Talk:CO2 Concentration Detector - Revision history

Zhaoyun: /* Results and Analysis */

2025-04-29T11:22:34Z

Results and Analysis

← Older revision		Revision as of 19:22, 29 April 2025
Line 91:		Line 91:
	* ''c'': CO<sub>2</sub> concentration (in %)		* ''c'': CO<sub>2</sub> concentration (in %)

	[[File:1745923203643.png\|~~left~~\|300px\|CO<sub>2</sub> Concentration vs. Photodetector Output Voltage]]		[[File:1745923203643.png\|center\|thumb\|300px\|CO<sub>2</sub> Concentration vs. Photodetector Output Voltage]]

	== Analysis ==		== Analysis ==

Zhaoyun: /* Results and Analysis */

2025-04-29T11:22:10Z

Results and Analysis

← Older revision		Revision as of 19:22, 29 April 2025
Line 91:		Line 91:
	* ''c'': CO<sub>2</sub> concentration (in %)		* ''c'': CO<sub>2</sub> concentration (in %)

	[[File:1745923203643.png\|left~~\|thumb~~\|300px\|CO<sub>2</sub> Concentration vs. Photodetector Output Voltage]]		[[File:1745923203643.png\|left\|300px\|CO<sub>2</sub> Concentration vs. Photodetector Output Voltage]]

	== Analysis ==		== Analysis ==

Zhaoyun: /* Results and Analysis */

2025-04-29T11:21:24Z

Results and Analysis

← Older revision		Revision as of 19:21, 29 April 2025
Line 91:		Line 91:
	* ''c'': CO<sub>2</sub> concentration (in %)		* ''c'': CO<sub>2</sub> concentration (in %)

	[[File:1745923203643.png\|~~center~~\|thumb\|300px\|CO<sub>2</sub> Concentration vs. Photodetector Output Voltage]]		[[File:1745923203643.png\|left\|thumb\|300px\|CO<sub>2</sub> Concentration vs. Photodetector Output Voltage]]

	== Analysis ==		== Analysis ==

Zhaoyun: /* Procedure */

2025-04-29T11:20:40Z

Procedure

← Older revision		Revision as of 19:20, 29 April 2025
Line 27:		Line 27:
	* A narrow-band optical filter centered at 4.26 μm was placed before the photodetector to ensure only light at this wavelength reached the sensor.		* A narrow-band optical filter centered at 4.26 μm was placed before the photodetector to ensure only light at this wavelength reached the sensor.
	* A photodetector (light intensity sensor) was connected to a data acquisition system, which recorded the output voltage corresponding to the detected light intensity.		* A photodetector (light intensity sensor) was connected to a data acquisition system, which recorded the output voltage corresponding to the detected light intensity.
	[[File:07e559e7cb1ccaf8d405442afb2907c.jpg\|thumb\|250px\|System Setup]]		[[File:07e559e7cb1ccaf8d405442afb2907c.jpg\|center\|thumb\|250px\|System Setup]]

	# '''Initial Measurement'''		# '''Initial Measurement'''

Zhaoyun: /* Results and Analysis */

2025-04-29T11:20:22Z

Results and Analysis

← Older revision		Revision as of 19:20, 29 April 2025
Line 91:		Line 91:
	* ''c'': CO<sub>2</sub> concentration (in %)		* ''c'': CO<sub>2</sub> concentration (in %)

	[[File:1745923203643.png\|thumb\|300px\|CO<sub>2</sub> Concentration vs. Photodetector Output Voltage]]		[[File:1745923203643.png\|center\|thumb\|300px\|CO<sub>2</sub> Concentration vs. Photodetector Output Voltage]]

