Digital fabrication of custom interactive objects with rich materials

As ubiquitous computing is becoming reality, people interact with an increasing number of computer interfaces embedded in physical objects. Today, interaction with those objects largely relies on integrated touchscreens. In contrast, humans are capable of rich interaction with physical objects and their materials through sensory feedback and dexterous manipulation skills. However, developing physical user interfaces that offer versatile interaction and leverage these capabilities is challenging. It requires novel technologies for prototyping interfaces with custom interactivity that support rich materials of everyday objects. Moreover, such technologies need to be accessible to empower a wide audience of researchers, makers, and users. This thesis investigates digital fabrication as a key technology to address these challenges. It contributes four novel design and fabrication approaches for interactive objects with rich materials. The contributions enable easy, accessible, and versatile design and fabrication of interactive objects with custom stretchability, input and output on complex geometries and diverse materials, tactile output on 3D-object geometries, and capabilities of changing their shape and material properties. Together, the contributions of this thesis advance the fields of digital fabrication, rapid prototyping, and ubiquitous computing towards the bigger goal of exploring interactive objects with rich materials as a new generation of physical interfaces.Computer werden zunehmend in Geräten integriert, mit welchen Menschen im Alltag interagieren. Heutzutage basiert diese Interaktion weitgehend auf Touchscreens. Im Kontrast dazu steht die reichhaltige Interaktion mit physischen Objekten und Materialien durch sensorisches Feedback und geschickte Manipulation. Interfaces zu entwerfen, die diese Fähigkeiten nutzen, ist allerdings problematisch. Hierfür sind Technologien zum Prototyping neuer Interfaces mit benutzerdefinierter Interaktivität und Kompatibilität mit vielfältigen Materialien erforderlich. Zudem sollten solche Technologien zugänglich sein, um ein breites Publikum zu erreichen. Diese Dissertation erforscht die digitale Fabrikation als Schlüsseltechnologie, um diese Probleme zu adressieren. Sie trägt vier neue Design- und Fabrikationsansätze für das Prototyping interaktiver Objekte mit reichhaltigen Materialien bei. Diese ermöglichen einfaches, zugängliches und vielseitiges Design und Fabrikation von interaktiven Objekten mit individueller Dehnbarkeit, Ein- und Ausgabe auf komplexen Geometrien und vielfältigen Materialien, taktiler Ausgabe auf 3D-Objektgeometrien und der Fähigkeit ihre Form und Materialeigenschaften zu ändern. Insgesamt trägt diese Dissertation zum Fortschritt der Bereiche der digitalen Fabrikation, des Rapid Prototyping und des Ubiquitous Computing in Richtung des größeren Ziels, der Exploration interaktiver Objekte mit reichhaltigen Materialien als eine neue Generation von physischen Interfaces, bei

Development of a Fabrication Technique for Soft Planar Inflatable Composites

Soft robotics is a rapidly growing field in robotics that combines aspects of biologically inspired characteristics to unorthodox methods capable of conforming and/or adapting to unknown tasks or environments that would otherwise be improbable or complex with conventional robotic technologies. The field of soft robotics has grown rapidly over the past decade with increasing popularity and relevance to real-world applications. However, the means of fabricating these soft, compliant and intricate robots still poses a fundamental challenge, due to the liberal use of soft materials that are difficult to manipulate in their original state such as elastomers and fabric. These material properties rely on informal design approaches and bespoke fabrication methods to build soft systems. As such, there are a limited variety of fabrication techniques used to develop soft robots which hinders the scalability of robots and the time to manufacture, thus limiting their development. This research focuses towards developing a novel fabrication method for constructing soft planar inflatable composites. The fundamental method is based on a sub-set of additive manufacturing known as composite layering. The approach is designed from a planar manner and takes layers of elastomeric materials, embedded strain-limiting and mask layers. These components are then built up through a layer-by-layer fabrication method with the use of a bespoke film applicator set-up. This enables the fabrication of millimetre-scale soft inflatable composites with complex integrated masks and/or strain-limiting layers. These inflatable composites can then be cut into a desired shape via laser cutting or ablation. A design approach was also developed to expand the functionality of these inflatable composites through modelling and simulation via finite element analysis. Proof of concept prototypes were designed and fabricated to enable pneumatic driven actuation in the form of bending soft actuators, adjustable stiffness sensor, and planar shape change. This technique highlights the feasibility of the fabrication method and the value of its use in creating multi-material composite soft actuators which are thin, compact, flexible, and stretchable and can be applicable towards real-world application

