A High Sensitivity Three-Dimensional-Shape Sensing Patch Prepared by Lithography and Inkjet Printing

Drop-on-demand (DoD) ink-jet printing is an efficient technology for depositing picoliter drops on various printing surfaces. DoD technology is compatible with various liquids and does not require contacting the printing media. DoD inkjet printing combines several advantages including high speed, quiet operation, and compatibility with a variety of printing surfaces. Moreover, DoD printing can make patterns without any additional lithographic process. Ink-jet printing can reduce the number of processing steps compared to conventional patterning processes, which results in a lower production cost. Therefore, DoD ink-jet technology is applied in many engineering and scientific applications (see Figure 1), such as the formation of the conductive tracks for printed circuit boards, color filters in flat panel displays and plasma displays, polymer light-emitting diode displays, organic transistors, and the construction of DNA microarrays [1]-[5].

Electrothermal purification is an effective method for achieving over 99.9 pct purity for graphite particles with minimal environmental impact. However, the lack of a suitable heat and electric resistivity model has hindered the scaling up of electrically heated fluidized bed (EHFB) reactors for graphite purification. In this study, three commercial natural graphite flake populations were tested in a bench-scale fluidized bed reactor at temperatures of up to 1000 °C. The experiments varied key parameters, including the graphite particle size, particle bed temperature, fluidization index, and electrode depth within the particle bed. Controlling the fluidized bed reactor at high temperatures requires an understanding of bed resistivity and how current flows throughout the EHFB system. The results show that fluidized bed resistivity decreases with temperature, with a diminished effect at higher temperatures. Smaller particles exhibit a higher resistance, likely due to a larger number of contact points required to pass current between the electrodes. In this study, a Finite Difference Method (FDM) model was developed using Visual Basic for Applications (VBA) in Excel®. Additionally, a Finite Element Method (FEM) model was created using COMSOL Multiphysics®. The FDM model assumes the current flows only radially, whereas the FEM model accounts for both radial and vertical current flow. The FDM model was validated against experimental data. Additionally, the FDM model was verified through a comparison with the FEM model. The FDM model showed good agreement with experimental resistance data and moderate agreement with power consumption, while the FEM model provided more accurate predictions by accounting for a detailed geometry and heat loss mechanisms. Achieving a uniform temperature distribution within the fluidized bed is influenced by the electrode’s contact area. Deeper immersion of the electrode enhances thermal uniformity and provides results that more closely match experimental observations.

Three-dimensional (3D) bioprinting techniques, developed over the past two decades, have the potential to fabricate living, patient-specific tissues and organs for use in regenerative medicine (Kesti et al. 2016). Inkjet-based bioprinting is one of the oldest yet promising technologies, which combines the solid freeform fabrication process and precise cell placement in 2D and 3D. Typically, inkjet printing takes digital data of an image or character from a computer and reproduces it on to a material or substrate using ink drops in a noncontact mode (Mohebi and Evans 2002). In addition to its wide application in automation office tool, it has also been widely used in microengineering for printing electronic materials (Sirringhaus et al. 2000). Inkjet printer deposits controlled volume of ink in a layer-by-layer fashion to predefined locations on successive layers to form a 3D construct (Xu et al. 2008). Drop-on-demand (DOD) printers, a commonly used inkjet printers, are used for biological and nonbiological applications. The idea of printing of biological substances was introduced by Klebe after using HP thermal DOD inkjet printer to deposit collagen and fibronectin in 1988 (Klebe 1988). Later, Thomas Boland customized the thermal inkjet printer for printing living cells in a viable state (Wilson and Boland 2003). After this, scientists have made great progress in patterning molecules such as DNA, depositing proteins (Eric et al. 2009, Ilkhanizadeh et al. 2007, Miller et al. 2006), and printing tissues and organs by inkjet printing (Okamoto et al. 2000). The current focus of inkjet bioprinting is fabrication of 3D structures with clinically significant heights to extend its effectiveness in the direction of clinical applications. In this chapter, we discuss about the principle of inkjet bioprinting technology, types of inkjet printers in use, materials used for printing, and the critical parameters involved in this technique. Then, challenges associated with techniques and the future perspectives are also discussed.

