Recent improvements in sensor technology and applications can be partly attributed to the advancements in microand nanoscale fabrication processes and discovery of novel materials. The emergence of reliable and inexpensive methods of production of monolayer materials, such as graphene, has revealed the advantageous electronic properties which when utilized in sensory elements can significantly enhance response to the input signal. Hence, graphene-based sensory devices have been widely investigated as the exotic properties of the carbon nanomaterial allow for cost-efficient scalable production of highly sensitive transduction elements. Previous studies have shown successful detection of n-type dopants such as ammonia and low pH solution. As the amine group in amphetamine molecules is known to behave as an electron donor, in this study, graphene conductivity changes in response to exposure to amphetamine salt solutions were investigated.Graphene formed by chemical vapour deposition (CVD) was transferred onto SiO2 substrate with gold electrodes to form a resistive transducer. Observation of large intensity ratio of graphene characteristic 2D and G peaks as well as minimal defect peaks from Raman spectroscopy analysis proved the integrity of the carbon monolayer was maintained. The atomic force microscopy and resistance measurements results showed the storage of these sensory elements in ambient conditions results in adsorption of impurities which considerably influence the electronic properties of graphene. Upon exposure to amphetamine sulfate and amphetamine hydrochloride, conductivity decrease was detected as expected. Signal enhancement by excitation of 470nm light did not show a significant increase in response magnitude. However, the low reliability of sensor response limited further analysis of the chemical sensor signal. Non-selective sensor response to amphetamine can be detected, but improvements in device design are needed to minimize contamination of the graphene surface by ambient impurities and variations in the sensor system. / De senaste förbättringarna i sensorteknik och applikationer kan kopplas till framsteg inom framställningsprocesser berörande mikrooch nanoskala samt upptäckt av nya material. Framväxten av tillförlitliga och billiga produktionsmetoder av monoskiktmaterial, såsom grafen, har avslöjat de fördelaktiga elektroniska egenskaperna som när de används i sensoriska element och förbättrar signalresponsen till inputsignalen. Grafenbaserade sensoriska applicationer har undersökts allteftersom de exotiska egenskaperna hos kolbaserade nanomaterial möjliggör en kostnadseffektiv skalbara produktion av högkänsliga transduktionselement. Tidigare studier har framgångsrikt visat detektion av n-typ substanser såsom ammoniak och låg pH-lösning. Eftersom amingruppen i amfetaminmolekyler är känd för att verka som en elektrondonator, undersöktes i denna studie konduktivitetsändringar i grafen under exponering för amfetaminsaltlösningar.Grafen bildad genom kemisk ångavsättning (CVD) överfördes på Si02-substrat med guldelektroder för att bilda en resistiv omvandlare. Observation av intensitetförhållandet mellan de grafenkarakteristiska 2Doch G-topparna samt minimala defekttoppar från Ramanspektroskopianalysen visade att kolmonolagrets struktur upprätthölls. Resultaten av atomkraftmikroskopi och resistansmätningar visade att lagringen av de sensoriska element i normala omgivningsförhållanden resulterar i adsorption av föroreningar som avsevärt påverkar grafens elektroniska egenskaper. Vid exponering för amfetaminsulfat och amfetaminhydroklorid upptäcktes en förväntad konduktivitetsminskning. Signalförbättring genom excitation av 470nm-ljus visade inte en signifikant ökning av svarstyrkan. Den låga tillförlitligheten hos sensorn begränsade emellertid ytterligare analys av den kemiska sensorsignalen. Sensorns icke-selektiva svar på amfetamin kan detekteras, men förbättringar i enhetens konstruktion behövs för att minimera kontaminering av omgivande föroreningar på grafenytan och variationer i sensorsystemet.

