Many experts agree that the future of wearables is smart fabrics and wearable electronics will be directly embedded in our clothes in the form of microdevices, yarns and fibers rather than external gadgets. The next transition from the classical flexible but rigid wearable electronics to the new textile-based one, is laying the foundations of a new technological field that was recently termed as “Textronic”. If one hand embedded textile-based sensors for human health monitoring gained tremendous attention because of their potentiality to bring healthcare to a next level accomplishing the new paradigm of predictive diagnostic approach, all of this microdevice necessarily require the development of a new highly miniaturized eco-system of textile-based electronic devices as communication, luminescent, energy harvesting and energy storage working on demand as micro-power source. In particular, the hot theme of energy storage is posing the development of new energy storage devices as a fundamental key also in the field of Textronic. Recently, great advances have been made in micro-fabrication of energy storage devices such as capacitors and batteries. However, the state of art is still unripe and further improvements about materials, technologies and strategies are needed. The thesis work manuscript was structured in five chapters. The first chapter introduces the main concepts of wearable electronics based on textiles, giving born to the new concept of “Textronic” (textile + electronics). The second chapter provides an overview of the state of art of energy storage for Textronic applications. The following chapters are experimental and describing the different approaches and materials that was investigated in order to obtain energy storage micro-devices able to be integrated in textiles. In terms of electrode design and configuration, two macro-areas were investigated as the development of (a) 1D wire-shaped and fibrous electrodes and (b) 2D planar microdevices. A fibrous shaped microcapacitor was proposed, based on a new material combination of PEDOT:PSS loaded in wet-spinned Kevlar nanofibers (KNF). The easy approach here proposed allowed fast production of fibrous conductive, mechanically robust, flexible electrodes with good electrochemical capacitance. However, a common lack in devices, material and approaches found in literature is the incompatibility of fibrous shaped (mainly made of carbon nanostructures) with conventional textile machining techniques. Moreover, coating techniques commonly employed for loading active materials on these 1D electrodes usually allow only few cm-long devices because they involve complex and long-lasting procedures. We then proposed an innovative route to produce meter-long thread electrodes to be employed in Zn/Ag battery chemistry. A custom-made setup allowed the continuous electrodeposition of Zn, Ni and Ag on commercially available conductive Ag-plated nylon thread. The as obtained Zn@Ag and Ni@Ag thread electrodes were successfully integrated in textile substrates by embroidery technique. Coupling with an in-situ crosslinked alkaline gel-polymer electrolyte, the embroidered Zn@Ag/Ni@Ag textile microbattery showed satisfactory energy storage performances and their feasibility in textronic application was demonstrated. Finally, inkjet printing of Ti3C2Tx MXene was investigated as suitable technique to obtain textile-based microcapacitors. Other then Ti3C2Tx MXene aqueous ink formulation, a new inkjet-printable UV-curable electrolyte precursor was proposed to obtain all inkjet-printed microcapacitors on textile. The optimized microdevices fabricated showed that the developed strategies and materials are feasible for energy storage and micro-power source applications in Textronic.
Molti esperti accordano sul fatto che il futuro dell’elettronica indossabile siano gli “smart fabrics” e l’elettronica indossabile verrà direttamente integrata nei nostri indumenti come micro-dispositivi e fibre piuttosto che gadget esterni. La transizione dalla classica elettronica indossabile verso il nuovo concept di “textile-based electronics” sta gettando le fondamenta di un nuovo settore tecnologico che è stato recentemente rinominato “Textronic”. Se da una parte sensori “textile-based” per il monitoraggio della salute hanno attirato una notevole attenzione per la loro potenzialità di portare l’assitenza sanitaria ad un nuovo livello assecondando il nuovo paradigma dell’approccio diagnostico predittivo, questi micro-dispositivi richiedono necessariamente lo sviluppo di un nuovo eco-sistema di microelettronica “textile-based” come ad esempio dispositivi di comunicazione, luminescenti, di recupero dell’energia ed accumulo e rilascio della stessa. Il tema sempre più centrale dell’accumulo di energia sta ponendo un ruolo chiave lo sviluppo di dispositivi per l’energy storage anche nel campo della Textronic. Il lavoro di tesi è stato strutturato in cinque capitoli. Il primo capitolo introduce i concetti principali dell’elettronica indossabile applicata ai tessuti, definendo il nuovo concetto di Textronic. Il secondo capitolo fornisce una panoramica sullo stato dell’arte dell’accumulo di energia applicato alla Textronic. I capitoli successivi sono sperimentali e descrivono le differenti strategie e materiali investigati allo scopo di sviluppare nuovi micro-dispositivi per l’energy storage in grado di essere integrati in tessuti. In termini di design e configurazione degli elettrodi, due macro-aree sono state considerate: lo sviluppo di (a) elettrodi 1D “fiber-shaped” e (b) elettrodi planari 2D. In particolare, è stato proposto un nuovo micro-condensatore “fiber-shaped” basato sulla combinazione