Lopes Pedro Alhais, Fernandes Daniel Félix, Silva André F, Marques Daniel Green, de Almeida Aníbal T, Majidi Carmel, Tavakoli Mahmoud
Institute of Systems and Robotics, Department of Electrical Engineering, University of Coimbra, Coimbra 3030-290, Portugal.
Integrated Soft Materials Lab, Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States.
ACS Appl Mater Interfaces. 2021 Mar 31;13(12):14552-14561. doi: 10.1021/acsami.0c22206. Epub 2021 Mar 10.
A bi-phasic ternary Ag-In-Ga ink that demonstrates high electrical conductivity, extreme stretchability, and low electromechanical gauge factor (GF) is introduced. Unlike popular liquid metal alloys such as eutectic gallium-indium (EGaIn), this ink is easily printable and nonsmearing and bonds strongly to a variety of substrates. Using this ink and a simple extrusion printer, the ability to perform direct writing of ultrathin, multi-layer circuits that are highly stretchable (max. strain >600%), have excellent conductivity (7.02 × 10 S m), and exhibit only a modest GF (0.9) related to the ratio of percent increase in trace resistance with mechanical strain is demonstrated. The ink is synthesized by mixing optimized quantities of EGaIn, Ag microflakes, and styrene-isoprene block copolymers, which functions as a hyperelastic binder. When compared to the same composite without EGaIn, the Ag-In-Ga ink shows over 1 order of magnitude larger conductivity, up to ∼27× lower GF, and ∼5× greater maximum stretchability. No significant change over the resistance of the ink was observed after 1000 strain cycles. Microscopic analysis shows that mixing EGaIn and Ag microflakes promotes the formation of AgIn microparticles, resulting in a cohesive bi-phasic ink. The ink can be sintered at room temperature, making it compatible with many heat-sensitive substrates. Additionally, utilizing a simple commercial extrusion based printer, the ability to perform stencil-free, digital printing of multi-layer stretchable circuits over various substrates, including medical wound-dressing adhesives, is demonstrated for the first time.
一种双相三元Ag-In-Ga油墨被引入，它具有高电导率、极高的拉伸性和低机电应变系数（GF）。与诸如共晶镓铟（EGaIn）等流行的液态金属合金不同，这种油墨易于印刷且不涂抹，并且能与多种基材牢固结合。使用这种油墨和一台简单的挤出式打印机，展示了直接书写超薄多层电路的能力，这些电路具有高度的拉伸性（最大应变>600%）、优异的导电性（7.02×10 S m），并且与机械应变下迹线电阻增加百分比的比率相关的GF仅为适度的0.9。该油墨是通过混合优化量的EGaIn、银微片和作为超弹性粘合剂的苯乙烯-异戊二烯嵌段共聚物合成的。与不含EGaIn的相同复合材料相比，Ag-In-Ga油墨的电导率高出1个数量级以上，GF降低约27倍，最大拉伸性提高约5倍。在1000次应变循环后，未观察到油墨电阻有显著变化。微观分析表明，混合EGaIn和银微片促进了AgIn微粒的形成，从而形成了一种粘性双相油墨。这种油墨可以在室温下烧结，使其与许多热敏基材兼容。此外，首次展示了利用一台基于简单商业挤出的打印机，在包括医用伤口敷料粘合剂在内的各种基材上进行无模板数字印刷多层可拉伸电路的能力。
