Title :
Development of non-invasive optical transcutaneous pCO2 gas sensor and analytic equipment
Author :
Lee, Hwan-Joo ; Kim, Do-Eok ; Kwon, Dae-Hyuk ; Lee, Seung-Ha ; Kang, Shin-Won
Author_Institution :
Dept. of Electron. Eng., Kyungpook Nat. Univ., Daegu, South Korea
Abstract :
We have studied the development of an optical transcutaneous pCO2 gas sensor and analyzer using a non-invasive method. The basic principle of the pCO2 measurement adapted Beer-Lambert´s law and the embodied system using the NDIR (non dispersive infrared) method. CO2 gas reacts with a 4.3 μm wavelength, so we selected this wavelength by an optical filter, and used energy decrease by molecule oscillations. We measured the CO2 concentration using the MFC (mass flow controller) in basic steps instead of the pCO2 gas that can collect by inflicting heat on the outer skin. This measuring system consisted of an IR lamp, an optical filter, an optical reaction chamber, a pyroelectric sensor and a signal processing system. We minimized the volume of the optical reaction chamber in order to make the sensor portable. We made an optical reaction chamber with a Si wafer using MEMS technology and it was shortened to 1 mm. We carried out an experiment in photoreaction length variation from 1 mm to 10 mm. We confirmed the linear graph of CO2 concentration variation from 1,000 ppm (parts per million) to 100,000 ppm at 1 mm photoreaction length. The response time of this system was within 2 seconds, which is fairly fast.
Keywords :
biomedical equipment; blood; gas sensors; light absorption; optical filters; 1 to 10 mm; 4.3 micron; Beer-Lambert law; CO2; IR lamp; MEMS technology; Si; carbon dioxide gas sensor; mass flow controller; nondispersive infrared method; noninvasive optical transcutaneous gas sensor; optical filter; optical reaction chamber; pyroelectric sensor; signal processing system; Dispersion; Fluid flow measurement; Gas detectors; Optical filters; Optical sensors; Optical signal processing; Skin; Temperature control; Wavelength measurement; Weight control;
Conference_Titel :
Sensors, 2004. Proceedings of IEEE
Print_ISBN :
0-7803-8692-2
DOI :
10.1109/ICSENS.2004.1426271