A Flexible Sensor and MIMU-Based Multisensor Wearable System for Human Motion Analysis

Motivation: Magnetic–inertial measurement units (MIMUs) and flexible sensors are widely used in the wearable measurement system for human motion monitoring, clinical gait detection, and robotics motion control. However, MIMUs demonstrate measurement error due to magnetic disturbance in the indoor environment, and flexible sensors usually have low performance on linearity and accuracy. Objective: This article is intended to eliminate the low-accuracy problem caused by magnetic disturbances and improve the measurement accuracy of MIMU–flexible-sensor-based wearable systems. Approach: 1) a three-stage real-time adaptive anti-disturbance data fusion (RT-ADF) algorithm is proposed, which contains an anti-disturbance filter based on a double Mahony filter along with a state observer, a signal holder for sensors’ data transmit synchronously, and a data fusion based on an adaptive Kalman filter; 2) the proposed algorithm is used and validated its performance on a designed MIMU–flexible sensor wearable system; and 3) ten groups of knee motions (flexion/extension), ten groups of hip motions (adduction/abduction), and ten groups of elbow motions (flexion/extension) have been done by seven subjects in the experiments. Main Results: The designed multisensor wearable system based on the presented data fusion algorithm demonstrates a high-accuracy performance under the magnetic disturbance environment, and the maximum root mean square error (RMSE) of the measured continuous 3-D motion angle of the knee, hip, and elbow cross all the experiments was 1.23°, 1.15°, and 3.67° for each axis.<br/

A Flexible Sensor and MIMU-Based Multisensor Wearable System for Human Motion Analysis

Motivation: Magnetic–inertial measurement units (MIMUs) and flexible sensors are widely used in the wearable measurement system for human motion monitoring, clinical gait detection, and robotics motion control. However, MIMUs demonstrate measurement error due to magnetic disturbance in the indoor environment, and flexible sensors usually have low performance on linearity and accuracy. Objective: This article is intended to eliminate the low-accuracy problem caused by magnetic disturbances and improve the measurement accuracy of MIMU–flexible-sensor-based wearable systems. Approach: 1) a three-stage real-time adaptive anti-disturbance data fusion (RT-ADF) algorithm is proposed, which contains an anti-disturbance filter based on a double Mahony filter along with a state observer, a signal holder for sensors’ data transmit synchronously, and a data fusion based on an adaptive Kalman filter; 2) the proposed algorithm is used and validated its performance on a designed MIMU–flexible sensor wearable system; and 3) ten groups of knee motions (flexion/extension), ten groups of hip motions (adduction/abduction), and ten groups of elbow motions (flexion/extension) have been done by seven subjects in the experiments. Main Results: The designed multisensor wearable system based on the presented data fusion algorithm demonstrates a high-accuracy performance under the magnetic disturbance environment, and the maximum root mean square error (RMSE) of the measured continuous 3-D motion angle of the knee, hip, and elbow cross all the experiments was 1.23°, 1.15°, and 3.67° for each axis.<br/

The 3rd International Conference on the Challenges, Opportunities, Innovations and Applications in Electronic Textiles

This reprint is a collection of papers from the E-Textiles 2021 Conference and represents the state-of-the-art from both academia and industry in the development of smart fabrics that incorporate electronic and sensing functionality. The reprint presents a wide range of applications of the technology including wearable textile devices for healthcare applications such as respiratory monitoring and functional electrical stimulation. Manufacturing approaches include printed smart materials, knitted e-textiles and flexible electronic circuit assembly within fabrics and garments. E-textile sustainability, a key future requirement for the technology, is also considered. Supplying power is a constant challenge for all wireless wearable technologies and the collection includes papers on triboelectric energy harvesting and textile-based water-activated batteries. Finally, the application of textiles antennas in both sensing and 5G wireless communications is demonstrated, where different antenna designs and their response to stimuli are presented

