Thermopile sensors are often confused with PIR sensors because both detect infrared. However, they operate on different principles and serve different purposes. This article clarifies the differences.<\/p>\n
Principle:<\/strong> Pyroelectric effect \u2013 generates charge in response to changes<\/em> in temperature. Differential dual-element design cancels common-mode signals.<\/p>\n Output:<\/strong> Typically digital (motion yes\/no) or analog AC-coupled signal.<\/p>\n What it measures:<\/strong> Change in IR over time (derivative).<\/p>\n Applications:<\/strong> Motion detection, occupancy sensing.<\/p>\n Principle:<\/strong> Seebeck effect \u2013 multiple thermocouples in series generate voltage proportional to temperature difference between target and sensor.<\/p>\n Output:<\/strong> Analog voltage (DC) proportional to absolute temperature of target (or temperature difference).<\/p>\n What it measures:<\/strong> Absolute IR intensity (temperature).<\/p>\n Applications:<\/strong> Non-contact thermometers, thermal cameras (array), oven temperature sensing.<\/p>\n Yes, but indirectly. If a warm object moves across the field of view of a thermopile, the output voltage will change. However, thermopiles are slower and less sensitive to motion than PIR. They are not optimized for motion detection.<\/p>\n No. PIR sensors are intentionally AC-coupled to ignore constant IR. They cannot give an absolute temperature reading.<\/p>\n Both technologies have array versions: PIR arrays (rare) and thermopile arrays (common, e.g., MLX90640, AMG8833). Thermopile arrays create low-resolution thermal images (8\u00d78 to 32\u00d724 pixels) used for presence detection, people counting, and fever screening.<\/p>\n PIR and thermopile sensors are complementary. PIR excels at low-power motion detection; thermopile provides temperature data. Choose based on your application’s primary need.<\/p>\n","protected":false},"excerpt":{"rendered":" Introduction Thermopile sensors are often confused with PIR sensors because both detect infrared. However, they operate on different principles and serve different purposes. This article clarifies the differences. PIR (Passive Infrared) \u2013 Motion Detection Principle: Pyroelectric effect \u2013 generates charge in response to changes in temperature. Differential dual-element design cancels common-mode signals. Output: Typically digital […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-3005","post","type-post","status-publish","format-standard","hentry","category-news"],"blocksy_meta":[],"yoast_head":"\r\nThermopile \u2013 Temperature Measurement<\/h2>\n
Key Differences<\/h2>\n
\n\n
\n \nAspect<\/th>\n PIR<\/th>\n Thermopile<\/th>\n<\/tr>\n<\/thead>\n \n Signal<\/td>\n AC-coupled (responds to change)<\/td>\n DC (responds to absolute)<\/td>\n<\/tr>\n \n Detects stationary objects?<\/td>\n No<\/td>\n Yes (temperature)<\/td>\n<\/tr>\n \n Typical use<\/td>\n Motion<\/td>\n Temperature<\/td>\n<\/tr>\n \n Elements<\/td>\n Dual (differential)<\/td>\n Single or array<\/td>\n<\/tr>\n \n Cost<\/td>\n Low<\/td>\n Moderate<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Can a Thermopile Detect Motion?<\/h2>\n
Can a PIR Measure Temperature?<\/h2>\n
Array Sensors: Thermal Cameras<\/h2>\n
Which One Do You Need?<\/h2>\n
\n
Conclusion<\/h2>\n