	== Analysis ==		== Analysis ==

Zhaoyun: /* Conclusion */ new section

2025-04-29T11:19:49Z

Conclusion: new section

← Older revision		Revision as of 19:19, 29 April 2025
Line 100:		Line 100:
	=== System Imperfections and External Influences ===		=== System Imperfections and External Influences ===
	Due to limitations in the experimental setup, complete gas sealing could not be achieved, potentially causing gas leakage or imperfect mixing. In addition, uncontrolled external infrared sources may have introduced optical noise into the system, affecting the sensor output. This optical interference is one of the main contributors to measurement uncertainty and reduces the system’s repeatability and precision.		Due to limitations in the experimental setup, complete gas sealing could not be achieved, potentially causing gas leakage or imperfect mixing. In addition, uncontrolled external infrared sources may have introduced optical noise into the system, affecting the sensor output. This optical interference is one of the main contributors to measurement uncertainty and reduces the system’s repeatability and precision.

			== Conclusion ==

			In this project, we successfully developed a CO<sub>2</sub> sensing system based on infrared absorption at the characteristic wavelength of 4.26 μm. By monitoring the voltage output of a photodetector and analyzing its response to varying CO<sub>2</sub> concentrations, we demonstrated a clear and repeatable inverse correlation between gas concentration and detector output.

			Although minor deviations were observed—primarily due to environmental noise, limited gas sealing, and optical interference—the overall results confirmed the system's sensitivity to CO<sub>2</sub> levels. The fitted exponential model further validated the expected behavior derived from the Beer–Lambert law.

			Despite inherent measurement uncertainties, the system reliably responded to changes in CO<sub>2</sub> concentration, indicating the successful realization of a functional gas sensor prototype.

Zhaoyun: /* Results and Analysis */

2025-04-29T11:19:01Z

Results and Analysis

← Older revision		Revision as of 19:19, 29 April 2025
Line 91:		Line 91:
	* ''c'': CO<sub>2</sub> concentration (in %)		* ''c'': CO<sub>2</sub> concentration (in %)

	[[File:1745923203643.png~~\|center~~\|thumb\|300px\|CO<sub>2</sub> Concentration vs. Photodetector Output Voltage]]		[[File:1745923203643.png\|thumb\|300px\|CO<sub>2</sub> Concentration vs. Photodetector Output Voltage]]

	== Analysis ==		== Analysis ==

Zhaoyun: /* Results and Analysis */

2025-04-29T11:18:41Z

Results and Analysis

← Older revision		Revision as of 19:18, 29 April 2025
Line 91:		Line 91:
	* ''c'': CO<sub>2</sub> concentration (in %)		* ''c'': CO<sub>2</sub> concentration (in %)

	[[File:~~co2_voltage_plot~~.png\|center\|thumb\|300px\|CO<sub>2</sub> Concentration vs. Photodetector Output Voltage]]		[[File:1745923203643.png\|center\|thumb\|300px\|CO<sub>2</sub> Concentration vs. Photodetector Output Voltage]]

	== Analysis ==		== Analysis ==

Zhaoyun: /* Results and Analysis */ new section

2025-04-29T11:17:11Z

Results and Analysis: new section

← Older revision		Revision as of 19:17, 29 April 2025
Line 40:		Line 40:
	* The voltage outputs ''V<sub>0</sub>'' (initial) and ''V'' (at each CO<sub>2</sub> level) were systematically recorded.		* The voltage outputs ''V<sub>0</sub>'' (initial) and ''V'' (at each CO<sub>2</sub> level) were systematically recorded.
	* A calibration curve was plotted with CO<sub>2</sub> concentration on the x-axis and photodetector output voltage on the y-axis, representing the detection characteristic.		* A calibration curve was plotted with CO<sub>2</sub> concentration on the x-axis and photodetector output voltage on the y-axis, representing the detection characteristic.

			== Results and Analysis ==

			The following tables present the measured output voltages from the photodetector corresponding to different CO<sub>2</sub> concentrations. Each voltage value represents an individual measurement, and an average is calculated from three groups.

