1,720,962 research outputs found
Advances in Additive Manufacturing of Organic Electrochemical Transistors
No full textTechnological advances and applications of printed electronic devices rely on novel organic semiconductor (OSC) materials and cutting-edge advanced manufacturing technologies. A growing number of solution- processable organic electronic materials has paved the way towards cost- efficient fabrication techniques, fostering the growth and emergence of printed electronics research in recent decades. Organic semiconductor materials are unique because of mixed ionic and electronic transport of charges that may translate biological signals into electrical ones or vice versa. The organic electrochemical transistor (OECT) is a type of transistor where the active material (channel) is made of an organic mixed ionic-electronic conductor (OMIEC). Since OECTs may serve as organic bioelectronic devices that encompass high ionic and electronic conductivity, they also represent a groundbreaking technology by forming communication channels between living systems and external electronic circuits used for recording. Highly conductive and stable OMIECs, sustainable solvents for ink formulations, bio-based substrates, new device architectures and redefined manufacturing strategies are the keys that unlock highly sensitive OECT-based (bio)sensor devices and OECT-based electronic circuits with high gain and low power consumption. This dissertation explores and unveils the effects of different additive manufacturing strategies, channel materials, ink formulations and device architectures on the performance and applications of all-printed OECT devices. The key findings of this thesis are summarized in four first-authored scientific journal articles. In the first article, we redefined the manufacturing approach to create high performance all-printed OECTs exhibiting very short switching times; this approach was further verified by printing OECT-based inverters operating at a frequency beyond 100 Hz and five-stage ring oscillators. In the second article, we developed an all-printed sensor platform by combining highly sensitive OECT and piezoelectric sensor devices on a tattoo paper substrate for seamless integration with the skin, enabling the detection of radial pulse waves. In the third article, a screen printed OECT was integrated into capillary 3D-printed microfluidics with the goal of ion sensing, thereby forming an additively manufactured sensor platform. The fourth article demonstrates, for the first time, vertically stacked accumulation mode pgBTTT-based OECTs manufactured by combining screen and inkjet printing technologies. By selecting a non-toxic and biodegradable solvent (Cyrene) instead of chloroform in the preparation of the pgBTTT-based inkjet ink formulation, we move towards more sustainable OECTs. The resulting all-printed pgBTTT-based OECTs exhibited high figures of merit, short switching times and good operational stability in an ambient environment. Finally, this dissertation offers insights and perspectives on the rational use of printing technologies, channel materials (p-type), sustainable ink formulations, and device architectures to enable further progress of all-printed OECT-based (bio)sensors, amplifiers and complementary logic circuits for various (bio)electronic applications. Teknologiska framsteg och tillämpningar inom tryckt elektronik är beroende av nya organiska halvledarmaterial och avancerad tillverkningsteknik. Ett stort urval av organiska elektroniska material och kostnadseffektiva additiva tillverkningstekniker har möjliggjort framväxten av forskningsområdet tryckt elektronik under de senaste decennierna. Organiska halvledarmaterial är unika, dels för att de kan processas från lösning, men också på grund av att kombinationen av både jon- och elektrontransport kan användas för att översätta biologiska signaler till elektriska, eller vice versa. En organisk elektrokemisk transistor (OECT) är en typ av transistor där det aktiva kanalmaterialet är baserat på ett organiskt material som leder både joner och elektroner, t.ex. en konjugerad polymer. Tack vare detta kan OECTs användas inom bioelektroniska tillämpningar, som banbrytande teknik för att underlätta kommunikationen mellan levande system och elektronisk mätutrustning. Organiska halvledare med hög ledningsförmåga och bra stabilitet, miljövänliga lösningsmedel för bläckformuleringar, biobaserade substrat, nya komponentstrukturer och nytänkande kring tillverkningsstrategier är viktiga parametrar för att erhålla hög känslighet i OECT-baserade (bio)sensorer samt OECT-baserade