School of Mechanical Engineering, Chonnam National University, Gwangju 500757, Republic of Korea.
Lab Chip. 2014 Jan 7;14(1):200-9. doi: 10.1039/c3lc50952d. Epub 2013 Nov 6.
Galinstan has the potential to replace mercury - one of the most popular liquid metals. However, the easy oxidation of Galinstan restricts wide applicability of the material. In this paper, we report an effective reduction method for the oxidized Galinstan using gas permeable PDMS (polydimethlysiloxane)-based microfluidic channel. The complete study is divided into two parts - reduction of Galinstan oxide and behavior of reduced Galinstan oxide in a microfluidic channel. The reduction of Galinstan oxide is discussed on the basis of static as well as dynamic angles. The contact angle analyses help to find the extent of reduction by wetting characteristics of the oxide, to optimize PDMS thickness and to select suitable hydrochloric acid (HCl) concentration. The highest advancing angle of 155° and receding angle of 136° is achieved with 200 μm thick PDMS film and 37 wt% (weight percent) HCl solution. The behavior of reduced Galinstan oxide is analyzed in PDMS-based coplanar microfluidic channels fabricated using a simple micromolding technique. Galinstan in the microfluidic channel is surrounded by another coplanar channel filled with HCl solution. Due to the excellent permeability of PDMS, HCl permeates through the PDMS wall between the two channels (interchannel PDMS wall) and achieves a continuous chemical reaction with oxidized Galinstan. A Lab VIEW controlled syringe pump is used for observing the behavior of HCl treated Galinstan in the microfluidic channel. Further optimization of the microfluidic device has been conducted to minimize the reoxidation of reduced Galinstan oxide in the microfluidic channel.
镓铟锡合金有可能取代汞——最受欢迎的液态金属之一。然而，镓铟锡合金很容易氧化，这限制了其广泛应用。在本文中，我们报告了一种使用透气 PDMS（聚二甲基硅氧烷）基微流控通道有效还原氧化镓铟合金的方法。整个研究分为两部分——氧化镓铟合金的还原和还原氧化镓铟合金在微流控通道中的行为。基于静态和动态角度讨论了氧化镓铟合金的还原。接触角分析有助于通过氧化物的润湿性特征来确定还原程度，优化 PDMS 厚度并选择合适的盐酸 (HCl) 浓度。使用 200μm 厚的 PDMS 膜和 37wt%（重量百分比）的 HCl 溶液可获得最大前进角 155°和后退角 136°。使用简单的微成型技术制造的基于 PDMS 的共面微流控通道分析了还原氧化镓铟合金的行为。微流控通道中的镓铟锡合金被另一个充满 HCl 溶液的共面通道包围。由于 PDMS 的优异透气性，HCl 通过两个通道之间的 PDMS 壁（通道间 PDMS 壁）渗透，并与氧化镓铟合金发生连续化学反应。使用 Lab VIEW 控制的注射器泵观察微流控通道中 HCl 处理后的镓铟锡合金的行为。进一步优化了微流控装置，以最小化微流控通道中还原氧化镓铟合金的再氧化。
