Form factor (design)

Abstract: With the development of the internet-of-things for applications such as wearables and packaging, a new class of electronics is emerging, characterized by the sheer number of forecast units and their short service-life. Projected to reach 27 billion units in 2021, connected devices are generating an exponentially increasing amount of electronic waste (e-waste). Fueled by the growing e-waste problem, the field of sustainable electronics is attracting significant interest. Today, standard energy-storage technologies such as lithium-ion or alkaline batteries still power most of smart devices. While they provide good performance, the nonrenewable and toxic materials require dedicated collection and recycling processes. Moreover, their standardized form factor and performance specifications limit the designs of smart devices. Here, exclusively disposable materials are used to fully print nontoxic supercapacitors maintaining a high capacitance of 25.6 F g-1 active material at an operating voltage up to 1.2 V. The presented combination of digital material assembly, stable high-performance operation, and nontoxicity has the potential to open new avenues within sustainable electronics and applications such as environmental sensing, e-textiles, and healthcare.

Abstract: If truly thin embedded and human worn flexible electronics are to become a commercial reality for wearable electronics, medical devices, and internet of things tags, effective energy storage technologies that safely and robustly match the mechanical flexibility of the overall system form factor are required. At the same time, the energy and transient power needs of functions such as wireless connectivity, information display, and high sample rate sensing must be supported. These capabilities have time-dependent power and current requirements often not captured in simple energy and capacity metrics. In this paper, a progression of energy storage approaches, challenges and learning experiences will be presented from the perspective of an energy storage technology developer. The essential requirements for energy storage for feature-driven applications in flexible electronics are addressed with the goal of finding the most compelling fit between products needs, consumer safety and the technology capabilities of different energy storage approaches. Micropower modules from supercapacitors to microbatteries and their limitations for flexible electronics will be discussed in terms of capacity, power and charge retention as the starting point. Following this discussion, limitations of lithium technologies in this flexible and thin ( $ 1 mm) application space are also outlined. This paper then presents a review of key requirements for energy storage for high functionality flexible electronics prototype systems and some approaches that have been explored to meet those needs. This leads to the conclusion that safe, low cost, flexible electronics energy storage requirements may be most appropriately met using intrinsically stable battery chemistry. Furthermore, such a materials approach allows for simpler lower cost processing and packaging, such as additive printing and roll to roll processing of thin and therefore more mechanically flexible cells. Examples and performance data from such a zinc polymer battery technology are given and compared to other thin and flexible battery approaches.

Abstract: The cooling of high power components in notebook computers is uniquely challenging due to space constraints that limit the size of the thermal solution. As a result, for some applications, a method of inserting a "negative" thermal resistance into the heat flow path may be required in order to achieve higher component powers. In this paper we describe a small-scale refrigeration system for the cooling of high power components in notebook form factors. The small-scale refrigeration system includes a compressor, cold plate, condenser, and throttling device. These components are designed for a vapor-compression cycle with iso-butane as the working fluid. All of these components are designed such that the entire system can be incorporated within a notebook form factor. In order to achieve the targeted performance, the cold plate and condenser contain microchannels to efficiently transfer heat to and from the refrigerant. Prototypes of each of the components were built and tested in order to assess their individual performance. A complete form factor loop was also built and tested in order to determine overall system feasibility and performance. The test results show that the targeted performance of the system (COP > 2.25) is achievable in this form factor at the moderate temperature rise expected in this application

Abstract: In recent years, important progress has been made in developing design strategies, materials, and associated assembly techniques that provide empowering approaches to electronics with unconventional formats, ones that allow useful but previously hard to realize attributes of function. Notable examples of the progress made include: light weight, large area, high performance electronics, optics, and photonics; electronic and optical systems with curvilinear shapes and capacities for accommodating demanding forms of mechanical flexure; new device form factors for use in sensing and imaging; the integration of high performance electronics in 3-D with demanding nanometer design rules; functional bioresponsive electronics; and advanced hybrid materials systems for lighting, energy storage, and photovoltaic energy conversion. In this report we highlight advances that are enabling such promising capabilities in technology—specifically, the fabrication of device elements using high performance inorganic electronic materials joined with printing and transfer methods to effect their integration within functional modules. We emphasize in this review considerations of the design strategies and assembly techniques that, when taken together, circumvent limitations imposed by approaches that integrate circuit elements within compact, rigid, and essentially planar form factor devices, and provide a transformational set of capabilities for high performance flexible/stretchable electronics.