Functional Prototype Research Articles

Design and demonstration of a prototype thermally active student desk in a modern landmark for personalized cooling retrofits

This paper presents the design and evaluation of a prototype thermally active student desk (TASD) for personalized cooling retrofits using computational fluid dynamics (CFD) and field experiments. The study first developed an initial conceptual design for a TASD prototype made to esthetically match the desks in an architecture studio in a historic building that is frequently subject to comfort complaints. CFD simulations were used to validate the conceptual design and determine some component and system features. Four functional prototype TASDs for cooling were constructed and tested in the studio space with university students while the rest of the building was maintained at an extended temperature set point. CFD simulations predicted that the percent people of dissatisfied (PPD) would be ≤6% under all simulated scenarios. Surveys of 11 occupants who used the TASD revealed PPD of 9% (1/11), while PPD was 14% (17/120) among participants seated elsewhere in the building. The mean level of satisfaction (LOS) was similar among the two groups and thermal sensation vote (TSV) was slightly lower for the TASD users. This study demonstrates how a personalized conditioning system could be designed and integrated into the existing esthetics of buildings to provide cooling retrofits and potentially save energy.

DESIGN OF INSTRUMENTED INSOLE FOR GAIT DYNAMICS MONITORING

This article focuses on the design and implementation of a device aimed at monitoring gait dynamics. In clinical settings, gait dynamics are conventionally observed within specialized motion laboratories that rely on camera systems or pressure-sensitive floor mats. Unfortunately, these methods provide clinicians with only a temporally restricted perspective on a patient's health within the hospital environment. The objective of this study is to propose and develop a functional prototype of a measurement device that utilizes force-sensing resistors integrated into a sensorics insole placed within a shoe. By fusion of the 3D printing technology and force-sensing sensors, we developed a wearable prototype consisting of an instrumented insole and wireless data acquisition unit. This approach enables the capture of both static and dynamic parameters of gait, not only in clinical environments but also in non-hospital settings.

Dielectric flow- and tab-based battery thermal management system for EV high performance application

From the perspectives of security, durability, and proper operation, effective temperature control via thermal management systems (TMSs) on lithium-ion batteries is crucial for electric vehicle use. In this regard, a novel TMS based on dielectric flow and tab cooling was presented in this paper. A functional prototype of the system was developed and experimentally tested for performance analysis. A thermal model was built on computational fluid dynamics software, and a comparative analysis of the initial and an optimised geometry of the prototype was carried on after validation. Results demonstrate the adequate response of the system. Thermally speaking, temperature decrease was noticed during operation, and the internal and among-cells thermal gradient was preserved into the recommended span. Besides, the used dielectric fluid assisted with a low auxiliary consumption due to its particular viscosity. With the new geometry, the dielectric flow duct volume was reduced by 79.8%, and the system particularities were enhanced due to heat dissipation improvement: operating temperatures were even lower in every scenario examined. The temperature difference among cells was reduced by 15%. Thermal dispersion within the cells was still below the limit, despite being increased. Moreover, the necessary pumping energy consumption was below 0.004% of the exchanged battery module’s energy, demonstrating the TMS efficiency. Thus, the application potential of the dielectric tab cooling-based system for electric vehicles was highlighted.

Horngear and carrier design for braiding tailorable composite preforms

Braids can be found in structural composite parts used in the car and the aerospace industries. The architecture of the braid has a direct impact on its mechanical properties. However, traditional braiding machines are limited to a single braid architecture. Few braiding machines, so called “3D braiding machines”, have been developed to enable variable carrier’s paths. This allows fabrication of several braid architectures using the same machine. These machines use a switching mechanism, which complexifies the machine and the braiding process. A new type of braiding machine was introduced in Assi et al. [1], which uses a “chain and sprocket” mechanism, allowing variable carrier’s paths without any switching mechanism. Nevertheless, the original chain and sprocket braiding machine cannot be used for vertical braiding. When placed in the vertical position, the carrier jam between the horngears due to the force of gravity. This limitation does not allow braiding over a mandrel or coupling the braiding machine with a pultrusion line. This paper presents design guidelines for enabling vertical braiding for the chain and sprocket braiding machine. A new carrier design is proposed as well as a new horngear design. Additionally, the carrier is fitted with a guiding foot and a track is machined into the braider’s bedplate. A functional prototype has been developed to validate the design. The design complexity has been assessed and compared to existing braiding machines. The design proposed in this paper remains 30% less complex compared to other vertical braiding machines enabling variable carrier’s paths.

