Gijs Krijnen

Bio: Gijs Krijnen is an academic researcher from University of Twente. The author has contributed to research in topics: Capacitive sensing & Capacitance. The author has an hindex of 14, co-authored 73 publications receiving 874 citations. Previous affiliations of Gijs Krijnen include MESA+ Institute for Nanotechnology.

MEMS based hair flow-sensors as model systems for acoustic perception studies

Abstract: Arrays of MEMS fabricated flow sensors inspired by the acoustic flow-sensitive hairs found on the cerci of crickets, have been designed, fabricated and characterized. The hairs consist of up to 1 mm long SU-8 structures mounted on suspended membranes with normal translational and rotational degrees of freedom. Electrodes on the membrane and on the substrate form variable capacitors allowing for capacitive read-out. Capacitance versus voltage, frequency dependency and directional sensitivity measurements have been successfully carried out on fabricated sensor arrays, showing the viability of the concept. The sensors form a model-system allowing for investigations on sensory acoustics by their arrayed nature, their adaptivity via electrostatic interaction (frequency tuning and parametric amplifica- tion) and their susceptibility to noise (stochastic resonance)

Fabrication of microsieves with sub-micron pore size by laser interference lithography

Abstract: Laser interference lithography is a low-cost method for the exposure of large surfaces with regular patterns. Using this method, microsieves with a pore size of 65 nm and a pitch of 200 nm have been fabricated. The pores are formed by inverting a square array of photoresist posts with a chromium lift-off process and by subsequent reactive-ion etching using the chromium as an etch mask. The method has wider process latitude than direct formation of holes in the resist layer and the chromium mask allows for etching of pores with vertical sidewalls.

Embedded sensing: Integrating sensors in 3-D printed structures

Abstract: . Current additive manufacturing allows for the implementation of electrically interrogated 3-D printed sensors. In this contribution various technologies, sensing principles and applications are discussed. We will give both an overview of some of the sensors presented in literature as well as some of our own recent work on 3-D printed sensors. The 3-D printing methods discussed include fused deposition modelling (FDM), using multi-material printing and poly-jetting. Materials discussed are mainly thermoplastics and include thermoplastic polyurethane (TPU), both un-doped as well as doped with carbon black, polylactic acid (PLA) and conductive inks. The sensors discussed are based on biopotential sensing, capacitive sensing and resistive sensing with applications in surface electromyography (sEMG) and mechanical and tactile sensing. As these sensors are based on plastics they are in general flexible and therefore open new possibilities for sensing in soft structures, e.g. as used in soft robotics. At the same time they show many of the characteristics of plastics like hysteresis, drift and non-linearity. We will argue that 3-D printing of embedded sensors opens up exciting new possibilities but also that these sensors require us to rethink how to exploit non-ideal sensors.

Development of Soft sEMG Sensing Structures Using 3D-Printing Technologies.

Abstract: 3D printing of soft EMG sensing structures enables the creation of personalized sensing structures that can be potentially integrated in prosthetic, assistive and other devices. We developed and characterized flexible carbon-black doped TPU-based sEMG sensing structures. The structures are directly 3D-printed without the need for an additional post-processing step using a low-cost, consumer grade multi-material FDM printer. A comparison between the gold standard Ag/AgCl gel electrodes and the 3D-printed EMG electrodes with a comparable contact area shows that there is no significant difference in the EMG signals’ amplitude. The sensors are capable of distinguishing a variable level of muscle activity of the biceps brachii. Furthermore, as a proof of principle, sEMG data of a 3D-printed 8-electrode band are analyzed using a patten recognition algorithm to recognize hand gestures. This work shows that 3D-printed sEMG electrodes have great potential in practical applications.

Theory of cross-correlation analysis of PIV images : Image analysis as measuring technique in flows

Abstract: To improve the performance of particle image velocimetry in measuring instantaneous velocity fields, direct cross-correlation of image fields can be used in place of auto-correlation methods of interrogation of double- or multiple-exposure recordings. With improved speed of photographic recording and increased resolution of video array detectors, cross-correlation methods of interrogation of successive single-exposure frames can be used to measure the separation of pairs of particle images between successive frames. By knowing the extent of image shifting used in a multiple-exposure and by a priori knowledge of the mean flow-field, the cross-correlation of different sized interrogation spots with known separation can be optimized in terms of spatial resolution, detection rate, accuracy and reliability.

