Electrode Materials for Supercapacitors in Hybrid Electric Vehicles: Challenges and Current Progress

For hybrid electric vehicles, supercapacitors are an attractive technology which, when used in conjunction with the batteries as a hybrid system, could solve the shortcomings of the battery. Supercapacitors would allow hybrid electric vehicles to achieve high efficiency and better power control. Supercapacitors possess very good power density. Besides this, their charge-discharge cycling stability and comparatively reasonable cost make them an incredible energy-storing device. The manufacturing strategy and the major parts like electrodes, current collector, binder, separator, and electrolyte define the performance of a supercapacitor. Among these, electrode materials play an important role when it comes to the performance of supercapacitors. They resolve the charge storage in the device and thus decide the capacitance. Porous carbon, conductive polymers, metal hydroxide, and metal oxides, which are some of the usual materials used for the electrodes in the supercapacitors, have some limits when it comes to energy density and stability. Major research in supercapacitors has focused on the design of stable, highly efficient electrodes with low cost. In this review, the most recent electrode materials used in supercapacitors are discussed. The challenges, current progress, and future development of supercapacitors are discussed as well. This study clearly shows that the performance of supercapacitors has increased considerably over the years and this has made them a promising alternative in the energy sector.

E-Skin Development and Prototyping via Soft Tooling and Composites with Silicone Rubber and Carbon Nanotubes

The strategy of embedding conductive materials on polymeric matrices has produced functional and wearable artificial electronic skin prototypes capable of transduction signals, such as pressure, force, humidity, or temperature. However, these prototypes are expensive and cover small areas. This study proposes a more affordable manufacturing strategy for manufacturing conductive layers with 6 × 6 matrix micropatterns of RTV-2 silicone rubber and Single-Walled Carbon Nanotubes (SWCNT). A novel mold with two cavities and two different micropatterns was designed and tested as a proof-of-concept using Low-Force Stereolithography-based additive manufacturing (AM). The effect SWCNT concentrations (3 wt.%, 4 wt.%, and 5 wt.%) on the mechanical properties were characterized by quasi-static axial deformation tests, which allowed them to stretch up to ~160%. The elastomeric soft material’s hysteresis energy (Mullin’s effect) was fitted using the Ogden–Roxburgh model and the Nelder–Mead algorithm. The assessment showed that the resulting multilayer material exhibits high flexibility and high conductivity (surface resistivity ~7.97 × 104 Ω/sq) and that robust soft tooling can be used for other devices.

Rapid meniscus-guided printing of stable semi-solid-state liquid metal microgranular-particle for soft electronics

Liquid metal (LM) is being regarded as the most feasible material for soft electronics owing to its distinct combination of high conductivity comparable to that of metals and exceptional deformability derived from its liquid state. However, the applicability of LM is still limited due to the difficulty of achieving its mechanical stability and intrinsic conductivity. Furthermore, reliable and rapid patterning of stable LM directly on various soft substrates at high-resolution remains a formidable challenge. In this work, meniscus-guided printing of ink containing polyelectrolyte-attached LM microgranular-particle (PaLMP) in an aqueous solvent to generate semi-solid-state LM is presented. PaLMP printed in the evaporative regime is mechanically stable, intrinsically conductive, and patternable down to 50 µm on various substrates. Demonstrations of the ultrastretchable (~500% strain) electrical circuit, customized e-skin, and zero-waste ECG sensor validate the simplicity, versatility, and reliability of this manufacturing strategy, enabling broad utility in the development of advanced soft electronics.

Automated platform for consistent part realization with regenerative hybrid additive manufacturing workflow

Nowadays, the role of hybridization within the wider manufacturing ecosystem gains significant momentum with multiple commercial solutions already available on the market. Despite the very promising benefits of combining and selectively exploiting the advantages of additive and subtractive technologies on the same machine, hybrid additive manufacturing is far from reaching its full potential. One of the central limitations of existing hybrid process chains is the lack of a harmonized, structured and automated workflows to support an adaptive manufacturing strategy. This work is motivated by the need to bridge this gap and to capture the logic behind an adaptive hybrid process chain with the aim to support the achievement of enhanced product quality and improved operational efficiency in hybrid additive manufacturing. The paper discusses the implementation of a hybrid CAx platform and the underlying methodology aiming at the dynamic reduction of variabilities associated with the laser metal deposition process. The hybrid workflow identifies the most adapted sequence and planning of additive and subtractive operations while considering part inspection as an in-envelope functionality to quantify the geometrical and dimensional part deviations and to trigger the regenerative mechanism. The methodology is demonstrated on a hybrid machine by deploying laser ablation for the in situ removal of build deviations and an adapted deposition operation as part of a regenerative strategy leading to higher part confidence.

