Duarte Junior Gerson F, Fracassi da Silva José Alberto, Mendonça Francisco Kelliton José, do Lago Claudimir Lucio, Carrilho Emanuel, Coltro Wendell K T
Instituto de Química, Universidade Federal de Goiás, Goiânia, Goiás, Brasil.
Instituto de Química, Universidade Estadual de Campinas, Campinas São Paulo, Brasil.
Electrophoresis. 2015 Aug;36(16):1935-40. doi: 10.1002/elps.201500033. Epub 2015 May 13.
This paper describes the use of ionic solutions as sensing electrodes for capacitively coupled contactless conductivity detection on electrophoresis microchips. Initially, two channels were engraved in a PMMA holder by using a CO2 laser system and sealed with a thin adhesive membrane. PDMS electrophoresis chips were fabricated by soft lithography and reversibly sealed against the polymer membrane. Different ionic solutions were investigated as metalless electrodes. The electrode channels were filled with KCl solutions prepared in conductivity values from approximately 10 to 40 S/m. The best analytical response was achieved using the KCl solution with 21.9 S/m conductivity (2 mol/L). Besides KCl, we also tested NaCl and LiCl solutions for actuating as detection electrodes. Taking into account the same electrolyte concentration (2 mol/L), the best response was recorded with KCl solution due to its higher ionic conductivity. The optimum operating frequency (400 kHz) and the best sensing electrode (2 mol/L KCl) were used to monitor electrophoretic separations of a mixture containing K(+) , Na(+) , and Li(+) . The use of liquid solutions as sensing electrodes for capacitively coupled contactless conductivity detection measurements has revealed great performance to monitor separations on chip-based devices, avoiding complicated fabrication schemes to include metal deposition and encapsulation of electrodes. The LOD values were estimated to be 28, 40, and 58 μmol/L for K(+) , Na(+) , and Li(+) , respectively, what is comparable to that of conventional metal electrodes. When compared to the use metal electrodes, the proposed approach offers advantages regarding the easiness of fabrication, simplicity, and lower cost per device.
本文描述了使用离子溶液作为传感电极，用于电泳微芯片上的电容耦合非接触式电导检测。最初，使用二氧化碳激光系统在聚甲基丙烯酸甲酯（PMMA）支架上刻蚀出两个通道，并用薄胶膜密封。通过软光刻技术制备了聚二甲基硅氧烷（PDMS）电泳芯片，并将其可逆地密封在聚合物膜上。研究了不同的离子溶液作为无金属电极。电极通道中填充了电导率值约为10至40 S/m的氯化钾（KCl）溶液。使用电导率为21.9 S/m（2 mol/L）的KCl溶液获得了最佳分析响应。除了KCl，我们还测试了氯化钠（NaCl）和氯化锂（LiCl）溶液作为检测电极。考虑到相同的电解质浓度（2 mol/L），由于KCl溶液具有较高的离子电导率，因此记录到了最佳响应。使用最佳工作频率（400 kHz）和最佳传感电极（2 mol/L KCl）来监测含有钾离子（K⁺）、钠离子（Na⁺）和锂离子（Li⁺）的混合物的电泳分离。使用液体溶液作为电容耦合非接触式电导检测测量的传感电极，在监测基于芯片的设备上的分离方面显示出了优异的性能，避免了包括金属沉积和电极封装在内的复杂制造方案。钾离子、钠离子和锂离子的检测限（LOD）值分别估计为28、40和58 μmol/L，与传统金属电极相当。与使用金属电极相比，所提出的方法在制造简便性、简单性和每台设备成本较低方面具有优势。
