Development on Ion Selective Microfluidic Electrochemical Sensor Using Potentiometric Method

?????? ????????? ?????? ????????? ?????????, ??????????????? ???????????? ?????? ?????? ??????, ?????? ??????, ????????? ?????? ??????????????? ?????? ???????????? ????????????. ??? ??????????????? single-walled carbon nanotubes??? ????????? solid contact ??????????????? ????????? ???????????????, ?????? ?????? ????????? ????????? ????????? ??????-???????????? ????????? ???????????????. ??? ???????????? ????????? ????????? ???????????? ?????? Open circuit potential?????? ???????????????. ????????? ????????? ????????? ????????? ????????? ????????? ?????? ???????????? ????????? ????????? ???????????????. ????????? ????????? ????????? ????????? ?????????(??????)??? ????????? ???????????? ???????????? ?????? ??????????????? ?????????. ??? ????????? ?????? ?????? ????????? super-Nernstian ????????? ?????????, ??????????????? 4.80 ??M??? ???????????????. ??? ????????? ?????? ?????? ?????? ????????? ???????????? ?????????. ????????? ????????? ????????? ??????, ????????????, ??????, ??????, ?????????, ??? ????????? ?????? ?????? ???????????? ????????? ?????? ???????????? ?????????. ??? ???????????? ?????? ????????? ??? ????????? SWCNT ????????? ????????? ??????-???????????? ????????? ???????????? ???????????? ????????? ????????????. ???????????? ????????? ?????????????????? ??????-???????????? ????????? ?????? ?????? ????????? ??? ????????? ????????? ??? ?????? ????????? ?????? ????????? ??????. ???????????? ?????? ?????? ?????? ????????? ????????? ?????? ???????????? super-Nernstian ????????? ?????????. ??????????????? 9.25 ??M??? ???????????????. ??????-???????????? ???????????? ???????????? ????????? ????????? ???????????? ?????? ???????????????, ??????????????? ?????? ???????????????. ?????? ??? ????????? ????????? ?????? ??????????????? ?????? ????????????, ??????-???????????? ????????? ?????? ??????, ????????????, ?????? ?????? ?????? ???????????? ????????? ?????????. ????????? ????????? ??????-???????????? ????????? ?????? ????????? ?????? ?????? ??? ????????? ??????????????? ????????? ???????????? ????????? ????????? ???????????? ????????????.The qualitative and quantitative detection of specific ions in solution is important in clinical diagnosis, environmental monitoring, and quality control in the food industry. In this work, we fabricated a solid contact ion-selective electrode (SC-ISE) based on single-walled carbon nanotubes (SWCNTs) and both strip type of SC-ISE and paper-fluidic device were developed. An open circuit potential technique was employed to measure potentiometric response of these electrodes. The performance of strip type of SC-ISE was investigated in the bulk system and the potentiometric response was measured by immersing the electrode in the solution. There was a linear dependence and a good correlation between potentiometric response and logarithm of potassium ion activity (10-5 to 1 M). This electrode showed a super-Nernstian response (112.1 ?? 2.9 mV / decade aK+) in the linear range, and the limit of detection (LOD) was 4.80 ??M. It also showed a rapid response time and stability. The selectivity coefficients of this electrode revealed good selectivity against common interfering ions such as calcium, magnesium, sodium, lithium, ammonium, and silver ions. Then, we developed a paper-fluidic device with a modified wax-patterned paper using the SWCNT film and applied it to a fluidic system. In the fluidic system, the analyte solution was dropped onto the wax-patterned paper on a paper-fluidic device and flowed laterally through the paper channel. The device also showed a super-Nernstian response (107.2 ?? 3.5 mV / decade aK+) in the same range of potassium ion concentration, and LOD was 9.25 ??M. There were a slight decrease in device sensitivity compared to that in the bulk system and a small increase of LOD. Although it means that the efficiency of paper-fluidic device slightly decreased, the device has several advantages of low-cost, disposability and rapid detection. For these reasons, paper-fluidic device will be useful in many fields widely with micromolar detection of target ion and cost-effectivity.Maste