Detta projekt var ett samarbete mellan Aplex Bio AB och Scilifelab. Projektets mål var att utveckla en molekylär diagnostisk panel med förmågan att detektera och diskriminera mellan 14 olika typer av patogener. Projektet innehåller 4 kapitel med fokus på olika mål. I första kapitlet utvecklades en metod för att karakterisera emissioner av fluorescerande nanopartikel kluster. Den första utvärderade metoden utnyttjade klick-kemi för att binda nanopartiklarna till makrostrukturer uppbyggda av amplifierat DNA. Den andra utvärderade metoden skapade aggregerade komplex av nanopartiklar med amplifierat DNA för att utvärdera partiklarnas emissioner. I kapitel 2 av projektet användes azid-funktionaliserade nanopartiklar levererade av Aplex Bio AB för att tvärbinda DBCO modifierade oligonukleotider. Sedan utvecklades en hybridiserings baserad metod för att kvantifiera relativa mängden oligonukleotider på partiklarna. Denna metod användes för att reproducerbart funktionalisera partiklar och utveckla nanopartikel-sonder som kan binda till DNA genom hybridisering. I kapitel 2 utvärderades även hur effektivt och specifikt de utvecklade nanopartikel-sonderna hybridiserar till DNA. I kapitel 3 utvärderades amplifiering av syntetiska ssDNA sekvenser valda från genetiska markörer av 14 patogener, DNA amplifierades med metoden RCA. Målet var att utvärdera specificiteten av amplifieringen. Specifik amplifiering av varje DNA sekvens i panelen var en förutsättning för att möjliggöra detektion och diskriminering av alla patogener i panelen. I kapitel 4 var målet att utveckla en kostnadseffektiv metod för att funktionalisera nanopartiklar med oligonukleotid sekvenser. För att göra detta användes DBCO-NHS-ester reagens och amin-modifierade oligonukleotider. Förverkligande av detta projekt skulle skapa en diagnostisk panel med potentialen att påverka det diagnostiska fältet på en global skala. När detta projekt är fullt utvecklat kan panelen modifieras för detektion av önskade DNA/RNA sekvenser vilket möjliggör ett mångfalt av applikationer, detta skulle göra panelen konkurrerande med dagens diagnostiska metoder då den kan användas i existerande mikroskopiuppsättningar. / This work was a collaboration between Aplex Bio AB and Scilifelab with the aim of developing a molecular assay capable of detecting and discriminating between 14 different pathogenic targets. There are 4 chapters with focus on different goals. In chapter one a method of evaluating emissions of fluorescent nanoparticle clusters was developed. The first approach of evaluating nanoparticle emissions was to utilize click chemistry to bind nanoparticles to macroscale structures of amplified DNA targets. The second evaluated approach was the formation of aggregated complexes of nanoparticles and amplified DNA targets. The second chapter of the thesis used azide functionalized nanoparticles supplied by Aplex Bio AB to utilize azide groups as crosslinkers and use them to functionalize the nanoparticles with DBCO oligos. A hybridization-based method was then developed to quantify relative oligo densities on the nanoparticles, enabling reproducible oligo functionalization of nanoparticles, producing nanoparticle probes that can bind to DNA. The final task of chapter 2 was evaluating the binding efficiency and specificity of the developed nanoparticle probes. The third chapter of the thesis evaluated amplification of synthetic ssDNA sequences corresponding to genetic markers of 14 pathogenic targets using RCA. The goal was to confirm specificity of chosen padlock probes and corresponding synthetic targets for each pathogen. Specific amplification of each target was a prerequisite to enable detecting and discriminating between the 14 pathogenic targets. In chapter 4 the goal was to develop a cost-effective method of oligo functionalization for nanoparticles. This chapter evaluated two main approaches of using DBCO-NHS-ester reagents to perform DBCO modification of amine-oligos. The realization of this work would develop an assay that has the potential to impact the field of diagnostics on a global scale. When fully developed, the molecular assay can be modified to detect any RNA/DNA targets which enables numerous applications, making the assay a competitive diagnostic tool which can be implemented in existing microscopy systems.

