Thin film heaters, corrosion-resistance electrode, thin film inductors / Stretchable electronics are soft and light weight. Compared with conventional wafer-based electronics, which are rigid and planar, stretchable electronics can conform to curved surfaces and movable parts. The unique properties of stretchable electronics enable their integration with the human body, and open the door for ever more compelling applications, such as advanced surgical tools, wearable monitoring electronics, implantable prosthesis, and many others. However, the development of stretchable electronics is still at an early stage since their mechanical robustness and electrical performance are still far from satisfying. In this work, I have developed a method to fabricate thin film stretchable devices by solvent-assisted transfer of wrinkled thin films from rigid polystyrene (PS) substrates to elastomeric polydimethylsiloxane (PDMS) substrates. Using this approach, structured thin films containing multiple materials and hybrid structures could be lifted off simultaneously, facilitating the fabrication of stretchable thin film devices. With this approach, I have built corrosion-resistant stretchable electrodes, stretchable thin film heaters, and stretchable thin film inductors. These applications demonstrate the simplicity and effectiveness of this stretchable electronics fabrication strategy. Finally, I made the first step towards fabricating dye-sensitized solar cells (DSSCs) with room temperature processes, including the preparation of mesoporous TiO2 layers through mechanical compression and the integration of an interdigitated electrode that was fabricated solely by bench-top patterning, alignment, and sputtering deposition. These steps lay the foundation for the future development of stretchable DSSC. I anticipate that the fabricated stretchable thin films electronic components will contribute to the advancement of wearable and implantable electronics. / Thesis / Doctor of Philosophy (PhD) / Electronics that can be deformed and conform to the irregular surfaces are attractive because they can be better integrated with the human body. For example, they could improve disease diagnostics and therapeutic treatments by providing wearable continuous monitoring devices and more advanced surgical tools. In this work, I created wrinkled thin films that could be affixed onto an elastic substrate and stretched. The principle of operation of these wrinkled devices mimics the way that the wrinkled skin on our knuckles and elbows allows us to bend our fingers and elbows. This approach makes wrinkled thin films stretchable and could lead to robust electronic devices. I have showcased this approach building a corrosion-resistant stretchable electrode, thin films heaters that can closely conform to joints, and a spiral-shaped inductor that could be used to wirelessly transfer data or power wearable devices. I believe that this work will contribute to the development of electronics that can be worn or implanted in the human body.

To investigate the integration of a textile antenna into a woven substrate at the point of production. The antenna was to have the characteristics of a conventional fabric interms of the handle and drape.

This project explores design considerations and processes involved in the development of sports performance clothing specifically aimed at city cycling commuters. Research with a focus on smart clothing and electronic integration was used to form a technical framework in which the requirements of the end user were addressed. The result being the creation of a wearable electronic jacket containing a lighting system aimed at improving safety and comfort aspects affecting cycle commuters. The project methodology was essentially practice based with a strong experimental approach linked to the physical testing and refinement of electronic and clothing integration. Design aesthetics were equally important and are presented as a visual record linked to the use of computer related technologies which have influenced the design planning and processes of the project.

This project explores design considerations and processes involved in the development of sports performance clothing specifically aimed at city cycling commuters. Research with a focus on smart clothing and electronic integration was used to form a technical framework in which the requirements of the end user were addressed. The result being the creation of a wearable electronic jacket containing a lighting system aimed at improving safety and comfort aspects affecting cycle commuters. The project methodology was essentially practice based with a strong experimental approach linked to the physical testing and refinement of electronic and clothing integration. Design aesthetics were equally important and are presented as a visual record linked to the use of computer related technologies which have influenced the design planning and processes of the project.