elektroniska kretsar med hög förstärkning och låg effektförbrukning. Denna avhandling syftar till att utforska och förstå hur olika additiva tillverkningsstrategier, material, bläckformuleringar och komponentstrukturer påverkar prestandan hos helt tryckta OECTs, och i vilka tillämpningsområden de kan användas. De viktigaste resultaten av detta arbete sammanfattas i fyra artiklar. I den första artikeln kombinerade vi två olika tryckteknologier för att skapa högpresterande heltryckta OECTs med korta switchtider; detta tillvägagångssätt verifierades också genom att trycka ringoscillatorer samt OECT-baserade inverterare som kunde drivas vid en frekvens på över 100 Hz. I den andra artikeln utvecklade vi helt tryckta sensorplatt-formar genom att kombinera OECTs med hög känslighet och piezoelektriska sensorer på tatueringspapper, för att skapa bästa möjliga kontakt med huden. Den screentryckta piezoelektriska sensorn användes för att detektera och omvandla mekaniska vibrationer från hjärtslagen till elektriska signaler, som i sin tur användes som insignal till en förstärkarkomponent i form av en tryckt OECT. I den tredje artikeln integrerades en screentryckt OECT i en mikrofluidikkrets, med målet att detektera joner i en additivt tillverkad sensorplattform. Den 3D-skrivna kapillära mikrofluidikkretsen modifierades med skräddarsydda mönster av inkjettryckta hydrofila filmer för att skapa ett automatiserat flöde av flera olika vätskor. Den hydrofila egenskapen bibehölls i minst 6 månader och ingen extern utrustning krävdes för att kontrollera det sekventiella flödet av vätskor. Den fjärde artikeln visar en pgBTTT-baserad OECT tillverkad genom att kombinera screen- och inkjettryckning. Den organiska halvledande po-lymeren pgBTTT användes som det aktiva kanalmaterialet, vilket resulterade i en anrikningstransistor där de ingående materialen trycktes ovanpå varandra. Dessutom användes ett ofarligt och biologiskt nedbryt-bart lösningsmedel (Cyrene) i det pgBTTT-baserade inkjetbläcket, vilket är ett viktigt steg i arbetet mot mer hållbara elektroniska komponenter. Sammanfattningsvis tillhandahåller denna doktorsavhandling insikter och perspektiv på användningen av tryckteknik, materialval, hållbara bläckformuleringar och komponentstrukturer för att möjliggöra ytterligare utveckling av helt tryckta OECT-baserade (bio)sensorer, förstärkarkretsar och komplementära logikkretsar för olika (bio)elektroniska applikationer.
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Toward Sustainability in All-Printed Accumulation Mode Organic Electrochemical Transistors
Full text linkAbstract This study reports on the first all-printed vertically stacked organic electrochemical transistors (OECTs) operating in accumulation mode; the devices, relying on poly([4,4?-bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-2,2?-bithiophen-5,5?-diyl]-alt-[thieno[3,2-b]thiophene-2,5-diyl]) (pgBTTT) as the active channel material, are fabricated via a combination of screen and inkjet printing technologies. The resulting OECTs (W/L ≈5) demonstrate good switching performance; gm, norm ≈13 mS cm?1, µC* ≈21 F cm?1 V?1 s?1, ON?OFF ratio > 104 and good cycling stability upon continuous operation for 2 h. The inkjet printing process of pgBTTT is established by first solubilizing the polymer in dihydrolevoglucosenone (Cyrene), a non-toxic, cellulose-derived, and biodegradable solvent. The resulting ink formulations exhibit good jettability, thereby providing reproducible and stable p-type accumulation mode all-printed OECTs with high performance. Besides the environmental and safety benefits of this solvent, this study also demonstrates the assessment of how the solvent affects the performance of spin-coated OECTs, which justifies the choice of Cyrene as an alternative to commonly used harmful solvents such as chloroform, also from a device perspective. Hence, this approach shows a new possibility of obtaining more sustainable printed electronic devices, which will eventually result in all-printed OECT-based logic circuits operating in complementary mode.This project received funding from the European Union's Horizon 2020 research and innovation program under grant agreement no. 964677 (MITICS). The authors would like to thank Jessica Åhlin for valuable electrolyte discussions. A.M. and P.A.E. thank Vinnova for financial support (grant agreement no. 2023-01337). W.M., L.B., and A.G. thank the FWO Vlaanderen for financial support (WEAVE project G025922N and Ph.D. grant 1S70122N)</p
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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