Conjugated polymers are novel organic electronic materials highly important for organic photovoltaic applications. Charge transport is one of the key properties which defines the performance of conjugated polymers in electronic devices. This work aims to explore the charge transport anisotropy in thin films of P3HT, one of the most common conjugated polymers. Using X-ray diffraction techniques and charge transport measurements, the relation between vertical charge transport through thin P3HT films and structure of the films was established. It was shown that particular orientations of crystalline domains of P3HT, namely face-on and chain-on, are beneficial for vertical charge transport. These orientations provide the efficient pathways for the charges to be transported vertically, either via π-π stacking interaction between the adjacent conjugated chains, or via the conjugated chain backbones. It was also demonstrated that particular orientations of crystallites are favourable for the formation of interconnected percolated pathways providing enhanced vertical charge transport across the film. Deposition of P3HT on most commonly used silicon substrates typically results in the formation of mostly edge-on orientation of crystallites which is unfavourable for vertical charge transport. Nanoimprint lithography was demonstrated as a powerful processing method for reorienting the edge-on crystalline domains of P3HT into chain-on (vertical) orientation. It is also shown that thin P3HT films with preferentially face-on orientations of crystallites can be deposited on graphene surface by spin coating. Using patterning of thin P3HT films by nanoimprint lithography, unprecedentedly high average vertical mobilities in the range of 3.1-10.6 cm2 V-1 s-1 were achieved in undoped P3HT. These results demonstrate that charge transport in thin films of a relatively simple and well-known conjugated polymer P3HT can be significantly improved using optimization of crystallinity,orientation of crystallites, polymer chain orientation and alignment in the films.

Thin film copper, indium, gallium, selenide (CIGS) solar cells are promising in the field of photovoltaic technology. To reduce material and fabrication cost, as well as increasing electrical properties of the cell, research is ongoing towards ultra-thin film solar cells (absorption layer thickness less than 500 nm). Ultra-thin CIGS solar cells has shown a decrease in interface recombination and improved optical properties when adding a rear contact passivation layer of aluminium oxide. In this work, the process of creating sub-micrometer features of a passivation layer using conventional optical lithography is investigated. To specify, the objective was to optimize the development conditions in the optical lithography process when fabricating equidistant line contacts in aluminium oxide with 800 nm feature size. It was found that line contacts with smaller feature sizes require longer development time, than line contacts with larger feature sizes. The experiments conducted showed that the pre-set development and exposure conditions used by the NOA group are not optimized for 800 nm or smaller line contacts. Further, for the optical lithography process, silicon substrates are not comparable with substrates of soda lime glass coated with molybdenum. Slight underdevelopment of a sample, showed line contacts smaller than the resolution of the laser used in the exposure – suggesting an alternative method of processing small line contacts with optical lithography.

Carbon nanotubes (CNTs) have gathered a lot of interest because of their extraordinary mechanical, electrical and thermal properties and have potential applications in a wide variety of areas such as material-reinforcement and nano-electronics. The properties of nanotubes are dependent on their diameter and methods for determining this using atomic force microscopy (AFM) in tapping mode assume that the measured height of the tubes represent the real diameter. Based on early, faulty calculations, the forces in tapping mode were assumed to be much lower than in contact mode, however it was later shown that forces in tapping mode can at point of impact rival the forces present in contact mode. This means that there is a potential risk of tube deformation during tapping mode measurements, resulting in incorrectly determined diameters. This work studies CNTs deposited on a silicon-substrate to analyze the effect of three common AFM settings (tapping frequency, free oscillation amplitude and setpoint) to determine their effect on measured CNT diameters and recommendations for choosing settings are given. / Kolnanorör har skapat mycket intresse på grund av sina extraordinära mekaniska, elektriska och termiska egenskaper och har lovande tillämpningar inom en mängd olika områden så som materialförstärkning och nanoelektronik. Kolnanorörens egenskaper påverkas kraftigt av deras diameter och de metoder som använder sig av atomkraftsmikroskopi(AFM) för att mäta diametern hos rören antar att den höjd-data man får fram är ett bra mått på den verkliga diametern hos rören. Baserat på tidiga, felaktiga beräkningar, antog man att kraften i ’tapping mode’ skulle vara mycket lägre än i ’contact mode’ vilket skulle leda till att man inte deformerar ytan man undersöker. Senare forskning visade att kraften mellan spets och prov kan vara lika stor eller rentutav större i tapping mode än i contact mode under det ögonblick då spetsen slår ner i provytan. Det medför att det finns en potentiell risk för att man deformerar kolnanorören när man mäter på dom vilket skulle resultera i att man får felaktiga värden på deras diametrar. Under det här projektet har kolnanorör som placerats på ett kisel-substrat undersökts för att analysera hur tre vanliga inställningar hos AFMet påverkar de erhållna värdena för diametern hos kolnanorören. De tre inställningarna som testats är svängnings-frekvensen, svängnings-amplituden i luft och börvärdet hos svängnings-amplituden.

