MEMSセンサによる少数細胞の代謝熱モニタリング Cell Metabolism Monitoring with MEMS Sensor
Cells and living tissue slightly but always generate metabolic heat as long as they are alive. Thus, biological activity can be measured through the observation of metabolic heat, which has been developed as “bio-calorimetry”. On the other hand, further improvements in thermal sensing ability can be expected with use of the MEMS (Micro Electro Mechanical System) technology. The purpose of this study is to develop the monitoring technique of the metabolic heat of cells in as small number as possible with the MEMS technology. If the monitoring technique of metabolism of a few cells or even a single cell is made available, it plays very important rolls in bio- and medical- engineering, pharmaceutical sciences, and so on. In this study, a bio-calorimeter with a MEMS thermopile sensor was made, and its performance and metabolism monitoring of Yeast were tested. The thermopile sensor consisted of 350 thin film thermocouples of Cr and Ni strips of 20 μm width on a 150 μm thick glass plate. The thermopile sensor composed a calorimetric cell as a bottom plate with thick aluminum frame. The calorimetric cell was placed in a triple thermostatic chamber which employs a proportional control with a Peltier device and PID control with heater. The calorimeter showed a sensitivity of 0.62 V/W under the condition of including culture solution, time constant of the calorimetric cell of 90 sec, and a noise equivalent power of 60 nW, which corresponds to metabolic heat of 3 × 10<sup>3</sup> cells of Yeast. In the growth experiments of Yeast, growth thermograms for 10<sup>5</sup>∼10<sup>7</sup> cells can be measured with reasonable generation times. It was demonstrated that the detectable number of Yeast cells of the MEMS calorimeter is much smaller than that for the traditional bio-calorimeter.
- Thermal science and engineering
Thermal science and engineering 14(4), 115-120, 2006-10-01