Can AFE4400 be used for the body surface such as wrist or arm?

Hello,

AFE4400 have been used for wrist based heart rate monitoring applications.

Please follow the article below that describes the components that make up a wrist based heart rate monitor.

It also shows the components that connects to the AFE4400.

http://electronicdesign.com/digital-ics/build-wrist-heart-rate-monitor-using-ultra-low-power-mcu

We use the refraction to take the PPG signal from wrist, but the signal is weaker than the finger. If I inrease the gain of AFE4400 to enlarge the PPG signal, there will be an issue that dc signal will exceed the ADC full-scale voltage(1.2V).

So I don't know if AFE4400 is designed using in wrist for sampling PPG signal. It will be difficult that how to deal with dc signal in PPG.

Plesase give some advice!

The AFE4400 can be used anywhere on the body. Can you help me understand your application better by giving me some more information?

Are you trying to measure heart rate on the wrist or measure SpO2?

Can I get snapshots of the AFE register settings and the PPG waveform that you measured on the wrist? The more information the better. Also note the setup you used with each snapshot.

What LED and Photodiode sensors are you using for you application? The quality of the PPG signal is also dependent on the sensors used.

Are you taking the PPG signal from your wrist and finger or were there multiple people? If so, were the results the same?

Just checking in. I haven't heard a response so I was wondering if you were able to solve these issues.

I have a recent project with EEG signal processing. I would like to use the part ADS1298 for signal reception. My doubt is that " is there is any external Amplifiers should we use between body and IC? for the entire EEG Leads. or we can connect it directly / is there is any extra amplifiers need for RLD signal out.....? ." if so please help me to find it out

Thanks in advance

Sanal Joseph

Hello, I'm also trying to measure HR on the arm. Signal seems very small. I'm using a reflective method. One question we connect phototransitors or photodiodes. Does there exist a specs on what the inputs should be to be able to detect a signal?

Thanks,

Hiroshi,

Are you using the AFE4400, AFE4490, or the ADS1298? There has been some posts on 3 different devices and I'm unsure which one you are referring to.

For the AFE devices, we can measure heartrate on the arm and wrist. In reflective applications using a single LED, one of the LEDs is replaced with the Green LED and the other LED is removed. For example, the IR LED can be replaced with the Green LED and the red LED can be removed from the design. In the AFE register settings, the current for the red LED can be turned off.

Depending on the configuration used, maintain the H-Bridge supply or the external supply voltage for the LED.

Recommended operating condition for LED_DRV_SUP

    in H-Bridge configuration is max (3V, (1.4V + Vled + Vcable)) to 5.25V
    in Common Anode configuration is max (3V, (1.3V + Vled + Vcable)) to 5.25V

Amy,

I noticed that in some designs both red and green LEDs are used together: one green LED between two RED LEDs. I am wondering this approach affects the accuracy or not?

Moreover, I noticed that optical HRM is very sensitive to motion and according to the documentations of your board, it is better to be still. I am wondering if there is any way to deal with this issue? I need to extract the HR during exercise.

Thank you.

Hello,

We did not succed to buy the wrist EVM, only the finger EVM.

I notice that the red/IR are very sensible to the external light when using your EVM. When the finger probe is a few open it is impossible to see any HR signal.

Could it be possible to know you green led reference to test them please?

BR

Mich

Farshad,

Can you describe the application you are referring to a little more?

Using a Red and a Green LED should not affect the accuracy since the sampling of the LED signals will be time multiplexed.

What will you be doing with the Red and Green LED phase data? Can you provide us a reference design for this application?

Yes, it is better to be still when taking data. HRM is sensitive to motion.

I want to measure the HR by reflection. Only one led is ok. I only want to test some leds, so the reference request.

I noticed in your previous post that for reflection you used a green led so I am interrested by these references (emetter and recepter).

Mich,

More information about using a green LED can be found on the following e2e thread.

http://e2e.ti.com/support/applications/high_reliability/f/30/t/276162.aspx

Dear Amy,

I am wondering if it is possible to connect an accelerometer to the AEF4400 chip in the evaluation board? Indeed, I wanna remove the motion noise.

Is there any reference (schematic, code) from TI for that?

Thanks a lot

Our Health hub uses an accelerometer and the source code of the HRM reference design can be requested from the following link:

http://www.ti.com/lit/pdf/tida010

The design files to build the development board can be downloaded from the following link:

http://www.ti.com/litv/zip/tidc057

The EVM has footprint for MPU9150(accelerometer) at U6 location.  You can install it to track motion.  Sorry we have no code to share for it. 

Hello Praveen Aroul，

Sorry to bother you .

    I designed two boards according to TI"s  blood oxygen saturation. one board uses  transmission type sensor,while another uses  reflective sensor. The Schematic diagram and  program of the two boards are the same.

   Everytime I try to collect waveform by the board which use transmission type sensor, I can collect signal easily. The signal just like :

But when I try to collect waveform by the board which use reflective sensor, sometimes I can get the signal ,but more often than, I can't  get  the  signal. the signal just like:

The above three figure are got by the same configuration .So I think  njl 5501 is too sensitive   causing the  unstabled signal of spo2.  The strength of the finger and The distance of the finger with  sensor have an impact on the signal. But I don't know  how  to solve .Hope can get more information.  Thank you very  much .

                            xielinlin

                           2013.3.30

Hello  Praveen Aroul:

          Thank you  for your answer.

           can  I use afe4400  and DCM03  Measuring  blood oxygen saturation？

           can I connect AFE4400 and  DCM03  like 　The following figure？

　　　ｔｈａｎｋ　ｙｏｕ　ｖｅｒｙ　ｍｕｃｈ．

Best Regards．