• State
  • Locked Locked
  • Replies 2 replies
  • Subscribers 47 subscribers
  • Views 784 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LED Brightness/Luminous Intensity for Pulse Oximeter

Mohammad Hosseini1
Intellectual 610 points
Other Parts Discussed in Thread: AFE4490

Hello,

I want to build a reflective pulse oximeter sensor using a Red LED, IR LED, and a Photodiode. I intent to use this sensor with the pulse oximeter I'm building around the AFE4490. This is for a school project.

Are the below types of LEDs appropriate? What brightness level should I look for in the RED LED? Is there any recommended specifications for the types of LEDs and Photodiode to be used with the AFE4490?

I need them to be in a DIP form like the products below.

http://www.sparkfun.com/products/9590

http://www.sparkfun.com/products/528

http://www.sparkfun.com/products/9349

Thanks!

  • 0
    TI__Mastermind 18275 points

    Mohammad,

    We have received your post and hope to have a response back to you soon. 

  • 0
    TI__Mastermind 49176 points

    Hello Mohammad,

    LED forward voltage (VF) and forward current (IF) are the two important parameters that need to be considered as far as LEDs are concerned. Section 7.3 of the AFE4490 datasheet shows the dependence of the LED_DRV_SUP voltage on the VF (VLED).

    The photodiode converts incident light to an electrical signal. The conversion factor is largely dependent
    on the area of the photodiode and its sensitivity at the wavelength of interest. A larger photodiode results in a higher signal current.

    Also for the reflective sensor, you may want to consider the mechanical construction of the setup, placement of LEDs and PD and their distance of separation. All these factors play significant role in getting a quality PPG signal from the measurement site (finger, wrist, arm etc).