The inmates are running the asylum

Metamaterials exhibit properties beyond those exhibited by conventional materials in conventional scenarios. These have been investigated both theoretically and experimentally at length. In many cases the underpinning physical understanding of metamaterials has greatly preceded our ability to manufacture constituent structures. However, the development of additive manufacturing techniques gives new possibilities for the fabrication of complex metamaterial structures, many of which cannot be realised through conventional fabrication methods. The literature to date contains contributions from a diverse group of researchers from the physical sciences, mathematics, and manufacturing technology in the creation of metamaterials for electromagnetic, acoustic and mechanical applications. It is proposed that additive manufacturing holds the key to realise the capabilities of this vibrant research community and permit the creation of new paradigms in fundamental structures but also exploitation through application. For this purpose, a literature review is presented which identifies key advances in metamaterials alongside additive manufacturing and proposes new opportunities for researchers to work together through intra/inter disciplinary research to realise structures which exhibit extraordinary behaviour(s). This review represents a comprehensive account of the state-of-the-art in the production of such metamaterials using additive manufacturing methods and highlights areas, which, based on trends observed in the literature, are worthy of further research and require a coordinated effort on behalf of the afore mentioned disciplines in order to advance the state-of-the-art.

Additive manufacturing of metamaterials: A review

Future of additive manufacturing: Overview of 4D and 3D printed smart and advanced materials and their applications

Digital fabrication courses that relied on physical makerspaces were severely disrupted by COVID-19. As universities shut down in Spring 2020, instructors developed new models for digital fabrication at a distance. Through interviews with faculty and students and examination of course materials, we recount the experiences of eight remote digital fabrication courses. We found that learning with hobbyist equipment and online social networks could emulate using industrial equipment in shared workshops. Furthermore, at-home digital fabrication offered unique learning opportunities including more iteration, machine tuning, and maintenance. These opportunities depended on new forms of labor and varied based on student living situations. Our findings have implications for remote and in-person digital fabrication instruction. They indicate how access to tools was important, but not as critical as providing opportunities for iteration; they show how remote fabrication exacerbated student inequities; and they suggest strategies for evaluating trade-offs in remote fabrication models with respect to learning objectives.

Remote Learners, Home Makers: How Digital Fabrication Was Taught Online During a Pandemic

Due to the wide diffusion of 3D printing technologies, geometric algorithms for Additive Manufacturing are being invented at an impressive speed. Each single step, in particular along the Process Planning pipeline, can now count on dozens of methods that prepare the 3D model for fabrication, while analysing and optimizing geometry and machine instructions for various objectives. This report provides a classification of this huge state of the art, and elicits the relation between each single algorithm and a list of desirable objectives during Process Planning. The objectives themselves are listed and discussed, along with possible needs for tradeoffs. Additive Manufacturing technologies are broadly categorized to explicitly relate classes of devices and supported features. Finally, this report offers an analysis of the state of the art while discussing open and challenging problems from both an academic and an industrial perspective.

From 3D Models to 3D Prints: an Overview of the Processing Pipeline

In this chapter, we are interested in fault-tolerance against transient faults, which occur during the execution of the application, see Sect. 3.3 for a discussion on transient faults and how they can be detected. Biochemical applications are executed based on the electrode actuation sequence, which is produced in the compilation task, see Chap. 5 When a transient error is detected during the execution, the original electrode actuation sequence has to be interrupted, and recovery actions have to be initiated to remedy the error. These recovery actions are a sequence of operations that have to be executed, and will have to be compiled also into an electrode actuation sequence. This chapter presents two approaches to compilation for error recovery, an offline approach, which can be used at design time, and an online approach, which is employed at runtime. The proposed techniques have been evaluated on several real-life and synthetic test cases and compared to related work.

Compilation for Error Recovery

This chapter presents the models we use for biochemical applications. We give an informal presentation of the syntax and semantics of the high-level protocol language and define the biochemical application model used in the book. The purpose of the high-level protocol language is to describe biochemical assays in a precise and unambiguous way to allow automatic extraction of the biochemical application. The biochemical application model represents the microfluidic operations of an assay and their interdependencies in terms of input and output relations. We first present a high-level protocol language called Aqua, which serves as the basis for the high-level language we consider in this book. Then, we present a sequencing graph model that captures the behavior of the biochemical protocol. Each node in the graph represents an operation and the edges represent fluid transport. The next chapter presents how the high-level language is compiled into the graph representation. The graph model is used as an input to several of the design tasks addressed in the book.

Biochemical Application Model

All the work presented in this book so far, has considered general-purpose regular biochip architectures, which use a rectangular electrode array. However, in practice, application-specific architectures are often preferred because of their reduced cost. In this chapter, we first motivate the use of application-specific architectures, and present the application-specific architecture synthesis problem. We tackle this problem in the context of permanent faults, aiming to obtain a fault-tolerant application specific architecture. Next, the chapter presents two solutions to the synthesis of fault-tolerant application-specific architectures. Starting from an initial architecture, our synthesis solutions use metaheuristics (Simulated Annealing and Tabu Search) that search through the solution space to find a minimum cost architecture that can satisfy the timing constraints of the application and tolerate a given number k of permanent faults.

Synthesis of Application-Specific Architectures

In this chapter, we address the problem of variability in the execution times of the operations, caused by the randomness in biochemical reactions. In previous chapters, we have proposed compilation techniques that derive the schedule of operations based on the assumption that each operation is characterized by a worst-case execution time (wcet). However, during the execution of the application, operations may finish earlier than their wcets, resulting in unexploited slack in the schedule. In this chapter, we present two strategies that can handle such variabilities: an online approach and an approach based on a quasi-static strategy. The online compilation strategy re-compiles the application at runtime when operations experience variability in their execution time, thus exploiting the slack to obtain shorter application completion times. The quasi-static compilation strategy determines offline a database of alternative implementations. During the execution of the application, several implementations are selected based on the current execution scenario with operation execution time variability. The experiments reflect the advantages and disadvantages of the proposed approaches. Both of our strategies have better results than prior work.

Compilation for Operation Execution Time Variability

In this chapter we propose a solution to the compilation of biochemical applications on a given biochip model. The assumptions are as follows: We consider that the reconfigurable operations are executed on rectangular modules, which group adjacent electrodes to form virtual devices that have a static placement throughout the execution of the operation. We assume that the biochip architectures consist of a rectangular array of electrodes, and that the biochemical applications are modeled using a graph model. Due to the computational complexity of the compilation problem, it is infeasible to obtain optimal solutions. Therefore, the solution proposed in this chapter is based on a metaheuristic optimization called Tabu Search, which is capable of solving complex compilation problems. The proposed solution is evaluated on several benchmarks and compared to existing compilation approaches.

Mirela Alistar

Papers

Compilation for Error Recovery

Biochemical Application Model

Synthesis of Application-Specific Architectures

Compilation for Operation Execution Time Variability

Module-Based Compilation