Optimization and Validation of an FTIR-based, All-in-one System for Viable MDR Bacteria Detection in Combat-related Wound Infection.

The U.S. Military members experiencing combat-related injuries have a higher chance of developing infections by multidrug-resistant (MDR) bacteria at admission to military hospitals. MDR wound infections result in higher amputation rates and greater risks for subsequent or chronic infections that require readmission or extended stay in the hospital. Currently, there is no FDA-clear, deployable early diagnostic system for suitable field use.We are reporting our efforts to improve a previously developed Rapid Label-free Pathogen Identification (RAPID) system to detect viable MDR bacteria in wound infections and perform antibiotic susceptibility testing (AST). Specifically, we added multiplex and automation capability and significantly simplified the sample preparation process. A functional prototype of the improved system was built, and its performance was validated using a variety of lab-prepared spiked samples and real-world samples. To access the baseline performance of the improved RAPID system in detecting bacteria presence, we selected 17 isolates, most of them from blood or wound infections, and prepared mono-strain spiked samples at 104 to 106 cfu/mL concentration. These samples were processed and analyzed by the RAPID system. To demonstrate the AST capability of the system, we selected 6 strains against 6 different antibiotics and compared the results from the system with the ones from the gold standard method.To validate the system's performance with real-world samples, we first investigated its performance on 3 swab samples from epicutaneous methicillin-resistant Staphylococcus aureus-exposed mouse model. The AST results from our system were compared with the ones from the gold standard method. All animal experiments were approved by the Johns Hopkins University Animal Care and Use Committee (Protocol No. MO21M378). Then, we obtained swab samples from 7 atopic dermatitis (AD) patients and compared our AST results with the ones from the gold standard method. The human subject protocol was approved by the Johns Hopkins Medicines Institutional Review Boards (Study No. CR00043438/IRB00307926) and by USAMRDC (Proposal Log Number/Study Number 20000251). High-quality data were obtained from the spiked samples of all 17 strains. A quantitative analysis model built using these data achieved 94% accuracy in predicting the species ID in 8 unknown samples. The AST results on the spiked samples had shown 100% matching with the gold standard method. Our system successfully detects the presence/absence of viable bacteria in all 3 mouse and 7 AD patient swab samples. Our system shows 100% and 85.7% (6 out of 7) accuracy when compared to the oxacillin susceptibility testing results for the mouse and the AD patient swabs, respectively. Our system has achieved excellent performance in detecting viable bacteria presence and in performing AST in a multiplex, automated, and easy-to-operate manner, on both lab-prepared and real samples. Our results have shown a path forward to a rapid (sample-to-answer time ≤3 hours), accurate, sensitive, species-specific, and portable system to detect the presence of MDR combat-related wound infections in the field environment. Our future efforts involve ruggedizing the RAPID system and evaluating performance under relevant environmental conditions.

