Yokohama National University, Faculty of Engineering
(Bio Microsystem lab)

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● Tissue engineering

Lab on a chip research


Electrochemical microsystem for monitoring of ammonia metabolism of hepatocyte

 The progress of microfluidic technology has produced successful devices in various fields. Like in many other applications, the capability for the evaluation of evaluating cellular functions with a minimum amount of cells and reagents will also be beneficial in fields including stem cell research, drug screening, and cell biology. To this end, an issue is on-chip cultivation, sampling, and monitoring of changes of physical and/or chemical parameters. To realize these functions, we used electrochemical principles. In this study, we fabricated a microsystem that can carry out necessary procedures for monitoring of ammonia metabolism of hepatocytes.


 The microsystem consisted of a glass substrate with valve electrodes and sensing electrodes, and a polydimethylsiloxane (PDMS) substrate with microflow channels and a culture chamber (Fig.1). Electrowetting-based valves controlled transport of extracted culture medium and an electrolyte solution of an air-gap Severinghaus-type ammonia sensor. The extracted culture was transported to the sensing area one by one with a predetermined interval and the ammonia concentration was measured using the sensor. The decrease in the ammonia concentration as a result of metabolism could clearly be followed on the chip (Fig.2). The amount of cells required in the system was less than one-hundredth of that in conventional analyses.

Fig. 1 Ammonia monitoring chip

Fig. 2 Monitoring of ammonia metabolism of hepatocytes. Hepatocytes were seeded at densities of 11 cells/mm2 (○), 115 cells/mm2 (□) in the microsystem, and 11 cells/mm2 using a commercial kit (●).
W. Satoh, S. Takahashi, F. Sassa, J. Fukuda, and H. Suzuki, On-chip culturing of hepatocytes and monitoring their ammonia metabolism, Lab on a Chip (IF=6.26), 9(1), pp.35-7 (2009)




● Vascular
● Liver
● Hair
● Pacnreas
● Bone
● Lab Chip/ MEMS
● Surface modification
● Microbe

Fukuda Lab, Faculty of Engineering, Yokohama National University