The aim of this dissertation is to summarize my research on the development of multifunctional multimaterial fibers that are designed and produced for sensing and modulation applications in wearable and biomedical fields. Fiber-shaped devices have gained significant attention due to their potential in human-machine interface applications. These devices can be woven into fabrics to create smart textiles or used as implantable probes for various biomedical purposes. To meet the requirements of human-machine interface, these fiber devices need to be flexible, robust, scalable, and capable of integrating complex structures and multiple functionalities. The thermal drawing technique has emerged as a promising method for fabricating such fiber devices. It allows for the integration of multiple materials and intricate microstructures, thereby expanding the functionality and applications of the devices. However, the range of materials and structures that can be integrated into these fiber devices is still limited, posing a constraint on their potential applications. To address this limitation, the dissertation focuses on expanding the range of materials and structures that can be integrated into multimaterial fiber devices. This involves the development and application of stretchable electrical and optical deformation fiber sensors by incorporating composite thermoplastic elastomers through the thermal drawing process (Chapter 2). Additionally, the dissertation explores the use of the thermal drawing technique to create multifunctional ferromagnetic fiber robots capable of navigation, sensing, and modulation in minimally invasive surgery (Chapter 3). Furthermore, the integration of nano-optoelectrodes and micro robotic chips on the fiber tip using the combination of thermal drawing and lab-on-fiber techniques is investigated (Chapter 4). The dissertation concludes with an overview of the research findings and potential future directions in the field of multifunctional multimaterial fiber devices (Chapter 5). / Doctor of Philosophy / Human-machine interface (HMI) is the technology that enables communication and interaction between humans and machines or computer systems. It plays a vital role in various domains, including consumer electronics, robotics, healthcare, virtual reality, and industrial automation. Fiber-shaped devices have recently emerged as a promising technology for HMI applications due to their flexibility, lightweight nature, and versatile functionality. These devices can be seamlessly integrated into wearable forms, such as clothing or accessories, and even implanted in the body, opening up a wide range of possibilities for HMI. In the past decades, significant progress has been made in developing multifunctional multimaterial fiber devices using the thermal drawing process (TDP). TDP allows for the fabrication of fibers with complex geometries and microstructures by heating and drawing a preform consisting of different materials. However, the current range of materials and structures that can be integrated into these fiber devices is still limited, which hinders their potential applications. This dissertation aims to expand the capabilities of multimaterial fiber devices by exploring new materials and structures that can be incorporated using TDP. The research focuses on three main areas. First, the development and application of stretchable electrical and optical deformation fiber sensors by integrating composite thermoplastic elastomers are explored (Chapter 2). This enables the sensing of various deformations, enhancing the functionality of the fiber devices. Second, the dissertation investigates the creation of multifunctional ferromagnetic fiber robots capable of navigation, sensing, and modulation in minimally invasive surgery (Chapter 3). These robots offer new possibilities for precise and controlled interventions. Lastly, the integration of nano-optoelectrodes and micro robotic chips on the fiber tip using a combination of thermal drawing and lab-on-fiber techniques is explored (Chapter 4). This allows for advanced optical sensing and remote-control capabilities at the fiber tip. Overall, these three aspects of the project broaden the capabilities and functionalities of multifunctional multimaterial fibers, making them highly versatile and suitable for a wide range of applications in wearable technology and biomedicine. These advancements have the potential to revolutionize the field of human-machine interface (HMI) by enabling seamless and intuitive communication, control, and feedback between humans and machines.

No description available.

DYSPHONIA is a music and dance work, for violin soloist with a live chamber orchestra, including multiple laptops and a custom-built gesture detection system worn by a dancer. The piece was choreographed by Professor Charlotte Adams of the University of Iowa Dance Department and premiered at the Faculty Graduate Dance Concerts in February of 2015. This piece is inspired by ongoing research into computer programming, gesture and music-making, artificial intelligence (AI), and creative algorithms. While the actual algorithms I developed for use in this piece are far from sentient, it is my hope that this piece may bring about discussion and further interest in creative AI. In our initial discussions, choreographer Charlotte Adams and I discovered that we both have witnessed a large number of people buying into immersive technologies without questioning the total cost to their well being, without questioning whether the technology has a positive impact on their lives, and without an understanding regarding the complex changes being wrought in our society due to the mass adoption of such technologies. Thus we designed this piece around the technology itself, so that the union between the dancer and the prosthesis is brought about by the movement and action that takes place in the piece. The intent was to create a scene where the audience suddenly becomes aware that something new is happening, namely that the dancer’s glove has started to make noise and there is a new connection made between the music and the dance.

The next technological revolution, Industry 4.0, is envisioned as a digitally connected ecosystem where machines and gadgets are driven by artificial intelligence. By 2025, more than 75 billion devices are projected to serve this revolution. Many of which are to be integrated into the fabrics of everyday life in the form of smart wireless sensors. Still, two major challenges should be addressed to realize truly wireless and wearable sensors. First, the sensors should be flexible and stretchable, allowing for comfortable wearing. Second, the electronics should scavenge the energy it requires entirely from the environment, thus, eliminating the need for batteries, which are bulky, create ecological problems, etc. By addressing these two challenges, this dissertation paves the way for truly wearable sensors. The first part of the dissertation introduces a biocompatible magnetic skin with exceptional physical properties. It is highly-flexible, breathable, durable, and realizable in any desired shape and color. Attached to the skin of a user, the magnetic skin itself does not require any wiring, allowing to place the electronics and delicate components of the wireless sensor in a convenient nearby location to track the magnetic field produced by the magnetic skin. To demonstrate the performance of the magnetic skin, wearable systems are implemented as an assistive technology for severe quadriplegics, a touchless control solution for eliminating cross contaminations, and for monitoring blinking and eye movement for sleep laboratories. The second part of the dissertation is about wirelessly powering wireless sensors. In doing so, radio frequency (RF) rectifiers are a bottleneck, especially for ambient RF energy harvesting. Therefore, two RF rectifiers are introduced in standard CMOS technologies. The first architecture utilizes double-sided diodes to reduce the reverse leakage current, thus achieving a high dynamic range of 6.7 dB, -19.2 dBm sensitivity, and 86% efficiency. The second rectifier implements a dual-mode technique to lower the effective threshold voltage by 37%. Consequently, it achieves a 38% efficiency at −35 dBm input power and a 10.1 dB dynamic range while maintaining the same efficiency and sensitivity. Ultimately, combining these wireless powering techniques with the magnetic skin allows for truly wireless and wearable solutions.

