposure and oxidation of the underlying Ti layer. This treatment anodically shifted the oxidation potential...
Article
The non-stick properties of thin-film coatings on dental-restorative instruments were investigated by static contact-angle measurement using dental filler resin as well as by scanning electron microscopy of the amount of sticking dental restorative material. Furthermore, using a customized dipping measurement set-up, non-stick properties were evalu...
Article
Nanoscale amorphous carbon thin films with intrinsic Pt gradient show great promise as new electrode materials for electrochemical detection of hydrogen peroxide. Embedding the Pt particles in the carbon matrix during the fabrication process allows tighter integration than, for example, adding them after the fabrication on top of the substrate. Esp...
Article
In this study we present for the first time a tetrahedral amorphous carbon (ta-C) – partially reduced graphene oxide (PRGO) hybrid electrode nanomaterial platform for electrochemical sensing of dopamine (DA). Graphene oxide was synthesized with modified Hummer’s method. Before modification of ta-C by drop casting, partial reduction of the GO was ca...
Article
Full-text available
Complete removal of metal catalyst particles from carbon nanofibers (CNFs) and other carbon nanostructures is extremely difficult, and the envisioned applications may be compromised by the left-over impurities. To circumvent these problems, one should use, wherever possible, such catalyst materials that are meant to remain in the structure and have...
Article
Hydrogen peroxide (H2O2) is an important molecule produced in various enzymatic reactions. It is especially important in electrochemical, enzymatic biosensors detecting electroinactive analytes, such as glucose, cholesterol, and glutamate. Thus, there is strong need for materials that have high affinity for H2O2 oxidation or reduction as well as en...
Article
Atomic Layer Deposition (ALD) of Al2O3/TiO2 nanolaminate was applied to improve the sealing properties of CrN coating deposited with Physical Vapor Deposition (PVD) on high speed steel (HSS). The corrosion protection properties were explored with Linear Sweep Voltammetry and visual estimation. Nearly two orders of magnitude decrease in corrosion cu...
Article
Amorphous carbon based electrodes are very promising for electrochemical sensing applications. In order to better understand their structure-function relationship, the effect of film thickness on the electrochemical properties of tetrahedral amorphous carbon (ta-C) electrodes was investigated. ta-C thin films of 7, 15, 30, 50 and 100 nm were charac...
Article
Detonation Nanodiamonds (DNDs) are known to have sp³ core, sp² shell, small size (few nm) and are gaining importance as multi-functional nanoparticles. Diverse methods have been used to form composites, containing detonation nanodiamonds (DNDs) embedded in conductive and dielectric matrices for various applications. Here we show a method, wherein D...
Article
Amorphous carbon (a-C) films with varying oxygen content were deposited by closed-field unbalanced magnetron sputtering with the aim to understand the effect of oxygen on the structural and physical properties of the films and subsequently correlate these changes with electrochemical properties. The a-C films were characterized by transmission elec...
Article
Understanding the chemical nature of the surface of carbon nanofibers (CNF) is critical in assessing their fundamental properties and tailoring them for the right application. To gain such knowledge, we present here a detailed x-ray adsorption spectroscopy (XAS) study accompanied with high resolution transmission electron microscopy (TEM) micrograp...
Article
Single walled carbon nanotube networks (SWCNTNs) were coated by tetrahedral amorphous carbon (ta-C) to improve the mechanical wear properties of the composite film. The ta-C deposition was performed by using pulsed filtered cathodic vacuum arc method resulting in the generation of C+ ions in the energy range of 40–60 eV which coalesce to form a ta-...
Article
Detailed information about the physicochemical properties of a given surface is important in order to understand and predict the performance of materials in electrochemical applications. Here we present a detailed x-ray absorption spectroscopy study of two different tetrahedral amorphous-carbon (ta-C) thin films and their subsequent electrochemical...
Article
The wear properties of steel dental curettes coated with wear resistant Diamond Like Carbon (DLC) and metal nitride coatings deposited by Physical Vapor Deposition (PVD) were studied by using a customized mechanical device simulating motion and load of dental curettes against human teeth. The wear surfaces were studied by optical microscopy, Scanni...
Article
Carbon nanotubes are of wide interest due to their excellent properties such as tensile strength and electrical and thermal conductivity, but are not, when placed alone on a substrate, well resistant to mechanical wear. Diamond-like carbon (DLC), on the other hand, is widely used in applications due to its very good wear resistance. Combining the t...
Article
We present a detailed microstructural study comparing conventional carbon nanofibers (CNFs) and novel carbon hybrid CNF materials. The hybrid consists of CNFs grown on top of tetrahedral amorphous carbon (ta-C) thin films on silicon with nickel catalyst and Ti adhesion layers. The conventional CNFs were grown on silicon with nickel catalyst and Cr...