P097 Direct measurement of electric fields in human and monkeys during transcranial electric stimulation

In the search for efficient methodologies focused on up scaling production of low cost functional ceramic oxides, the implementation of Chemical Solution Deposition (CSD) in combination with drop on demand (DoD) inkjet printing technology is a challenge in materials science. When simple additive processing is implemented in continuous reel to reel systems with novel low-cost materials, the potential to further decrease the production costs of the whole manufacturing process is immense.Sets of parallel YBa2Cu3O7−x (YBCO) stripes, 250 nm thick and 150 μm wide, with critical current densities (Jc) of about 1.1 MA/cm2 at 77K and self field are obtained.On the other hand, different designs of magnetoresistive La0.7Sr0.3MnO3 (LSMO) devices with electrical resistances in the range of 10 KΩ including the contact pads, are drawn onto LaAlO3 (LAO) and SrTiO3 (STO) single crystals. We particularly investigate different strategies to increase pattern resolution and accuracy. Preliminary morphological and electrical characterizations of the device on cheaper amorphous, polycrystalline and textured substrates are presented.Therefore, this paper gives a summary of functional ceramic oxides patterning by combining CSD and inkjet printing methodologies onto different single crystal, polycrystalline and textured substrates. The present work demonstrates a powerful method of fabricating multifilamentary YBCO patterned coatings for low losses coated conductors (CC's) and LSMO magnetoresistive analog encoders for position sensing.

PurposeThe purpose of this paper is to deal with an identification of a novel ink-jet printing sensor fabrication technology for fabricating flexible carbon heaters of macro and micro sizes, carbon interdigitated (IDT) electrodes and silver IDT electrodes. The technology involved in the proposed ink-jet printing method and materials used for the formulation of homemade nano-conductive inks (digital inks) are discussed in detail. The ink-jet printed flexible carbon heaters of different sizes (macro and micro) and carbon IDT electrodes and flexible silver IDT electrodes can be used as the flexible sensing layers in electrochemical gas sensors for sensitive and selective gas sensing applications. The characterization of ink-jet printed carbon heaters on Kapton substrate and its results are discussed. Similarly, the results of formulation of silver nano-conductive ink and printing of silver IDT electrodes on Kapton and its characterization are reported here for the first time.Design/methodology/approachFlexible carbon heaters of different sizes (macro and micro), carbon micro-IDT electrodes and silver IDT electrodes patterns were developed using AutoCAD 2D and printed on the Kapton (polyimide sheet) flexible substrate using the home-made nano-conductive inks with the help of EpsonT60 commercial piezo-head-based drop-on demand technology printer with standard printing options.FindingsThe proposed novel method is able to print heater patterns and IDT electrode patterns of approximately 12 µm and approximately 1 µm thickness, respectively, on flexible substrate using the home-made nano-conductive inks of carbon and silver by using a commercial low-cost printer. The home-made nano-conductive inks can be re-used for multiple prints up to six months shelf life. The resistance of the carbon heater was measured as 88 O under normal atmospheric condition. The novel flexible carbon heater was tested for its functionality and found to be satisfactory. The resistance of the silver IDT flexible electrodes was measured as 9.5 O which is better than the earlier works carried out in this paper.Research limitations/implicationsThe main challenge is associated with cleaning of printing ink ejection system in the existing commercial printers. The customization of the existing printer in the near future can minimize the printing challenges.Practical implicationsThe novel ink-jet printing technology proposed in this work is cost-effective, capable of achieving bulk production of flexible sensor elements, and consumes the least device fabrication time and high material yielding. The printing can be done with commercial piezo-head-based ink-jet printers with custom-prepared nano-conductive inks. There is a huge market potential for this paper.Originality/valueBoth the carbon heaters and silver IDT electrodes were printed on Kapton flexible substrate by using the commercial printer for the first time. The paper is promising the revolution in flexible low-cost sensor fabrication for mass production, and it is an alternate for thin film and thick sensor fabrication methods. The future of sensor fabrication technology will be the ink-jet printing method. In this paper, the research developments of flexible carbon heaters and flexible silver IDT electrodes for the time are reported. The characterization of carbon heaters and silver IDT electrodes were carried out and confirmed that the results are favourable for gas sensor applications.

Modelling the behaviour of Pneumatic Artificial Muscle (PAM) has proven difficult due to its highly complicated structure, nonlinear nature of rubbery material, and air compressibility. To overcome these limitations, a FEM (Finite Element Method) model using Abaqus and CATIA is derived for the quantitative analysis on the impact of different factors on the pulling force of PAM. In the Abaqus a two parameter Mooney–Rivlin model is utilized to consider the hyper-elastic nature of flexible material. Then both Abaqus and CATIA are used in the parametric design of a 3-Dimensional model of PAM. Furthermore, the FEM model is employed to predict the static force exerted by PAM and the results show that the model is promising. The FEM model produces closer results to the test data for the typical PAM. Nonlinear behaviour of PAM is found to be obvious with an increase in both the contraction and the air pressure, different from the linear curves obtained by the fundamental geometrical model. Nonlinear changes in the PAM force are also observed in the numerical study on the effect of structural factors including initial braid angle, initial diameter, initial wall thickness, and flexible material. Besides, these phenomena can be explained by a connection between mechanical and morphological behaviour of PAMs with the FEM model. Generally, this modelling approach is more accurate compared to the fundamental theoretical model and more cost competitive compared to the empirical methods.