No description available.

Abstract In this thesis flexible electronics composite materials were developed and utilized in pressure sensors. Additionally, stretchable materials based on piezoresistive structures were fabricated and their feasibility for printed electronics switches and stretchable strain sensors was investigated. In the first part of the thesis two types of composite materials were developed based on polyurethane foam with added carbon powder and on liquid crystal polymer with ceramic powder. The first developed composite was utilized in piezoresistive and capacitive hybrid sensors and the latter one for an additive manufactured piezoelectric sensor strip suitable for operation at elevated temperatures. The formable hybrid sensor achieved a maximum pressure sensitivity of 0.338 kPa-1 with response and recovery times less than 200 ms at pressures over 200 kPa and also showed a linear response. The sensor could be utilized, for example, in wearable electronics and robotics. The new type of piezoelectric material showed piezoelectric coefficients of d33 > 14 pC/N and g33 > 108 mVm/N at pressure below 10 kPa with a wide pressure sensing range up to 4.5 MPa. This was higher than that previously achieved for materials fabricated using traditional printing techniques. The piezoelectric sensor would be suitable for industrial process control at elevated temperatures. In the second part of the thesis the stretchable materials were utilized in a new type of piezoresistive structure to fabricate one of the first stretchable switches and a machine washable self-adherable strain sensor. The developed stretchable switch could be actuated with either stretching or vibration with a minimum movement of < 2 μm. The versatile strain sensor with a tunable resistance-strain characteristic achieved the currently highest reported gauge factor (>105) at > 70% stretching. The strain sensor could be utilized for sensing human body movements and physiological signals. / Tiivistelmä Väitöstyössä kehitettiin joustavan elektroniikan komposiittimateriaaleja, joita hyödynnettiin paineantureissa sekä käytettiin venytettäviä materiaaleja painettavan elektroniikan kytkimen ja venymäanturin valmistukseen. Työn ensimmäisessä osassa kehitettiin kahdenlaisia komposiittimateriaaleja, joista ensimmäinen pohjautui polyuretaanivaahtoihin, joihin sisällytettiin hiilijauhetta, sekä toinen nestekidepolymeeriin, johon lisättiin keraamijauhetta. Ensimmäistä kehitettyä komposiittia hyödynnettiin pietsoresistiivisessä ja -kapasitiivisessa hybridianturissa ja jälkimmäistä lisäaine valmistettavassa pietsosähköisessä anturinauhassa, joka soveltui kohotettuihin lämpötiloihin. Muovattavalla hybridianturilla saavutettiin herkkyyden maksimiarvoksi 0.338 kPa-1, alle 200 ms vaste- ja palautumisajat yli 200 kPa paineessa ja lineaarinen vaste. Anturia voitaisiin monipuolisesti hyödyntää mm. puettavassa elektroniikassa ja robotiikassa. Uudenlaisella pietsosähköisellä materiaalilla saavutettiin pietsosähköiset kertoimet (d33 > 14 pC/N ja g33 > 108 mVm/N < 10 kPa paineessa), jotka olivat korkeammat kuin perinteisin tulostusmenetelmin valmistetuilla materiaaleilla. Pietsosähköinen anturi soveltuisi mm. teolliseen prosessivalvontaan kohotetuissa lämpötiloissa. Toisessa osassa hyödynnettiin venytettäviä materiaaleja uudentyyppisissä pietsoresistiivisissä rakenteissa ensimmäisten venytettävän painettavan elektroniikan kytkimen sekä konepestävän itsekiinnityttävän venymäanturin valmistamiseksi. Tulokset on esitetty kahdessa julkaisussa, joista ensimmäinen keskittyi kytkimen valmistamiseen ja toimintaan sekä toinen venymäanturin toimintaan ihmiskehon liikkeen ja signaalien mittaamiseksi. Kehitettyä kytkintä voitiin aktuoida monipuolisesti esim. venytyksen tai värinän avulla alle 2 μm liikkeellä. Monipuolisella venymäanturilla saavutettiin säädettävä resistanssi-venymä suhde korkeimmalla tähän asti ilmoitettu herkkyydellä (>105) yli 70% venytyksellä. Venymäanturia voitiin hyödyntää ihmiskehon liikkeiden ja fysiologisten signaalien mittaamiseen.