사진식각법을 이용한 CO2 센서 감지막의 제조

박이순; 김상태; 고광락

Journal of the Korean Industrial and Engineering Chemistry, Vol.9, No.1, 6-12, February, 1998

Export Citation

사진식각법을 이용한 CO2 센서 감지막의 제조

Fabrication of CO₂ Sensor Membrane by Photolithographic Method

박이순, 김상태, 고광락

초록

감광성 고분자를 감지막 재료로 한 FET(Field Effect Transistor)형 CO₂ 센서를 사진식각법으로 제작하였다. 즉, 바탕소자인 pH-ISFET gate 위에 먼저 Ag/AgCl 기준전극을 형성한 후, 수화젤(hydrogel)막 및 기체투과막의 순서로 감지막을 사진식각법으로 형성하였다. 광가교형 감광성 고분자 polyvinyl alcohol 또는 poly(vinyl pyrrolidinone-co-vinyl acetate)를 감지막의 재료로 할 경우에는 사진식각법으로 용매를 포함하는 일정두께의 수화젤막을 형성하는 것이 어려운 것으로 판단되었다. 광중합 감광성 고분자로서 2-hydroxy metha-crylate, acrylamide 단량체를 수화젤막 재료로, polyurethane acrylate oligomer를 기체투과막의 재료로써 사용할 경우 사진식각법으로 용이하게 막의 형성이 가능하였고, 제조된 FET형 CO₂ sensor는 CO₂ 농도 10^-3∼10⁰ mole/ℓ에서 좋은 직선성을 나타내었다.

A FET(Field Effect Transistor) type dissolved CO₂ sensor based on Severinghaus type CO₂ sensor was fabricated by the photolithographic process. The sensor consists of Ag/AgCl reference electrode and membranes (hydrogel membrane and CO₂ gas permeable membrane) on the pH-ISFET base chip. Ag/AgCl reference electrode was fabricated as follows. Ag layer was thermally evaporated and then its upper surface was chemically chloridized into the AgCl. The hydrogel used as an internal electrolyte solution was fabricated by a photolithographic method using 2-hydroxyethyl methacrylate(HEMA) and acrylamide. CO₂ permeable membrane on the top of the hydrogel layer was formed by photolithographic process with UV-oligomer. The FET type pCO₂ sensor fabricated by photolithographic method showed good linearity within the concentration range of 10^-3∼10⁰mole/ℓ of dissolved CO₂ in aqueous solution with high sensitivity.

[References]

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[1] Stow RW, Baer RF, Randall BF, Arch. Phys. Med., 38, 646 (1957)

[2] Severinghaus JW, Bradley AF, J. Appl. Physiol., 13, 515 (1958)

[3] Tsukada K, Miyahara Y, Shibata Y, Miyagi H, Sens. Actuators B-Chem., 2, 291 (1990)

[4] Schelter W, Gumbrecht W, Montag B, Sens. Actuators B-Chem., 6, 91 (1992)

[5] Vanden Berg A, VerderSchoot BH, De Rooij NF, Sens. Actuators B-Chem., 13, 340 (1993)

[6] Wolf S, Tauber RN, Silicon Processing for the VLSI Era, Lattice Press, 1, 421 (1986)

[7] Hatzatcis M, Canavello BJ, Shau JM, IBM J. Res. Develop., 24, 452 (1980)

[8] Schepel SJ, de Rooij NF, Coning GR, Oeseburg B, Zijlstra WG, Med. Biol. Eng. Comput., 22, 8 (1984)

[9] Gernet S, Koudelka M, De Rooij NF, Sens. Actuator, 18, 59 (1989)