Inkjet-printed SWCNT conductors and sensors on PDMS

Abstract. Inkjet printing of single-wall carbon nanotubes (SWCNT) on flexible polydimethylsiloxane (PDMS) substrates and their electrical properties were studied in this thesis. Wetting of the surface of the substrate with custom-made dimethylformamide-based conductive SWCNT ink was optimized by using argon-plasma surface treatment. Conductive micropatterns of SWCNTs were obtained. Mechanical bending and stretching experiments showed deformation dependent transport behaviour with a large pressure sensitivity and a gauge factor of up to 1000. The printed micropatterns were found to be sufficiently sensitive to detect and resolve pressure fronts of heartbeats in a human radial artery. Due to the established manufacturing processes used: inkjet- and screen printing, the study can pave the way for the integration of piezoresistive sensors in flexible and stretchable devices to be used e.g. in medical garments, sportswear and their accessories.Mustesuihkutulostetut yksiseinämäiset hiilinanoputkijohteet ja -anturit polydimetyylisiloksaanilla. Tiivistelmä. Tässä työssä tutkittiin yksiseinämäisten hiilinanoputkien (SWCNT) mustesuihkutulostamista joustavalle polydimetyylisiloksaanista (PDMS) valmistetulle substraatille sekä niiden sähköisiä ominaisuuksia. Erikoisvalmisteisen dimetyyliformamidipohjaisen johtavan SWCNT-musteen substraatin pinnan kostutusta optimoitiin argon plasma pintakäsittelyllä. Tuloksena saatiin monipuolisia johtavia SWCNT-mikrokuvioita. Taivutettaessa ja venytettäessä kuviot osoittivat muodonmuutoksesta riippuvaa johtavuuden vaihtelua suurella paineherkkyydellä ja jopa yli tuhannen venymäkertoimella (Gauge Factor). Mikrokuviot olivat riittävän herkkiä myös havaitsemaan ja tulkitsemaan sydämen sykkeen aiheuttaman paineenvaihtelun ihmisen rannevaltimosta. Vakiintuneiden valmistusmenetelmien, mustesuihkutulostuksen ja silkkipainon käytön takia, tutkimus voi tasoittaa tietä kohti taipuvissa ja venyvissä laitteissa käytettävien pietsoresistiivisten antureiden integrointia esimerkiksi lääketieteellisiin ja urheilutekstiileihin ja -tarvikkeisiin

Bioplastics and Carbon-Based Sustainable Materials, Components, and Devices: Toward Green Electronics

The continuously growing number of short-life electronics equipment inherently results in a massive amount of problematic waste, which poses risks of environmental pollution, endangers human health, and causes socioeconomic problems. Hence, to mitigate these negative impacts, it is our common interest to substitute conventional materials (polymers and metals) used in electronics devices with their environmentally benign renewable counterparts, wherever possible, while considering the aspects of functionality, manufacturability, and cost. To support such an effort, in this study, we explore the use of biodegradable bioplastics, such as polylactic acid (PLA), its blends with polyhydroxybutyrate (PHB) and composites with pyrolyzed lignin (PL), and multiwalled carbon nanotubes (MWCNTs), in conjunction with processes typical in the fabrication of electronics components, including plasma treatment, dip coating, inkjet and screen printing, as well as hot mixing, extrusion, and molding. We show that after a short argon plasma treatment of the surface of hot-blown PLA-PHB blend films, percolating networks of single-walled carbon nanotubes (SWCNTs) having sheet resistance well below 1 kω/□ can be deposited by dip coating to make electrode plates of capacitive touch sensors. We also demonstrate that the bioplastic films, as flexible dielectric substrates, are suitable for depositing conductive micropatterns of SWCNTs and Ag (1 kω/□ and 1 ω/□, respectively) by means of inkjet and screen printing, with potential in printed circuit board applications. In addition, we exemplify compounded and molded composites of PLA with PL and MWCNTs as excellent candidates for electromagnetic interference shielding materials in the K-band radio frequencies (18.0-26.5 GHz) with shielding effectiveness of up to 40 and 46 dB, respectively.Business Finland (project 1212/31/2020, All green structural electronics), EU Horizon 2020 BBI JU (project 792261, NewPack), and EU Interreg Nord Lapin liitto (project 20201468, Flexible transparent conductive f ilms as electrodes) and Academy of Finland (project 316825, Nigella)