			{\| class="wikitable"
			! Time (s) !! CO<sub>2</sub> (%) !! Group 1 (mV) !! Group 2 (mV) !! Group 3 (mV)
			\|-
			\| 0 \|\| 0.042 \|\| 241.9 \|\| 238.0 \|\| 237.6
			\|-
			\| 1 \|\| 32 \|\| 233.1 \|\| 215.9 \|\| 223.3
			\|-
			\| 2 \|\| 48 \|\| 176.0 \|\| 166.6 \|\| 173.6
			\|-
			\| 3 \|\| 58 \|\| 165.6 \|\| 160.8 \|\| 156.6
			\|-
			\| 4 \|\| 65 \|\| 149.7 \|\| 155.4 \|\| 156.7
			\|-
			\| 5 \|\| 70 \|\| 139.0 \|\| 143.0 \|\| 139.3
			\|-
			\| 6 \|\| 73 \|\| 129.0 \|\| 132.2 \|\| 129.1
			\|-
			\| 7 \|\| 76 \|\| 132.7 \|\| 129.4 \|\| 133.7
			\|-
			\| 8 \|\| 79 \|\| 121.2 \|\| 115.7 \|\| 125.6
			\|-
			\| 9 \|\| 81 \|\| 120.5 \|\| 115.5 \|\| 121.6
			\|-
			\| 10 \|\| 82 \|\| 116.0 \|\| 114.2 \|\| 114.6
			\|-
			\| 11 \|\| 83 \|\| 110.7 \|\| 113.1 \|\| 113.0
			\|-
			\| 12 \|\| 84 \|\| 107.7 \|\| 107.6 \|\| 108.2
			\|-
			\| 13 \|\| 85 \|\| 104.7 \|\| 102.3 \|\| 102.4
			\|-
			\| 14 \|\| 86 \|\| 99.0 \|\| 101.4 \|\| 100.8
			\|}

			''Table: Raw voltage measurements across three groups''

			We use the averaged voltage response as a function of CO<sub>2</sub> concentration:

			<math>
			V(c) = 280.45 \cdot e^{-0.01057 \cdot c}
			</math>

			where:
			* ''V'': output voltage (in mV)
			* ''c'': CO<sub>2</sub> concentration (in %)

			[[File:co2_voltage_plot.png\|center\|thumb\|300px\|CO<sub>2</sub> Concentration vs. Photodetector Output Voltage]]

			== Analysis ==

			=== Nonlinear Voltage Response to CO<sub>2</sub> Concentration ===
			The relationship between output voltage and CO<sub>2</sub> concentration is not strictly linear. In the low concentration range (e.g., from 0.042% to around 30%), the voltage drops slowly, whereas at higher concentrations the decline becomes significantly steeper. This behavior can be attributed to the logarithmic nature of infrared absorption and the nonlinear response of the photodetector—where sensitivity increases as light intensity decreases.

			=== System Imperfections and External Influences ===
			Due to limitations in the experimental setup, complete gas sealing could not be achieved, potentially causing gas leakage or imperfect mixing. In addition, uncontrolled external infrared sources may have introduced optical noise into the system, affecting the sensor output. This optical interference is one of the main contributors to measurement uncertainty and reduces the system’s repeatability and precision.

Zhaoyun: /* Procedure */

2025-04-29T11:16:02Z

Procedure

← Older revision		Revision as of 19:16, 29 April 2025
Line 27:		Line 27:
	* A narrow-band optical filter centered at 4.26 μm was placed before the photodetector to ensure only light at this wavelength reached the sensor.		* A narrow-band optical filter centered at 4.26 μm was placed before the photodetector to ensure only light at this wavelength reached the sensor.
	* A photodetector (light intensity sensor) was connected to a data acquisition system, which recorded the output voltage corresponding to the detected light intensity.		* A photodetector (light intensity sensor) was connected to a data acquisition system, which recorded the output voltage corresponding to the detected light intensity.
	[[File:~~1745923203643~~.~~png~~\|thumb\|250px\|System Setup]]		[[File:07e559e7cb1ccaf8d405442afb2907c.jpg\|thumb\|250px\|System Setup]]

	# '''Initial Measurement'''		# '''Initial Measurement'''