EQS-Band Human Body Communication through frequency hopping and MCU-Based transmitter

Human Body Communication (HBC) is an emerging technology that uses the human body as a communication channel. It offers significant advantages over traditional RF techniques in terms of power consumption and security. In recent developments, Electro-quasistatic HBC (EQS-HBC) in the frequency band below 1 MHz has been employed to enable communication without signal radiation beyond the body, effectively turning the body into a wired communication medium. This paper delves into the application of the EQS band for HBC. Experimental results show the determinantal effect of intermittent noise that sporadically disrupts communications across the band of interest. To address this challenge, we introduce an innovative frequency-hopping transceiver system, which allows the transmitter to seamlessly adapt to different frequencies. In addition, we present a miniature transmitter design, incorporating a simplified micro-controller unit (MCU) to facilitate the implementation of HBC. Furthermore, to validate this proposed design, we present a fully functional prototype of an HBC system that effectively employs frequency hopping techniques for practical applications.

Constructing a game engine: A proposed game engine architecture course for undergraduate students

This paper presents a structured series of lessons for teaching undergraduate computer science or game development students how to construct a game engine using C++ and standard graphics APIs such as OpenGL or DirectX. Our proposed course content discusses rendering topics, game object management, scene management, and rigid body physics where learners are tasked to incorporate them into a fully functional prototype scene editor. By incorporating actual coding into the course, students can gain a better understanding of low-level engine features and also hone their programming skills. In addition to the learning content, we provide recommended assessment methods. We include discussions about our teaching experience in handling a game engine architecture course, titled GDENG03, which 36 students have passed. Our paper stands out from related works by providing a framework for interested educators on how to write a 3D game engine and how to teach the same in class. Based on our actual delivery of GDENG03, all 36 students achieved high scores of >80% out of 100 which demonstrates the effectiveness of our learning content. We received positive student feedback, such as a better appreciation of game engines, while suggestions for course improvement were raised, such as using simpler terminologies and better workload management. Based on student scores and feedback, we can attribute the success of our students’ learning to our inclusion of practical coding examples and discussions, highlighting their relevance to mainstream game engines. The learning materials and accompanying source code can be accessed in the following link: .

Design and Usability of an Open-Source, Low-Cost Flexible Laryngoscope for Resource-Limited Settings

Endoscopes are paramount to the practice of otolaryngology. To provide physicians in low-middle-income countries with adequate tools to treat otolaryngologic problems, it is necessary to create a low-cost sustainable option. To describe the design and usability of an open-source, low-cost flexible laryngoscope that addresses the lack of affordable and accessible methods for otolaryngologic visualization in resource-limited settings. This quality improvement study used a mixed-methods approach, including a technical description of device design as well as quantitative and qualitative survey evaluation of device usability. Engineering involved device design, sourcing or manufacturing individual components, fabricating a prototype, and iterative testing. Key assumptions and needs for the device were identified in collaboration with otolaryngologists in Zimbabwe, and designed and simulated by biomedical engineers in a US university laboratory. Board-certified otolaryngologists at a single US university hospital trialed a completed prototype on simulated airways between May 2023 and June 2023. Technical details on the design of the device are provided. Otolaryngologist gave feedback on device characteristics, maneuverability, and visualization using the System Usability Scale, a customized Likert-scale questionnaire (5-point scale), and semistructured interviews. A functional prototype meeting requirements was completed consisting of a distal-chip camera, spring bending tip, handle housing the control mechanism and electronics, and flexible polyether block amide-coated silicone sheath housing the camera and control wires; an external monitor provided real-time visualization and ability to store data. A total of 14 otolaryngologists participated in the device review. The mean (SD) System Usability Scale score was 88.93 (10.08), suggesting excellent usability. The device was rated highly for ease of set up, physical attributes, image quality, and functionality. This quality improvement study described the design of a novel open-source low-cost flexible laryngoscope that external review with otolaryngologists suggests was usable and feasible in various resource-limited environments. Future work is needed to translate the model into a clinical setting.

Catalyzing Clinically Driven Undergraduate Design Projects at the Nexus of Engineering, Medicine, and Business.