The thermal conductivity of emulsion-polymerized styrene–butadiene rubber (ESBR) composites filled with carbon nanotubes (CNTs), zinc oxide (ZnO) and alumina (Al2O3) was predicted using the finite element method (FEM). Two-dimensional (2D) FEM models, which involved the effects of aspect ratio (AR), shape, orientation and thermal conductivity anisotropy (TCA) of the CNTs, and interfacial thermal resistance (ITR), were used to simulate the microstructure of CNT filled ESBR composites. Also, 2D and three-dimensional (3D) FEM models were developed to simulate the microstructure of Al2O3 or ZnO filled ESBR composites. An increase in the thermal conductivity with increasing Al2O3 or ZnO loadings was predicted by the FEM. The orientation angle (OA) of the CNTs and the ITR strongly affect the thermal conductivity as predicted by the FEM. The TCA of the CNTs also has a prominent effect on the thermal conductivity when CNTs have a relatively small OA. At a given filler loading, the thermal conductivity increased with the increasing intrinsic thermal conductivity of the filler over a certain range for a particular shape of filler. The thermal conductivities predicted by the FEM were compared with those predicted by Agari's models and the experimental results. The trends of the thermal conductivity predicted by the FEM agreed with the experimental data. The thermal conductivity of the ESBR composites predicted by 2D and 3D spherical particle filler (SPF) FEM models as a function of ZnO and Al2O3 loading showed that the 3D SPF FEM model agreed well with the experimental results at low loadings (not higher than 20 phr), while the 2D SPF FEM model agreed well with the experimental results at high loadings (higher than 80 phr). In addition to being used for the analysis of existing composites, the proposed FEM models are useful for the design and optimization of new composite materials, and are expected to provide a more insightful understanding into the thermal conductivity of polymeric composites.

Background: Accurate registration for surgical navigation of laparoscopic surgery is highly challenging due to vessel deformation. Here, we describe the design of a deformable model with improved matching accuracy by applying the finite element method (FEM).Material and methods: ANSYS software was used to simulate an FEM model of the vessel after pull-up based on laparoscopic gastrectomy requirements. The central line of the FEM model and the central line of the ground truth were drawn and compared. Based on the material and parameters determined from the animal experiment, a perigastric vessel FEM model of a gastric cancer patient was created, and its accuracy in a laparoscopic gastrectomy surgical scene was evaluated.Results: In the animal experiment, the FEM model created with Ogden foam material exhibited better results. The average distance between the two central lines was 6.5mm, and the average distance between their closest points was 3.8 mm. In the laparoscopic gastrectomy surgical scene, the FEM model and the true artery deformation demonstrated good coincidence.Conclusion: In this study, a deformable vessel model based on FEM was constructed using preoperative CT images to improve matching accuracy and to supply a reference for further research on deformation matching to facilitate laparoscopic gastrectomy navigation.

A three-dimensional finite element method (FEM) model simulating the electrochemical behaviour of Pt coplanar thin-film electrodes used for liquid cell transmission electron microscopy measurements was developed. The model included reaction kinetics and it was applied for the oxygen evolution reaction (OER). Kinetic parameters of OER in the liquid cell were experimentally acquired and applied to the FEM model. Comparison between the experimental and simulated polarization curves demonstrated the reliability of the FEM predictions. The simulations were used to produce maps of the potential and current density distributions of the working and counter electrodes as well as for calculating the distribution of the current density in the liquid electrolyte. Two distinctive electrode geometries were evaluated with the FEM model. It was predicted that non-symmetrical electrode designs can cause unexpected electrochemical behaviour with respect to the electrolyte current density between working and counter electrodes accompanied by the presence of hot spots. The findings suggest that FEM simulations could be key to designing well-performing electrochemical microcells for liquid phase electron microscopy experiments.

