Construction of a MEMS-style Miniaturized Chemical Analysis System for Blood Analysis

针对血液分析系统设计了一种小型化分析系统(μ-TAS)，该系统由血气分析模块、血液电解质模块和参比电极模块叠加而成。虽然在单芯片上实现这样的系统很困难，但采用模块化结构可以很容易地实现具有多种功能的高度复杂的系统。一个独特之处在于，为了提高长期稳定性，研究了微型Ag/AgCl参比电极的结构和工作模式。通过用聚酰亚胺层保护银层并在使用该元件期间生长AgCl，获得了大约300h的寿命，这大约是传统结构的2000倍。利用该元件可以构建液结参比电极。因此，只有在该装置上才能独立测定K~(++)、Na~(++)、Cl~(-)以及pH。比较了用微型参比电极和宏观参比电极测得的离子选择电极的电位。实测值的偏差最多为几mV。除此之外，氧电极和二氧化碳电极也观察到了不同的响应。利用堆叠模块构建的系统可以对6名分析员进行在线风格的分析。除了开发传感模块外，还开发了一种用于液体输送的微泵。通过电化学方法产生或熄灭氢泡，并借助外加压力实现液体的输送。样品溶液实际上可以被引入到微流动通道中，并且可以改变泵送速率。

A miniaturized analysis system (μTAS) aiming for blood analysis system was realized by stacking modules for blood gases, blood electrolytes, and a reference electrode module. Although realization of such a system on a single chip is difficult, a highly sophisticated system with various functions can be realized easily using the modular structure.A peculiar point is that the structure and operational mode of the miniature Ag/AgCl reference electrode were studied to improve the long-term stability. By protecting the silver layer with a polyimide layer and growing AgCl during the use of the element, a lifetime of approximately 300 h was achieved, which was approximately 2000 times compared with that of a conventional structure. A liquid-junction reference electrode could be constructed using the element. As a result, determination of K^+, Na^+, and Cl^- as well as pH could be made independently only in this device. The potentials of the ion-selective electrodes measured with the miniature reference electrode were compared with those measured with a macroscopic reference electrode. The deviation of the measured values was at most several mV. In addition to this, distinct responses were observed with the oxygen electrode and the carbon dioxide electrode. An on-line style analysis for six analysts could be performed with a system constructed with the stacked modules.In addition to the development of the sensing modules, a micropump for liquid transport was developed. A hydrogen bubble was generated or extinguished electrochemically and liquid could be transported with the help of the exserted pressure. A sample solution could actually be introduced into a microflow channel and the pumping rate could be changed.