Wearable Sensors for Monitoring the Internal and External Workload of the Athlete

The convergence of semiconductor technology, physiology, and predictive health analytics from wearable devices has advanced its clinical and translational utility for sports. The detection and subsequent application of metrics pertinent to and indicative of the physical performance, physiological status, biochemical composition, and mental alertness of the athlete has been shown to reduce the risk of injuries and improve performance and has enabled the development of athlete-centered protocols and treatment plans by team physicians and trainers. Our discussions in this review include commercially available devices, as well as those described in scientific literature to provide an understanding of wearable sensors for sports medicine. The primary objective of this paper is to provide a comprehensive review of the applications of wearable technology for assessing the biomechanical and physiological parameters of the athlete. A secondary objective of this paper is to identify collaborative research opportunities among academic research groups, sports medicine health clinics, and sports team performance programs to further the utility of this technology to assist in the return-to-play for athletes across various sporting domains. A companion paper discusses the use of wearables to monitor the biochemical profile and mental acuity of the athlete

Pop-Up Stretchable Sensor Designs Using Multiphysics Modeliing

Stretchable electronic devices are critical for the future of wearable sensor technology, where existing rigid and non-flexible devices severely limit the applicability of them in many areas. Stretchable electronics extend flexible electronics one step further by introducing significant elastic deformation. Stretchable electronics can conform to curvy geometries like human skin which enables new applications such as fully wearable electronics whose properties can be tuned through mechanical deformation. Much of the effort in stretchable electronics has focused on investigation of the optimum fabrication method to make a trade-off between the manufacturing cost and acceptable performance. Here in this thesis a novel pop-up strain sensor design is introduced and tested.This technique is simple to use and can be applied to almost all available materials such as metals, dielectrics, semiconductors and different scales from centi-meter to nanoscale. Using this method three main electronic devices have been designed for different applications. The first category is pop-up antennas that are able to reconfigure their frequency response with respect to the mechanical deformation by out of plane displacement. The second category is pop-up frequency selective surface which similarly can change its frequency behaviour due to applied strain. This ability to accommodate the applied stress by three-dimensional (3D) deformation, making these devices ideal for strain sensing applications such as vapor sensing or on skin mountable sensors. Using the advantage of RFID technology in terms of wireless monitoring, the third category has been introduced which is a pop-up capacitor sensor integrating with an RFID chip to detect finger joint bending that can help those patients who are recovering after stroke. The proposed devices have been modelled using COMSOL Multiphysics and Extensive evaluations of the prototype system were conducted on purpose-built laboratory scale test rigs. Both results are in good correlation which makes them applicable for sensing purposes