Slope stability in the Himalayas is a critical issue due to the region's unique geological and tectonic characteristics. The rocks of Himalayas are fragile and weak due to complex deformational structures causing the instability of slopes which are common, posing significant risks to infrastructure and communities. The central Nepal is characterized by similar problems and while constructing the engineering structures, challenges might be encountered. This study is aimed at modelling slope stability along the Malekhu-Dhadingbeshi road section of NH43 lying at the central Nepal lesser Himalaya using Kinematic analysis and Finite Element Method (FEM) modelling. The FEM modelling was conducted using two different computer programs. It was carried out at six different potential slopes with multifaceted geometry composed of slightly to moderately weathered quartzites and phyllites. The potential slope sections were identified using satellite imagery and field observations with key indicators including the condition of the slope toe, the presence of dislodged rocks and the formation of tension cracks. Their geometries were then created from the survey data obtained from topographic survey in the field. Input parameters for the modeling, such as cohesion and friction angle were calculated using the Hoek-Brown criterion while unit weight, elastic modulus and uniaxial compressive strength of rocks were determined from laboratory tests. The modelling was carried out under static condition provided there are no external influences from seismic activity or water forces. Out of six identified slopes sections, three of them were found to be critical during kinematic analysis, which were further modelled using FEM. Results from FEM revealed the non-significant total displacement at all of the three slope sections with higher critical Strength Reduction Factor (SRF) making the slopes stable. The findings also highlight the strength of the slopes under current conditions, providing valuable information for infrastructure planning in the region.

This chapter introduces the fundamental concepts necessary to understand polymers in inkjet formulation: molecular weight, their solution properties and their behaviour under flow. The formulation challenges of printing high molecular weight polymers arising from these flow behaviours are introduced along with the degradation reactions occurring in both drop on demand (DOD) and continuous inkjet (CIJ) systems for synthetic polymers and naturally occurring polymers showing tertiary structure.

A method utilizing variable depth increments during incremental forming was proposed and then optimized based on numerical simulation and intelligent algorithm. Initially, a finite element method (FEM) model was set up and then experimentally verified. And the relation between depth increment and the minimum thickness tmin as well as its location was analyzed through the FEM model. Afterwards, the variation of depth increments was defined. The designed part was divided into three areas according to the main deformation mechanism, with Di (i=1, 2) representing the two dividing locations. And three different values of depth increment, Δzi (i=1, 2, 3) were utilized for the three areas, respectively. Additionally, an orthogonal test was established to research the relation between the five process parameters (D and Δz) and tmin as well as its location. The result shows that Δz2 has the most significant influence on the thickness distribution for the corresponding area is the largest one. Finally, a single evaluating indicator, taking into account of both tmin and its location, was formatted with a linear weighted model. And the process parameters were optimized through a genetic algorithm integrated with an artificial neural network based on the evaluating index. The result shows that the proposed algorithm is satisfactory for the optimization of variable depth increment.

Infrared thermography has already been proven to be a significant method in non-destructive evaluation since it gives information with immediacy, rapidity, and low cost. However, the thorniest issue for the wider application of IRT is quantification. In this work, we proposed a specific depth quantifying technique by employing the Gated Recurrent Units (GRUs) in composite material samples via pulsed thermography (PT). Finite Element Method (FEM) modeling provides the economic examination of the response pulsed thermography. In this work, Carbon Fiber Reinforced Polymer (CFRP) specimens embedded with flat bottom holes are stimulated by a FEM modeling (COMSOL) with precisely controlled depth and geometrics of the defects. The GRU model automatically quantified the depth of defects presented in the stimulated CFRP material. The proposed method evaluated the accuracy and performance of synthetic CFRP data from FEM for defect depth predictions.

The aim of this work was to develop a parameterized analytical and FEM (Finite Element Method) model of a switched reluctance motor. The developed analytical model was used to assess the performance of these types of motors, and is determined to be a tool for comparing and evaluating switched reluctance motors of various designs. The aim of the work was also the systematization of knowledge related to the operation, structure and methods of determining the static electromagnetic torque generated by switched reluctance motors. The FEM model (ANSYS) was, also, made in order to verify physical phenomena occurring during operation of these motors. Four laboratory tests were executed as part of the work prototypes of switched reluctance motors built at Warsaw University of Technology. A parameterized analytical model was developed and implemented in MATLAB. The model operation tests were conducted and as a result, the characteristics describing the dependence of the electromagnetic torque as a function of the current and the position of the rotor were obtained. The model was validated by confronting the analytical calculations supported by FEM simulation results with the measurement results. The usefulness of the results obtained with the use of the procured models was assessed.