Collaborative Research: Scalable Manufacturing Enabled by Highly Tunable Multiphase Liquid Metal Pastes with Solid and Fluid Capsule Additives

液态金属如镓及其合金具有多种潜在应用，如电子器件、催化、能量收集和生物医学用途，但面临制造、可调性和成本方面的挑战，限制了它们的广泛应用。该研究项目旨在研究如何将小规模固体和/或流体填料纳入液态金属，即液态金属浆料，有可能扩大物理和化学性质的范围，并增加其对增材制造和其他技术的经济吸引力。为了克服与液态金属的高内聚能密度相关的挑战，该团队建议使用自然形成的纳米薄氧化镓壳作为润湿剂（或表面活性剂），用于封装不同相的异物。由此产生的液态金属浆料代表了一类具有未开发特性的新型材料，可以推进可穿戴电子产品，软机器人和电子产品的热管理。拟议研究的视觉和动手性质将使多平台社区外展，包括从事K-12旅游团与动手活动使用视频游戏控制器操作三维打印机在制造液态金属零件。这项研究旨在实现一种通用的方式来包裹气体，液体和固体内的液态金属，并了解在这样做的包裹天然氧化物的作用，其产生了原位形成的独特的“表面活性剂”。这些多相材料将通过在受控条件下混合（或鼓泡流体）形成，随后彻底表征以建立工艺-结构-性能关系。这项调查将阐明这种氧化物“表面活性剂”的工作机制，以创建泡沫和糊与困气穴和液体或固体物体，分别。氧化物的“包封”能力将使一类新的导电多相浆料具有高度可调的密度、流变性以及电导率和热导率。凭借新的基本见解，该项目还将致力于创建基于液态金属的材料，这些材料可以有效地三维打印到几乎任何组成和形状的基底上，用于两项特定研究。第一个目标是实现比纯液态金属高出10倍的成本效益和更轻的泡沫，但适用于可拉伸电子设备。第二项研究是创造一种糊状物，在应用时分泌少量的二次液体，从而改善下一代热界面材料的热机械接触。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

Liquid metals such as gallium and its alloys have a variety of prospective applications such as in electronic devices, catalysis, energy harvesting and biomedical use but face challenges with manufacturing, tunability and cost that limit them from widespread use. This research project seeks to investigate how incorporating small-scale solid and/or fluid fillers into the liquid metal, i.e. liquid-metal pastes, have the potential to extend the range of physical and chemical properties and increase their economic appeal for additive manufacturing and other technologies. To overcome the challenges associated with the high cohesive energy density of liquid metals, the team proposes to use naturally formed nanometer-thin gallium-oxide shells as a wetting agent (or surfactant) for encapsulating foreign materials of different phases. The resultant liquid-metal pastes represent a novel class of materials with unexplored properties that can advance wearable electronics, soft robotics, and thermal management of electronics. The visual and hands-on nature of the proposed research will enable multiplatform community outreach including engaging K-12 tour groups with a hands-on activity using a video-game controller to operate a three-dimensional printer in making liquid-metal parts.This research aims to realize a generalized way to encase gases, liquids, and solids inside liquid metals and to understand the role of the encasing native oxide in doing so, which creates a unique “surfactant” that forms in situ. These multiphase materials will be formed by mixing (or bubbling fluids) under controlled conditions and subsequently characterized thoroughly to establish process-structure-property relationships. The investigation will elucidate the mechanism by which this oxide “surfactant” works to create foams and pastes with trapped air pockets and liquids or solid objects, respectively. The oxide “enveloping” ability will enable a new class of conductive multiphase pastes with highly tunable density, rheology, as well as electrical and thermal conductivities. With the new fundamental insight, this project will also aim to create liquid-metal based materials that can be effectively three-dimensionally printed onto substrates with almost any composition and shape for two specific studies. The first one is to achieve a foam that is up to 10 times more cost-effective and lighter than pure liquid metals and yet fits for stretchable electronic devices. The second study is to create a paste that secretes small amounts of secondary liquid when applied and thereby improves thermo-mechanical contacts of next-generation thermal interface materials.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.