Magnetosensitive e-skins for interactive electronics

The rapid progress of electronics and computer science in the last years has brought humans and machines closer than ever before. Current trends like the Internet of Things and artificial intelligence are closing the gap even further, by providing ubiquitous data processing and sensing. As this ongoing revolution advances, novel forms of human-machine interactions are required in an ever more connected world. A crucial component to enable these interactions is the field of flexible electronics, which aims to establish a seamless link between living and artificial entities using electronic skins (e-skins). E-skins combine the functionality of commercial electronics with the soft, stretchable and biocompatible characteristics of human skin or tissue. Until lately, the focus had been to replicate the standard functions associated with human skin, such as, temperature, pressure and chemical detection. Yet, recent developments have also introduced non-standard sensing capabilities like magnetic field detection to create the field of magnetosensitive e-skins. The addition of a supplementary information channel—an electronic sixth sense—has sparked a wide range of applications in the fields of cognitive psychology and human-machine interactions. In this thesis, we expand the concept of magnetosensitive e-skins to include the notion of directionality, which utilizes the full interaction potential of the magnetic field vector. Also, we introduce the use of flexible magnetoelectronics in virtual/augmented reality and human-computer interfaces. Three main results are attained in the course of this work: (i) we first demonstrate how magnetosensitive e-skins can be used as humanmachine interfaces driven by permanent magnet sources in the range of 5 mT. (ii) Building upon this milestone, we realize the first magnetosensitive e-skins which are driven by the earth’s magnetic field of 50 μT. (iii) We fabricate magnetosensitive e-skins which push the detection limit below 1 μT. The magnetosensitive e-skins in this work open exciting possibilities for sensory substitution experiments and sensory processing disorder therapies. Futhermore, for human-machine interactions, they provide a new interactive platform for touchless and gestural control in virtual and augmented reality scenarios beyond the limitations of optics-based systems.Der rasante Fortschritt der Elektronik und der Informatik in den letzten Jahren hat Mensch und Maschine nähergebracht als je zuvor. Aktuelle Trends wie das Internet der Dinge und künstliche Intelligenz schließen die Lücke noch weiter, indem sie eine allgegenwärtige Datenverarbeitung und -erfassung ermöglichen. Mit fortschreitender Revolution sind neue Formen der Mensch-Maschine-Interaktion in einer immer vernetzter werdenden Welt erforderlich. Eine entscheidende Komponente, um diese Interaktionen zu ermöglichen, ist das Gebiet der flexiblen Elektronik, das darauf abzielt, mithilfe elektronischer Häute (e-skins) eine nahtlose Verbindung zwischen lebenden und künstlichen Entitäten herzustellen. E-skins verbinden die Funktionalität kommerzieller Elektronik mit den weichen, dehnbaren und biokompatiblen Eigenschaften menschlicher Haut oder menschlichen Gewebes. Bis vor kurzem lag der Schwerpunkt auf der Nachbildung der mit der menschlichen Haut verbundenen Standardfunktionen wie Temperatur-, Druck- und Chemikalienerkennung. Jüngste Entwicklungen haben jedoch auch nicht standardmäßige Erfassungsfähigkeiten wie die Magnetfelderkennung eingeführt, um das Feld magnetoempfindlicher e-skins zu erzeugen. Die Hinzufügung eines zusätzlichen Informationskanals - eines elektronischen sechsten Sinns - hat eine breite Palette von Anwendungen auf den Gebieten der kognitiven Psychologie und der Mensch-Maschine-Interaktionen ausgelöst. In dieser Arbeit erweitern wir das Konzept der magnetoempfindlichen e-skins um den Begriff der Richtwirkung, bei dem das volle Wechselwirkungspotential des Magnetfeldvektors genutzt wird. Außerdem führen wir die Verwendung flexibler Magnetoelektronik in der virtuellen Realität / erweiterten Realität und in Mensch-Computer-Schnittstellen ein. Im Verlauf dieser Arbeit werden drei Hauptergebnisse erzielt: (i) Wir demonstrieren erstmals, wie magnetoempfindliche e-skins als Mensch-Maschine-Schnittstellen verwendet werden können, die von Permanentmagnetquellen im Bereich von 5 mT angetrieben werden. (ii) Aufbauend auf diesem Meilenstein realisieren wir die ersten magnetoempfindlichen e-skins, die vom Erdmagnetfeld von 50 μT angetrieben werden. (iii) Wir fertigen magnetoempfindliche e-skins, bei denen die Nachweisgrenze unter 1 μT liegt. Die magnetoempfindlichen e-skins in dieser Arbeit eröffnen aufregende Möglichkeiten für sensorische Substitutionsexperimente und Therapien bei sensorischen Verarbeitungsstörungen. Darüber hinaus bieten sie für die Mensch-Maschine-Interaktion eine neue interaktive Plattform für die berührungslose und gestische Steuerung in virtuellen und Augmented Reality-Szenarien, die über die Grenzen optikbasierter Systeme hinausgehen

Soft Active Materials for Actuation, Sensing, and Electronics

Future generations of robots, electronics, and assistive medical devices will include systems that are soft and elastically deformable, allowing them to adapt their morphology in unstructured environments. This will require soft active materials for actuation, circuitry, and sensing of deformation and contact pressure. The emerging field of soft robotics utilizes these soft active materials to mimic the inherent compliance of natural soft-bodied systems. As the elasticity of robot components increases, the challenges for functionality revert to basic questions of fabrication, materials, and design - whereas such aspects are far more developed for traditional rigid-bodied systems. This thesis will highlight preliminary materials and designs that address the need for soft actuators and sensors, as well as emerging fabrication techniques for manufacturing stretchable circuits and devices based on liquid-embedded elastomers.Engineering and Applied Science