Design projects, particularly those related to assistive technology, offer unparalleled educational opportunities for undergraduate students to synthesize engineering knowledge with a clinically driven need to produce a product that can improve quality of life. Such projects are most effective when engineering, clinical, and business perspectives are considered throughout. However, the logistics of successfully implementing such interdisciplinary projects can be challenging. This paper presents an auto-ethnography of 12 undergraduate design team projects in assistive technology performed by 87 students from five majors (including engineering, business, and clinical students) over the course of 5 years. The overarching goal of our work was to establish an undergraduate integrated design experience at a university in the absence of a dedicated biomedical engineering major. The focus of this experience was to foster the creation of student-led prototypes to address real-world problems for people with disabilities while keeping commercialization potential at the forefront throughout. Student participation demonstrated a clear enthusiasm for completing biomedical engineering-themed projects. To encourage the implementation of similar approaches at universities where a biomedical engineering major does not exist, we identify common obstacles that can arise and present strategies for mitigating these challenges, as well as effective approaches for catalyzing cross-disciplinary collaborations. High impact practices include close involvement of end-users in the design process; cross-disciplinary team composition (e.g., engineering, business, and health sciences students); and choosing cross-disciplinary leads for project management. Teams experienced a high degree of success with all 12 teams producing functional prototypes. We conclude that at universities that do not offer a biomedical engineering major, health-focused integrated design experiences offer students important interdisciplinary perspectives, including a holistic approach to project implementation. Furthermore, for many students, these projects ultimately served as a gateway to subsequent careers and graduate study in biomedical engineering.

Impact Fracture Resistance of Fused Deposition Models from Polylactic Acid with Respect to Infill Density and Sample Thickness

Fused deposition modeling (FDM) is widely employed in prototyping due to its cost-effectiveness, speed, and ability to produce detailed and functional prototypes using a variety of materials. Simultaneously, consideration for the use of biodegradable polymers and a general reduction in their usage while enhancing the production of polymer-based products is at the forefront of sustainable practices and environmental consciousness. This study investigates the impact fracture resistance of FDM models fabricated from Polylactic Acid (PLA), examining the influence of infill density (50% and 100% infill) and sample thickness (2 mm, 3 mm, and 5 mm). Optical microscopy, FTIR spectroscopy, and SEM analysis of PLA filament and fractured FDM PLA surfaces in impacted samples were conducted to ascertain the influence of process parameters on impact damage and failure mechanisms. The results indicate that a 100% infill profile with a 2 mm thickness should be avoided due to unpredictable behavior under impact. Conversely, a 5 mm thickness demonstrates significantly higher durability in comparison to a 50% infill profile. Optimal impact strength is observed in samples with a 3 mm thickness, suggesting potential material savings with 50% infill without compromising mechanical properties. The findings contribute valuable insights for refining FDM parameters and advancing the understanding of material behaviors in sustainable manufacturing practices.

Gradual error detection technique for non-destructive assessment of density and tensile strength in fused filament fabrication processes

Fused filament fabrication (FFF) is a widely used additive manufacturing process for producing functional components and prototypes. The FFF process involves depositing melted material layer-by-layer to build up 3D physical parts. The quality of the final product depends on several factors, including the component density and tensile strength, which are typically determined through destructive testing methods. X-ray microtomography (XCT) can be used to investigate the pore sizes and distribution. These approaches are time-consuming, costly, and wasteful, making it unsuitable for high-volume manufacturing. In this paper, a new method for non-destructive determination of component density and estimation of the tensile strength in FFF processes is proposed. This method involves the use of gradual error detection by sensors and convolutional neural networks. To validate this approach, a series of experiments has been conducted. Component density and tensile strength of the printed specimens with varying extrusion factor were measured using traditional destructive testing methods and XCT. The cumulative error detection method was used to predict the same properties without destroying the specimens. The predicted values were then compared with the measured values, and it was observed that the method accurately predicted the component density and tensile strength of the tested parts. This approach has several advantages over traditional destructive testing methods. The method is faster, cheaper, and more environmentally friendly since it does not require the destruction of the product. Moreover, it facilitates the testing of each individual part instead of assuming the same properties for components from one series. Additionally, it can provide real-time feedback on the quality of the product during the manufacturing process, allowing for adjustments to be made as needed. The advancement of this approach points toward a future trend in non-destructive testing methodologies, potentially revolutionizing quality assurance processes not only for consumer goods but various industries such as electronics or automotive industry. Moreover, its broader applications extend beyond FFF to encompass other additive manufacturing techniques such as selective laser sintering (SLS), or electron beam melting (EBM). A comparison between the old destructive testing methods and this innovative non-destructive approach underscores the possible fundamental change toward more efficient and sustainable manufacturing practices. This approach has the potential to significantly reduce the time and cost associated with traditional destructive testing methods while ensuring the quality of FFF-manufactured products.