Organic electrode materials represent an intriguing alternative to their inorganic counterparts due to their sustainable and environmental-friendly properties. Their plastic character allows for the realization of light-weight, versatile and disposable devices for energy storage. Conducting redox polymers (CRPs) are one type of the organic electrode materials involved, which consist of a π-conjugated polymer backbone and covalently attached redox units, the so-called pendant. The polymer backbone can provide conductivity while it is oxidized or reduced (i. e., p- or n-doped) and the concurrent redox chemistry of the pendant provides charge capacity. The combination of these two components enables CRPs to provide both high charge capacity and high power capability. This dyad polymeric framework provides a solution to the two main problems associated with organic electrode materials based on small molecules: the dissolution of the active material in the electrolyte, and the sluggish charge transport within the material. This thesis introduces a general synthetic strategy to obtain the monomeric CRPs building blocks, followed by electrochemical polymerization to afford the active CRPs material. The choice of pendant and of polymer backbone depends on the potential match between these two components, i.e. the redox reaction of the pendant and the doping of backbone occurring within the same potential region. In the thesis, terephthalate and polythiophene were selected as the pendant and polymer backbone respectively, to get access to low potential CRPs. It was found that the presence of a non-conjugated linker between polymer backbone and pendant is essential for the polymerizability of the monomers as well as for the preservation of individual redox activities. The resulting CRPs exhibited fast charge transport within the polymer film and low activation barriers for charge propagation. These low potential CRPs were designed as the anode materials for energy storage applications. The combination of redox active pendant as charge carrier and a conductive polymer backbone reveals new insights into the requirements of organic matter based electrical energy storage materials.

As part of the EU SmartVista project to develop a multi-modal wearable sensor for health diagnostics, field-effect transistor (FET) based biosensors were explored, with glucose as the analyte, and carbon nanotubes (CNTs) or monolayer MoS2 as the semiconducting sensing layer.  Numerous arrays of CNT-FETs and MoS2-FETs were fabricated by photolithographic methods and packaged as integrated circuits.  Functionalization of the sensing layer using linkers and enzymes was performed, and the samples were characterized by atomic force microscopy, scanning electron microscopy, optical microscopy, and electrical measurements. ON/OFF ratios of 102 p-type and < 102 n-type were acheived, respectively, and the work helped survey the viability of realizing such sensors in a wearable device. / EU Horizon 2020 - SmartVista (825114)

Identifying the protein content in a cell in a fast and reliable manner has become a relevant goal in the field of proteomics. This thesis computationally explores the potential for silicon nitride nanopores to sense and distinguish single miniproteins, which are small domains that promise to facilitate the systematic study of larger proteins. Sensing and identification of these biomolecules using nanopores happens by studying modulations in ionic current during translocation. The approach taken in this work was to study two miniproteins of similar geometry, using a cylindrical-shaped pore. I employed molecular mechanics to compare occupied pore currents computed based on the trajectory of ions. I further used density functional theory along with relative surface accessibility values to compute changes in interaction energies for single amino acids and obtain relative dwell times. While the protein remained inside the nanopore, I found no noticeable differences in the occupied pore currents of the two miniproteins for systems subject to 0.5 and 1.0 V bias voltages. Dwell times were estimated based on the translocation time of a protein that exhibits no interaction with the pore walls. I found that both miniproteins feel an attractive force to the pore wall and estimated their relative dwell times to differ by one order of magnitude. This means even in cases where two miniproteins are indistinguishable by magnitude changes in the ionic current, the dwell time might still be used to identify them. This work was an initial investigation that can be further developed to increase the accuracy of the results and be expanded to assess other miniproteins with the goal to aid future experimental work.

