Netsu Sokutei, 30 (1), p. 25, (2003)



Development of a Microcalorimeter for Detecting the Output Energy of nW

ナノカロリーメータへの基本的検討を行い,開発を試みた上で性能テストを行った。今回,試作したカロリーメータの代表的改良点は,(1)大気圧変動に伴う温度ノイズを除去するためサーモモジュールを改良,(2)ベースラインドリフトを軽減させるためサーモモジュールの感度調整回路を改良,(3)熱量計用恒温水の水温安定性の向上,(4)静電・電磁ノイズカップル対策,などである。得られた熱量計の性能は,長時間ベースラインドリフト,P-P 0.02 µV 4 K-1 24 h-1(0.18 µW)以下,ノイズレベル,P-P 0.016 µV(0.144 µW)であった。改良後の熱量計は,約1 µWの階段的な電気エネルギー供給に対し,熱量検出値に良好な直線性(R2=0.9999)を示した。また,本熱量計の高感度特性の適用例として,コイン型亜鉛空気1次電池の低出力負荷時の発生熱量測定を行い,大変良好な結果が得られた。
The basic examination has been made for the development of a calorimeter detecting a nano-watt output voltage and an efficiency of a newly constructed calorimeter has been tested. The representative improvements of the calorimeter are as follows; (1) improvement of the thermomodule for the exclusion of temperature noise incident to atmospheric pressure change, (2) improvement of a circuit regulating the sensibility of the thermomodule for the reduction of the base-line drift, (3) temperature stabilization of a water bath immersing the calorimeter, and (4) elimination for the electrostatic and electromagnetic coupling noise. The precision of the calorimeter was less than 0.02 µV 4 K-1 24 h-1(0.18 µW) for the base line drift in a long time and 0.016 µV (0.144 µW) for the noise-level of the base line. The linear relation of the thermal detection to the step-wise supply of the electric energy by about 1 µW has been found in the devised calorimeter. As an efficiency test of the calorimeter, calorimetric measurement of a Zn/O2 coin-type cell at low generating power has been carried out, resulting in good effect.