Dynamic visual servo control methods for continuous operation of a fruit harvesting robot working throughout an orchard

Fruit-picking robots are crucial for achieving efficient orchard harvesting. To genuinely meet the commercial production needs of farmers, the new generation of fruit-picking robots must be capable of demonstrating complete and continuous observation, movement, and picking behaviors throughout complex orchards, akin to real human employees. This poses systematic challenges, as many prior researches have focused solely on a part of the continuous operation of the entire orchard, such as fruit positioning, navigation, path planning, or grasping. These isolated basic functions are important but insufficient for fulfilling operational requirements on a macro scale and continuous situation. Developing an efficient control method for each basic module and constructing their internal coordination is vital for transitioning a harvesting robot from a functional prototype to a practical machine. In this context, this study tackles the visual servo control problem for efficient locomotion, picking, and their seamless integration. A set of vision algorithms for locomotion destination estimation, real-time self-positioning, and dynamic harvesting is proposed. Additionally, a solid coordination mechanism for continuous locomotion and picking behavior is established. Each method offers distinct advantages, such as improved accuracy, adaptability to varying conditions, and enhanced picking efficiency, enabling the robot to operate autonomously and continuously. Comprehensive field experiments validated the soundness of the methods. The primary contribution of this study lies in addressing the challenge of continuous operation in an entire orchard as a systematic problem and providing new insights into control methods for the future development of highly autonomous, practical, and user-oriented fruit harvesting systems.

Towards co-design of rehabilitation technologies: a collaborative approach to prioritize usability issues.

Early stakeholder engagement is critical to the successful development and translation of rehabilitation technologies, a pivotal step of which is usability testing with intended end-users. To this end, several methods employ end-user feedback to identify usability and implementation issues. However, the process of prioritizing identified issues seldom leverages the knowledge and expertise of the range of stakeholders who will ultimately affect the demand and supply of a device. This paper describes a novel method to prioritize end-user feedback using transdisciplinary stakeholder consultation and address it in subsequent product development. The proposed approach was demonstrated using a case study relating to the development of a novel technology for neural recovery after spinal cord injury. Feedback from five individuals with chronic spinal cord injury was collected during two-hour usability evaluation sessions with a fully functional high-fidelity system prototype. A think-aloud and semi-structured interview protocol was used with each participant to identify usability and acceptability issues relating to the system in a 3-phase approach. Phase 1 involved extracting usability issues from think-aloud and semi-structured interview data. Phase 2 involved rating the usability issues based on their significance, technical feasibility, and implementation priority by relevant internal and external stakeholders. Finally, Phase 3 involved aggregating the usability issues according to design and implementation elements to facilitate solution generation, and these solutions were then raised as action tasks for future design iterations. Sixty usability issues representing nine facets of usability were rated. Eighty percent of issues were rated to be of moderate to high significance, 83% were rated as being feasible to address, and 75% were rated as addressable using existing project resources. Fifty percent of the issues were rated to be a high priority for implementation. Evaluation of the grouped issues identified 21 tasks which were mapped to the product roadmap for integration into future design iterations. This paper presents a method for meaningful transdisciplinary stakeholder engagement in rehabilitation technology development that can extended to other projects. Alongside a worked example, we offer practical considerations for others seeking to co-develop rehabilitation technologies.

