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Design of Contactless Thermometer:
In view of the rising demand for contactless clinical thermometers, their unavailability and spiralling market prices in India, CDAC Mohali has taken the initiative to design a low cost, low power contactless forehead thermometer. As part of the national initiative to meet the COVID-19 challenge, the design is being released ‘Free of Cost’, for any interested manufacturer to take up production and help serve the humanity in this hour of need.

Brief details of the system follow. To download the design files, please Apply here.

Principle:
Every physical body above absolute zero (-273C), emits infra red (IR) radiation depending on its temperature. Using suitable sensitive sensor, the emitted waves from given object can be used to measure the temperature of an object.

The proposed thermometer works by focusing IR radiation coming from the object onto a detector. The detector here is an array of thermopile, which generates a voltage proportional to the radiation received. This voltage is sampled and processed to estimate the temperature of the object. This temperature is displayed on the screen in required units.

Thus, temperature of the forehead can be quickly measured without making a physical contact with the object.

Needless to say this thermometer enables

  1. Accurate measurement for estimation of subjects health (fever)
  2. Measurement from safe distancing (conforming to the need of social distancing)
  3. Avoiding contamination of the system
System design

The thermometer design is quite straight forward. The output from the IR thermopile is given to a low power microcontroller that processes it. It drives a small OLED display to indicate the temperature. The block diagram and features of the system are given below:

Contactless Thermometer

Features:
  1. Handheld battery operated device designed with an easily available low cost microcontroller
  2. Low power OLED Display
  3. Operating Current: less than 2mA; (battery life several months)
  4. Calibrated in wide temperature range: 0 to 100 °C.
  5. Accuracy of 0.1°C (in clinical range of temperatures)
  6. Measurement resolution of 0.01°C
  7. Auto power off feature
  8. Single switch operation
  9. Easy to manufacture and low maintenance design




The detailed product design including the following and are available for free download.
  1. Product Design (Circuit design and schematic)
  2. Hex code for microcontroller (ATMega 328)
  3. PCB layout design (two layered PCB size 30 x 86mm; uses SMD components 806 package).
If required, 3D Printer design (STL file) of the enclosure can also be provided.

To download the design files, please Apply here.

Designed and developed by :

Sh. Shailesh Singh,
Principal engineer,EECD,
CDAC, Mohali.

www.cdac.in


DISCLAIMER: The design is provided free of cost, in the best interest of the nation/ humanity. CDAC, Mohali assumes no liabilities, whatsoever, in this matter.