ALLPCB
Overview
The COVID-19 pandemic sharply increased demand for temperature measurement products. Infrared thermometers, like masks, became widely used medical devices for epidemic control. Common market names include ear thermometers and forehead thermometers; these devices are typically classified as Class II medical devices.
With rapidly rising production and wider use, reports have emerged that some devices produce inaccurate readings. What causes these inaccuracies, and how can they be addressed? This article analyzes factors that affect the accuracy of infrared thermometers from a product design perspective.
Measurement Methods
Body temperature measurement methods fall into contact and non-contact categories. Contact thermometers mainly use negative temperature coefficient thermistors (NTC). Non-contact thermometers use infrared (IR) sensing:
Industry Distribution and Supply Chain
Infrared thermometer manufacturers in China are concentrated in the Pearl River Delta and Yangtze River Delta, consistent with the regional distribution of the medical device industry. The upstream and downstream supply chain for infrared thermometers includes sensor manufacturers, optical components, calibration equipment, assembly, and testing.
Key Upstream Factors Affecting Accuracy
From an upstream supply chain and design perspective, three critical factors most affect the accuracy of infrared thermometers:
- Infrared sensor performance
- Optical system design
- Calibration system and procedures
Note: This article focuses on thermopile-based infrared detectors used in ear and forehead thermometers. For focal plane array technology, see the paper by Wang Yifeng and Huang Jiangping, "Development of Infrared Focal Plane Detector Array Specifications".
Sensor Example: ZTP148-SR Thermopile
The following uses the commonly encountered Amphenol Advanced Sensors ASTG ZTP148-SR thermopile sensor as an example to analyze how sensor performance affects measurement accuracy.