di PEDOT:PSS caricato in fili di nanofibre di Kevlar (KNF) ottenuti via wet-spinning. La strategia proposta consente la facile produzione di elettrodi fibrosi conduttivi, meccanicamente robusti, flessibili e con una buona capacità. Tuttavia, una lacuna comune a molti dispositivi, materiali e metodi proposti in letteratura è l’incompatibilità degli elettrodi fibrosi 1D con le tecniche manifatturiere convenzionali di lavorazione e produzione dei tessuti. Inoltre, le metodologie di coating comunemente adottate per caricare di materiali attivi gli elettrodi 1D solitamente consentono il trattamento di elettrodi di lunghezza limitata (pochi cm) perché implicano procedure lunghe e/o complesse. Cercando di superare questa limitazione, l’elettrodeposizione è stata adottata per realizzare elettrodi lunghi fino decine di metri adatti all’impiego in batterie Zn/Ag. Un setup sviluppato ad-hoc ha consentito l’elettrodeposizione in continuo di Ag, Zn e Ni direttamente su fibre commerciali conduttive di nylon rivestito di argento. Gli elettrodi così ottenuti, Zn@Ag e Ni@Ag, sono stati integrati in tessuti utilizzando una macchina da ricamo automatizzata. Insieme ad un elettrolita alcalino semisolido, la batteria ricamata Zn@Ag/Ni@Ag ha dimostrato prestazioni adatte all’utilizzo nell’ambito della Textronic. Infine, la stampa inkjet di Ti3C2Tx MXenes è stata investigate come tecnica adatta per produrre “textile-based” micro-condensatori. In particolare, un nuovo elettrolita stampabile e reticolabile-UV è stato formulato. In generale, i micro-dispositivi proposti hanno mostrato che le strategie e materiali sviluppati sono adatti per il funzionamento come accumulatori di energia e micro-generatori per applicazioni nell’ambito della Textronic.
Fabrication of energy storage microdevices and their application on textiles
Gibertini, Eugenio
2021/2022
Abstract
Many experts agree that the future of wearables is smart fabrics and wearable electronics will be directly embedded in our clothes in the form of microdevices, yarns and fibers rather than external gadgets. The next transition from the classical flexible but rigid wearable electronics to the new textile-based one, is laying the foundations of a new technological field that was recently termed as “Textronic”. If one hand embedded textile-based sensors for human health monitoring gained tremendous attention because of their potentiality to bring healthcare to a next level accomplishing the new paradigm of predictive diagnostic approach, all of this microdevice necessarily require the development of a new highly miniaturized eco-system of textile-based electronic devices as communication, luminescent, energy harvesting and energy storage working on demand as micro-power source. In particular, the hot theme of energy storage is posing the development of new energy storage devices as a fundamental key also in the field of Textronic. Recently, great advances have been made in micro-fabrication of energy storage devices such as capacitors and batteries. However, the state of art is still unripe and further improvements about materials, technologies and strategies are needed. The thesis work manuscript was structured in five chapters. The first chapter introduces the main concepts of wearable electronics based on textiles, giving born to the new concept of “Textronic” (textile + electronics). The second chapter provides an overview of the state of art of energy storage for Textronic applications. The following chapters are experimental and describing the different approaches and materials that was investigated in order to obtain energy storage micro-devices able to be integrated in textiles. In terms of electrode design and configuration, two macro-areas were investigated as the development of (a) 1D wire-shaped and fibrous electrodes and (b) 2D planar microdevices. A fibrous shaped microcapacitor was proposed, based on a new material combination of PEDOT:PSS loaded in wet-spinned Kevlar nanofibers (KNF). The easy approach here proposed allowed fast production of fibrous conductive, mechanically robust, flexible electrodes with good electrochemical capacitance. However, a common lack in devices, material and approaches found in literature is the incompatibility of fibrous shaped (mainly made of carbon nanostructures) with conventional textile machining techniques. Moreover, coating techniques commonly employed for loading active materials on these 1D electrodes usually allow only few cm-long devices because they involve complex and long-lasting procedures. We then proposed an innovative route to produce meter-long thread electrodes to be employed in Zn/Ag battery chemistry. A custom-made setup allowed the continuous electrodeposition of Zn, Ni and Ag on commercially available conductive Ag-plated nylon thread. The as obtained Zn@Ag and Ni@Ag thread electrodes were successfully integrated in textile substrates by embroidery technique. Coupling with an in-situ crosslinked alkaline gel-polymer electrolyte, the embroidered Zn@Ag/Ni@Ag textile microbattery showed satisfactory energy storage performances and their feasibility in textronic application was demonstrated. Finally, inkjet printing of Ti3C2Tx MXene was investigated as suitable technique to obtain textile-based microcapacitors. Other then Ti3C2Tx MXene aqueous ink formulation, a new inkjet-printable UV-curable electrolyte precursor was proposed to obtain all inkjet-printed microcapacitors on textile. The optimized microdevices fabricated showed that the developed strategies and materials are feasible for energy storage and micro-power source applications in Textronic.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/188823