Systematic review of manufacturing strategy studies focusing on congruence aspect

PurposeThis study provides a systematic review of the literature within the manufacturing strategy (MS) domain focusing on the congruence aspect of different strategic functions to determine the state-of-the-art research progression and the trend of publications.Design/methodology/approachWe have adopted a five-stage review methodology consisting - 1) Article Identification; 2) Inclusion/Exclusion; 3) Review of the Articles; 4) Literature Analysis; 5) Future research directions. 121 articles focusing on congruence aspects and specific to the MS domain are identified and reviewed. Bibliometric analysis comprising keyword co-occurrence using a VOSviewer© software, and citation analysis is performed. Further, content analysis is carried out to categorize articles based on the type of research methodology, type of tool/method used, and aspects considered for congruence study.FindingsBased on the research gaps identified in the existing literature on the congruence aspect within the MS domain, this study offers future research directions. Majorly, the work found is an empirical survey. Literature scants to develop a framework that helps to quantify the congruence between two strategic functions.Research limitations/implicationsThis study facilitates researchers and practitioners to understand the congruence between different strategic aspects studied in the literature and the level of fit between them. Further, the identified research directions can encourage researchers and practitioners to conceive novel approaches to conduct future works on congruence theme.Originality/valueThe unicity of the current review lies in its theme, i.e. congruence aspect within MS. To the best of author's knowledge, no comparable study is observed to review the congruence aspect in any other domain.

The application of manufacturing audits to identify and analyze production strategies: study carried out in a small graphics company

Purpose - This study intends to identify, analyze and formulate manufacturing strategies for small companies. The application of management methodologies on manufacturing processes in small companies is not commonly adopted, since an immediate return is not generated, and when it is compared to the effort required to understand and apply it. Design/methodology/approach – An adaption to a manufacturing audit methodology was used, illustrated by using the application to a small printing company. Findings - The situation that occurs frequently in small and family-owned enterprises, where even making activities more professional is not considered relevant, and seen as a waste of time and money, can certainly be improved using manufacturing audits. However, with technological advances, even small companies need to develop and reflect on manufacturing strategies to remain in the market. Originality/value - This approach becomes efficient when it focuses and analyzes these strategies, which are usually unclear for small companies, identifying weaknesses and opportunities for improvement to leverage the competitiveness of these companies, by defining more effective strategies. In addition, the study contributes theoretically when it seeks to adjust a methodology that has already been consolidated in large corporations, and which needs to be adapted to the reality of the scenario presented. Keywords - Manufacturing strategy, auditing, printing industry.

A Two-Axis Piezoresistive Force Sensing Tool for Microgripping

Force sensing has always been an important necessity in making decisions for manipulation. It becomes more appealing in the micro-scale context, especially where the surface forces become predominant. In addition, the deformations happening at the very local level are often coupled, and therefore providing multi-axis force sensing capabilities to microgripper becomes an important necessity. The manufacturing of a multi-axis instrumented microgripper comprises several levels of complexity, especially when it comes to the single wafer fabrication of a sensing and actuation mechanism. To address these requirements, in this work, an instrumented two-axis force sensing tool is proposed, which can then be integrated with the appropriate actuators for microgripping. Indeed, based on the task, the gripper design and shape requirements may differ. To cover wide needs, a versatile manufacturing strategy comprising of the separate fabrication of the passive and sensing parts was especially investigated. At the microscale, signal processing brings additional challenges, especially when we are dealing with multi-axis sensing. Therefore, a proper device, with efficient and appropriate systems and signal processing integration, is highly important. To keep these requirements in consideration, a dedicated clean-room based micro-fabrication of the devices and corresponding electronics to effectively process the signals are presented in this work. The fabricated sensing part can be assembled with wide varieties of passive parts to have different sensing tools as well as grippers. This force sensing tool is based upon the piezoresistive principle, and is experimentally demonstrated with a sensing capability up to 9 mN along the two axes with a resolution of 20 μN. The experimental results validate the measurement error within 1%. This work explains the system design, its working principle, FEM analysis, its fabrication and assembly, followed by the experimental validation of its performance. Moreover, the use of the proposed sensing tool for an instrumented gripper was also discussed and demonstrated with a micrograsping and release task.