Low dimensional semiconductor structures are modeled using techniques from the field of many-body atomic physics. B-splines are used to create a one-particle basis, used to solve the more complex many-body problems. Details on methods such as the Configuration Interaction (CI), Many-Body Perturbation Theory (MBPT) and Coupled Cluster (CC) are discussed. Results from the CC singles and doubles method are compared to other high-precision methods for the circular harmonic oscillator quantum dot. The results show a good agreement for the energy of many-body states of up to 12 electrons. Properties of elliptical quantum dots, circular quantum dots, quantum rings and concentric quantum rings are all reviewed. The effects of tilted external magnetic fields applied to the elliptical dot are discussed, and the energy splitting between the lowest singlet and triplet states is explored for varying geometrical properties. Results are compared to experimental energy splittings for the same system containing 2 electrons.

The studies in the present thesis explored the feasibility of using nanocellulose-based filters in virus removal filtration of plasma-derived proteins.   In Paper I, two-step nanofiltration of commercially available human serum albumin (HSA) product, which was diluted to 10 g L-1 by phosphate buffer saline (PBS) and adjusted pH to 7.4, was performed to remove soluble protein aggregates and reduce filter fouling. The two-step filtration of HSA employed nanocellulose-based filters of varying thickness, i.e. 11 μm and 22 μm filters.  The removal of HSA aggregates during filtration through 11 μm pre-filters dramatically improves the flow properties of the 22 μm filter, enabling high protein throughput and high virus clearance. A distribution of pore sizes between 50 nm and 80 nm, which is present in the 11 μm filter and is absent in the 22 μm filter, plays a crucial part in removing the HSA aggregates. With respect to virus filtration, 1 bar constant trans-membrane pressure filtration shows poor removal ability of ΦX174 bacteriophage (28 nm), i.e., log10 reduction value (LRV) ≤ 3.75, while that at 3 bar and 5 bar achieves LRV[MOU1] [LW2]  > 5 model virus clearance and overall rapid filtration. Removal of protein aggregates during bioprocessing of HSA products is key to improving the filtration flux, which makes it possible to apply virus removal filtration for HSA to ensure its virus safety.   In Paper II, nanofiltration of human plasma-derived intravenous immuno-globulin (IVIG) intermediate (11.26 g L-1, pH 4.9) was carried out to demonstrate high product recovery and high model virus clearance. Virus removal filtration of industrial-grade human IVIG was achieved using 33μm filters at both low (60 Lm-2) and high (288 Lm-2) volumetric load. No changes in IVIG structure were detected and high product recovery was recorded. High virus clearance (LRV ≥ 5-6) was achieved for the small-size model viruses (ΦX174 and MS2 bacteriophages) during the load volume of 60 Lm-2. Side-by-side comparisons with commercial virus removal filters suggest that the nanocellulose-based filter paper presents great potential for industrial bioprocessing of plasma-derived IVIG.   In Paper III, process analytical technology (PAT) approach was employed to identify the critical filter parameters, e.g. thickness, basis weight, pore size, and flux, affecting model virus removal efficiency using filters produced by different hot presses.  The quality parameters were analyzed with ANOVA and Shewhart charts. Compared with other studied parameters, the hydraulic flux appears as the most relevant final product quality attribute of the nanocellulose-based filter paper to reflect the virus removal efficiency. In particular, a 15% higher flux may be associated with a 0.5-1.0 log10 reduced virus clearance (p=0.007). The results are highlight the importance of continued systematic studies in quality assurance using statistical process control tools  [MOU1]Define LRV  [LW2]Defined in the line above