Microfluidic pH-sensing chips integrated with pneumatic fluid-control devices

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• 作者：Chen-Fu Lin ; Gwo-Bin Lee ; Chih-Hao Wang ; Huei-Huang Lee ; Wei-Yin Liao and Tse-Chuan Chou
• 关键词：Pneumatic fluid control ; pH sensor ; MEMS ; Micro-pump
• 刊名：Biosensors and Bioelectronics
• 出版年：2006
• 期刊代码：12_09565663
• 类别：ch
• 出版时间：15 February 2006
• 卷：21
• 期：8
• 页码：1468-1475
• 文件大小：354 K

摘要

This paper presents a microfluidic chip capable of performing precise continuous pH measurements in an automatic mode. The chip is fabricated using micro-electro-mechanical-systems (MEMS)-based techniques and incorporates polydimethylsiloxane (PDMS) microstructures, pH-sensing electrodes and pneumatic fluid-control devices. Through its enhanced microchannel design and use of pneumatic fluid-control devices, the microfluidic chip reduces the dead volume of the sample and increases the pumping rate. The maximum pumping rate of the developed micro-pump is 28 μL/min at an air pressure of 10 psi and a driving frequency of 10 Hz. The total sample volume consumed in each sensing operation is just 0.515 μL. As a result, the developed chip reduces the sample volume compared to conventional large-scale pH-sensing systems. The microfluidic chip employs the electrochemical sensing method to conduct precise pH level measurements. The sensing electrodes are fabricated by sputtering a layer of SiO₂–LiO₂–BaO–TiO₂–La₂O₃ (SLBTLO) onto platinum (Pt) electrodes and the pH value of the sample is evaluated by measuring the potential difference between the sensing electrodes and a reference electrode. Additionally, the integration of the microfluidic chip with a pneumatic fluid-control device facilitates automatic sample injection and a continuous sensing operation. The developed system provides a valuable tool with which to examine pH values in a wide range of biomedical and industrial applications.