Unobtrusive Cognitive Assessment in Smart-Homes: Leveraging Visual Encoding and Synthetic Movement Traces Data Mining.

The ubiquity of sensors in smart-homes facilitates the support of independent living for older adults and enables cognitive assessment. Notably, there has been a growing interest in utilizing movement traces for identifying signs of cognitive impairment in recent years. In this study, we introduce an innovative approach to identify abnormal indoor movement patterns that may signal cognitive decline. This is achieved through the non-intrusive integration of smart-home sensors, including passive infrared sensors and sensors embedded in everyday objects. The methodology involves visualizing user locomotion traces and discerning interactions with objects on a floor plan representation of the smart-home, and employing different image descriptor features designed for image analysis tasks and synthetic minority oversampling techniques to enhance the methodology. This approach distinguishes itself by its flexibility in effortlessly incorporating additional features through sensor data. A comprehensive analysis, conducted with a substantial dataset obtained from a real smart-home, involving 99 seniors, including those with cognitive diseases, reveals the effectiveness of the proposed functional prototype of the system architecture. The results validate the system's efficacy in accurately discerning the cognitive status of seniors, achieving a macro-averaged F1-score of 72.22% for the two targeted categories: cognitively healthy and people with dementia. Furthermore, through experimental comparison, our system demonstrates superior performance compared with state-of-the-art methods.

Development of a Compact Incremental Forming Machine

Since the beginning of the 21st century, incremental sheet-metal-forming processes, such as single-point incremental forming (SPIF), have been the subject of extensive research. The SPIF process is highlighted as an efficient and cost-effective solution for producing complex parts with different materials and scales, surpassing conventional methods and being ideal for small series and customized products. Various machines can be used to implement SPIF, such as adapted milling machines, serial robots, and dedicated machines, each with its own advantages. However, although it requires a higher initial investment, a dedicated machine offers superior performance. The objective of this project was the creation of a compact and portable dedicated machine, which included the design of suitable kinematics, a mechanical project, and numerical control. The structural design led to the optimization of the dimensions of the robot arms. Direct and indirect kinematics were analyzed. Finally, the careful selection and adaptation of components were carried out, bearing in mind the support system of the forming punch, including the selection and sizing of motors, reducers, and linear actuators. A functional early prototype was successfully built and tested.

Analysis of Thermodynamic Events Taking Place during Vacuum Drying of Corn

Agricultural materials (LF products) can be considered biologically living organisms due to their structure and the composition of colloidal capillary-porous substances in them. They contain a large number of microscopic pores, microcapillaries and macrocapillaries, in which water is able to pass from the inner parts to the surface of the grain, and vice versa. Thus, it can be concluded that drying is an important and demanding aspect of agricultural production. To determine the optimal drying process for agricultural cereals from a nutritional, energy, economic and environmental point of view, it is necessary to address in detail the application of the technology of vacuum drying from a thermodynamic point of view. An analysis of the research results shows that drying temperature, harvest date and corn variety can significantly affect the properties of the main components of corn grain. This study investigates the individual technological parameters of the vacuum drying process for corn, such as the pressure used in the drying chamber, the grain drying temperature and the heating time, in order to achieve a maximum reduction in water content. The aim of the investigation is to determine the optimal parameters for the design of a functional prototype of a vacuum dryer. For this purpose, laboratory and semi-operational experiments using different types of organic materials are necessary. The structural design of the individual elements of the vacuum dryer is based on an analysis of laboratory and experimental tests, whose results are presented in this article.