Introduction To Electrodynamics

Abstract: Thank you for downloading introduction to electrodynamics. Maybe you have knowledge that, people have look numerous times for their chosen books like this introduction to electrodynamics, but end up in infectious downloads. Rather than enjoying a good book with a cup of tea in the afternoon, instead they juggled with some malicious bugs inside their computer. introduction to electrodynamics is available in our book collection an online access to it is set as public so you can get it instantly. Our book servers spans in multiple countries, allowing you to get the most less latency time to download any of our books like this one. Merely said, the introduction to electrodynamics is universally compatible with any devices to read.

Multiprocess 3D printing for increasing component functionality.

Abstract: BACKGROUND Three-dimensional (3D) printing, known more formally as additive manufacturing, has become the focus of media and public attention in recent years as the decades-old technology has at last approached the performance necessary for direct production of end-use devices. The most popular forms of standard 3D printing include vat photopolymerization, powder bed fusion, material extrusion, sheet lamination, directed energy deposition, material jetting, and binder jetting, each creating parts layer by layer and offering different options in terms of cost, feature detail, and materials. Whereas traditional manufacturing technologies, such as casting, forging, machining, and injection molding, are well suited for mass production of identical commodity items, 3D printing allows for the creation of complex geometric shapes that can be mass-customized, because no die or mold is required and design concepts are translated into products through direct digital manufacturing. Furthermore, the additively layered approach enables the merging of multiple components into a single piece, which removes the requirement for subsequent assembly operations. Recently, the patents for the original 3D printing processes have begun to expire, which is resulting in a burgeoning number of low-cost desktop systems that provide increased accessibility to society at large. Industry has recognized the manufacturing advantages of these technologies and is investing in production systems to make complex components for jet engines, customized bodies for cars, and even pharmaceuticals. Although standard 3D printing technologies have advanced so that it is now possible to print in a wide range of materials including metals, ceramics, and polymers, the resulting structures are generally limited to a single material, or, at best, a limited number of compatible materials. ADVANCES For the technology to become more widely adopted in mainstream manufacturing, 3D printing must provide end-use products by fabricating more than just simple structures with sufficient mechanical strength to retain shape. Recently, research has resulted in the capability to use new materials with commercial 3D printers, and customized printers have been enhanced with complementary traditional manufacturing processes, an approach known as multiprocess or hybrid 3D printing. Collectively, these advancements are leading to fabrications that are not only geometrically complex, but functionally complex as well. By introducing the robotic placement of components, micromachining for intricate detail, embedding of wires, and dispensing of functional inks, complex structures can be constructed with additional electronic, electromagnetic, optical, thermodynamic, chemical, and electromechanical content. OUTLOOK Multiprocess 3D printing is a nascent area of research in which basic 3D printing is augmented to fabricate structures with multifunctionality. Progress will lead to local manufacturing with customized 3D spatial control of material, geometry, and placement of subcomponents. This next generation of printers will allow for the fabrication of arbitrarily shaped end-use devices, leading to direct and distributed manufacturing of products ranging from human organs to satellites. The ramifications are substantial, given that 3D printing will enable the fabrication of customer-specific products locally and on demand, improving personalization and reducing shipping costs and delays. Examples could include replacement components for grain-milling equipment in a remote village in the developing world, biomedical devices created specifically for a patient in a hospital before surgery, and satellite components printed in orbit, thus avoiding the delays and costs associated with launch operations. The automotive, aerospace, defense, pharmaceutical, biomedical, and consumer industries, among others, will benefit from the new design and manufacturing freedom made possible by multiprocess 3D printing.

Biomaterial systems for mechanosensing and actuation

Abstract: Living organisms use composite materials for various functions, such as mechanical support, protection, motility and the sensing of signals. Although the individual components of these materials may have poor mechanical qualities, they form composites of polymers and minerals with a remarkable variety of functional properties. Researchers are now using these natural systems as models for artificial mechanosensors and actuators, through studying both natural structures and their interactions with the environment. In addition to inspiring the design of new materials, analysis of natural structures on this basis can provide insight into evolutionary constraints on structure-function relationships in living organisms and the variety of structural solutions that emerged from these constraints.