Article
Full-text available
Hydrogen peroxide is the product of various enzymatic reactions, and is thus typically utilized as the analyte in biosensors. However, its detection with conventional materials, such as noble metals or glassy carbon, is often hindered by slow kinetics and biofouling of the electrode. In this study electrochemical properties and suitability to perox...
Article
For every coating it is critical that the coatings are sufficiently durable to withstand practical applications and that the films adhere well enough to the substrate. In this paper the nanotribological, nanomechanical and interfacial properties of 15 - 100 nm thick atomic layer deposited (ALD) TiO2 coatings deposited at 110 - 300 °C were studied u...
Article
Carbon-based materials, such as diamond-like carbon (DLC), carbon nanofibers (CNFs), and carbon nanotubes (CNTs), are inherently interesting for neurotransmitter detection due to their good biocompatibility, low cost and relatively simple synthesis. In this paper, we report on new carbon-hybrid materials, where either CNTs or CNFs are directly grow...
Article
Single walled carbon nanotube network (SWCNTN) was coated by tetrahedral amorphous carbon (ta-C) using a pulsed Filtered Cathodic Vacuum Arc system to form a SWCNTN—ta-C composite film. The effects of SWCNTN areal coverage density and ta-C coating thickness on the composite film properties were investigated. X-Ray photoelectron spectroscopy measure...
Article
In this study we demonstrate a scalable and CMOS compatible synthesis of robust diamond-like carbon (DLC)–multi-walled carbon nanotube (MWCNT) hybrid electrodes. MWCNTs were grown directly on top of DLC thin film electrodes by utilizing Al/Co/Fe tri-layer catalyst structure at 550 °C. The structure of the hybrid material was characterized in detail...
Article
In this paper we present the results on the microstructure of a novel carbon hybrid material consisting of multi-walled carbon nanotubes (MWCNTs) grown on the top of tetrahedral amorphous carbon (ta-C) thin films on Si substrates with Ti adhesion promotion layer on top. It is shown here that: (i) the synthesis of the MWCNTs on top of ta-C layer at...
Article
The effect of surface finish with two types of carbon based coatings was evaluated in rolling contact twin disc tests. The surface finish grades represented the ground surface, and two polished surfaces providing average surface roughness values of Ra 0.128 µm and 0.030 µm. The twin disc test parameters were selected to represent the contact parame...
Article
Full-text available
In this paper we show that the electronic properties of ultrathin tetrahedral amorphous carbon (ta-C) films are heavily dependent on their thickness. By using scanning tunnelling spectroscopy, Raman spectroscopy, and conductive atomic force microscopy, it was found that a decrease of ta-C thickness from 30 to 7 nm leads to (i) a narrowing of the ba...
Article
Full-text available
Porous conductive carbon films are useful for application in fuel cells and biomedical sensors. Controllability of the porosity in conductive carbon films was investigated by using unbalanced magnetron sputtering (UBMS). Here, we show through porosity analysis and plasma diagnostics that carbon films can be tuned to have porosity ranging from amorp...
Chapter
Coatings and thin films grown by cathodic-arc and thermal-evaporation processes are reviewed. The state of the art has been obtained by using the latest available reviews and uppublications to September 2012. The main feature of cathodic-arc processes is the benefit to produce highly ionized plasma, enabling dense thin films with excellent adhesion...
Article
The friction and wear performance of 0-2 wt% graphene oxide (GO) dispersions in water were studied on diamond-like carbon vs. stainless steel contact by a pin-on-disc tribometer. The wear surfaces were characterized using contact profilometry, X-Ray spectroscopy, optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, and...
Article
The use of phage display to select material-specific peptides provides a general route towards modification and functionalization of surfaces and interfaces. However, a rational structural engineering of the peptides for optimal affinity is typically not feasible due to insufficient structure-function understanding. Here we investigate the influenc...
Article
The silica/graphene oxide (GO) composites powders of different compositions were synthesized by hydrothermal method. Composites were dispersed in ethylene glycol keeping the additive’s concentration constant (0.125 wt%). The lubricating properties of the dispersions were studied in steel–steel contact by pin-on-disc method. Tests were conducted at...
Conference Paper
Full-text available
In this paper, we present methodology for measuring mechanical properties of nano-coated micro- and nanostructures by pushing. The methods are demonstrated in four applications: interfacial mechanical properties of atomic layer deposited (ALD) thin films, strength of ALD-coated microfibers, adhesion and mechanical properties of thin films, and adhe...
Article
Carbon based materials have been frequently used to detect different biomolecules. For example high sp3 containing hydrogen free diamond-like carbon (DLC) possesses many properties that are beneficial for biosensor applications. Unfortunately, the sensitivities of the DLC electrodes are typically low. Here we demonstrate that by introducing topogra...