Control of Autonomous Aerial Vehicles to Transport a Medical Supplies

Public health surveillance must guarantee the safety of people by limiting human mobility, in cases of isolation, through product deliveries, making it necessary to use drones to guarantee safety because they play a crucial role in several sectors. The literature review highlights the benefits of automation in-home delivery using drones, focusing on time efficiency and competitiveness in various sectors, and provides crucial design parameters to ensure its implementation in urban areas using different control techniques. A contribution was proposed to a solution that aims to realize the honeycomb design, which drones create during flight, controlled by a flight and delivery algorithm in a simulation environment applying an iterative methodology and continuous transport tests. medical burden. The results indicate a qualitative advance in the successful creation of simulated terrain, although the lack of numerical data on takeoffs and landings suggests the need for additional quantitative measurements. The current results support the efficiency of drones in route planning, precise management of medical cargo, and reduction of delivery time is numerical evidence that reinforces the robustness of the solution. In conclusion, this study developed a functional prototype to control drones with a flight planning algorithm and a swarm formation system for the transport of medical supplies in urban environments, although the need for future research to implement artificial intelligence technologies is noted. that improve transportation efficiency.

Underwater sound absorption characteristics of compliant acoustic coatings with adjustable stiffness

Abstract A type of compliant acoustic coating with adjustable stiffness is proposed by a combination of a multilayer adjustable stiffness element and a compliant skin. By adjusting its deformation, the stiffness of the acoustic coating switches between different steady levels, thus tuning its underwater sound absorption performance. Based on the series spring model and the effective medium theory, theoretical models are established for describing the adjustable stiffness of the multilayer element and the sound absorption characteristics of the acoustic coating cells. A conceptual coating model is designed, in which the multilayer adjustable stiffness element is composed of three layers of cells with different structural parameters, corresponding to three different stiffness. Theoretical analysis and numerical simulation are carried out to explore the adjustable stiffness characteristics and sound absorption characteristics of the concept model, with the numerical results of the adjustable stiffness and sound absorption characteristics validated experimentally. The influence of structural parameters is investigated, where the limb thickness t is found to present a dominant influence on the stiffness of the multilayer adjustable stiffness element and the increase in stiffness can improve sound absorption performance in the low and middle frequency bands. The conceptual model shows how the idealized conditions considered in this work could turn into functional prototypes of compliant acoustic coatings with adjustable stiffness.

A state-of-the-art review of 4D printing techniques, stimuli activated materials and future perspectives

In recent years, 4DP has gained significant interest in the field of AM, functional prototyping, soft robotics, biomaterials, pharmaceutical, and textiles. 4DP is an AM technique that integrates 3DP with stimuli-responsive materials. When exposed to various external stimuli, such as temperature, light, pH, magnetic field, electricity, and moisture; the structures formed by 4DP technique are space time dependent and can change their shape and/or properties over the period of time. Herein, this overview presents stimuli activated smart materials used in 4DP, 4DP techniques and practical applications of 4D printed smart structures. This overview also elucidates challenges and future perspectives in terms of, synthetization of different polymers, multi material printing, sustainability, pre-programming knowledge, and latent applications of 4D printed structures.

ASL champ!: a virtual reality game with deep-learning driven sign recognition

We developed an American Sign Language (ASL) learning platform in a Virtual Reality (VR) environment to facilitate immersive interaction and real-time feedback for ASL learners. We describe the first game to use an interactive teaching style in which users learn from a fluent signing avatar and the first implementation of ASL sign recognition using deep learning within the VR environment. Advanced motion-capture technology powers an expressive ASL teaching avatar within an immersive three-dimensional environment. The teacher demonstrates an ASL sign for an object, prompting the user to copy the sign. Upon the user’s signing, a third-party plugin executes the sign recognition process alongside a deep learning model. Depending on the accuracy of a user’s sign production, the avatar repeats the sign or introduces a new one. We gathered a 3D VR ASL dataset from fifteen diverse participants to power the sign recognition model. The proposed deep learning model’s training, validation, and test accuracy are 90.12%, 89.37%, and 86.66%, respectively. The functional prototype can teach sign language vocabulary and be successfully adapted as an interactive ASL learning platform in VR.