Passiivikomponentti- ja diodikirjaston luominen LTspicessa

Tässä työssä tutkitaan LTspicen 4.23l -version vakiokomponenttikirjaston diodeja ja passiivikomponentteja ja niiden mallinnusta ohjelmassa. Mallinnuksen analysoinnissa kiinnitetään huomiota erityisesti LTspicen mallinnuksen vahvuuksiin ja puutteisiin. Työssä käsitellään myös helpot tavat tuoda uusia kolmannen osapuolen malleja ohjelmaan. Diskreettien .model-mallien tuonti esitellään useilla eri tavoilla ja useampia komponentteja sisältäviä .subckt-määrittelyä käyttävien mallien tuominen ohjelmaan esitetään LTspicen automaattista symbolinluontia hyödyntäen. Lisäksi pohditaan ohjelman sopivuutta erilaisiin tarpeisiin. Aineistona käytetään enimmäkseen LTspicen sisäistä apusivua, Linear Technologyn apuvideoita ja artikkeita ja lisäksi kolmannen osapuolen lähteitä ja omaa tutkimustyötä.This work is a study of diodes and passive components of the default component library of LTspice 4.23l and their modeling techniques. Attention in the model analysis is paid particularly to the strengths and weaknesses of LTspice’s way to model such components. The work also shows easy methods to import third party component models to the program. The importing of discrete component models described with .model statement are shown in multiple ways and also importing of the models described with .subckt statement, which include multiple discrete components, is shown using LTspice’s automatic symbol generation. Additionally, the suitability of the program to different kinds of simulation needs is contemplated. The material used is mostly LTspice’s internal help topics, Linear Technology’s help videos and articles together with third party sources and own research work

Personnel‘s perceptions of occupational safety in rail transport work

Abstract In rail transport work, a wide variety of occupational accidents occur. This questionnaire study aims to investigate the occupational safety (OS) challenges and needs recognised by railway personnel (N = 9404). Altogether, 1087 people answered. Answers were categorised thematically, and differences in perceptions between personnel groups and between different business sectors inside the company were identified. Differences between the category distributions were analysed with chi-square tests. Participatory approaches to improve OS emerged from the answers, e.g., attitudes, discussing and training OS. Statistically significant differences e.g., in the above-mentioned themes were found between the groups. The results provide vital information for the company to direct OS actions to the right business sectors. This study shows how personnel can contribute important views and feedback to OS development processes in a new way. The results suggest that more focused OS actions are needed. Guidance for the allocation, prioritisation and scheduling are provided

Inkjet-Deposited Single-Wall Carbon Nanotube Micropatterns on Stretchable PDMS-Ag Substrate-Electrode Structures for Piezoresistive Strain Sensing

[Image: see text] Printed piezoresistive strain sensors based on stretchable roll-to-roll screen-printed silver electrodes on polydimethylsiloxane substrates and inkjet-deposited single-wall carbon nanotube micropatterns are demonstrated in this work. With the optimization of surface wetting and inkjet printing parameters, well-defined microscopic line patterns of the nanotubes with a sheet resistance of <100 Ω/□ could be deposited between stretchable Ag electrodes on the plasma-treated substrate. The developed stretchable devices are highly sensitive to tensile strain with a gauge factor of up to 400 and a pressure sensitivity of ∼0.09 Pa(–1), respond to bending down to a radius of 1.5 mm, and are suitable for mounting on the skin to monitor and resolve various movements of the human body such as cardiac cycle, breathing, and finger flexing. This study indicates that inkjet deposition of nanomaterials can complement well other printing technologies to produce flexible and stretchable devices in a versatile manner

Inkjet-Deposited Single-Wall Carbon Nanotube Micropatterns on Stretchable PDMS-Ag SubstrateElectrode Structures for Piezoresistive Strain Sensing

[Image: see text] Printed piezoresistive strain sensors based on stretchable roll-to-roll screen-printed silver electrodes on polydimethylsiloxane substrates and inkjet-deposited single-wall carbon nanotube micropatterns are demonstrated in this work. With the optimization of surface wetting and inkjet printing parameters, well-defined microscopic line patterns of the nanotubes with a sheet resistance of <100 Ω/□ could be deposited between stretchable Ag electrodes on the plasma-treated substrate. The developed stretchable devices are highly sensitive to tensile strain with a gauge factor of up to 400 and a pressure sensitivity of ∼0.09 Pa(–1), respond to bending down to a radius of 1.5 mm, and are suitable for mounting on the skin to monitor and resolve various movements of the human body such as cardiac cycle, breathing, and finger flexing. This study indicates that inkjet deposition of nanomaterials can complement well other printing technologies to produce flexible and stretchable devices in a versatile manner

Inkjet-deposited single-wall carbon nanotube micropatterns on stretchable PDMS-Ag substrate-electrode structures for Piezoresistive strain sensing

Abstract Printed piezoresistive strain sensors based on stretchable roll-to-roll screen-printed silver electrodes on polydimethylsiloxane substrates and inkjet-deposited single-wall carbon nanotube micropatterns are demonstrated in this work. With the optimization of surface wetting and inkjet printing parameters, well-defined microscopic line patterns of the nanotubes with a sheet resistance of <100 Ω/□ could be deposited between stretchable Ag electrodes on the plasma-treated substrate. The developed stretchable devices are highly sensitive to tensile strain with a gauge factor of up to 400 and a pressure sensitivity of ∼0.09 Pa–1, respond to bending down to a radius of 1.5 mm, and are suitable for mounting on the skin to monitor and resolve various movements of the human body such as cardiac cycle, breathing, and finger flexing. This study indicates that inkjet deposition of nanomaterials can complement well other printing technologies to produce flexible and stretchable devices in a versatile manner