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  • Author Author: fustini
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Biosensor crunch time

fustini

Our biosensor array team worked late into the night on Saturday at Pumping Station: One.  With the hackerspace challenge build deadline on Tuesday night, it's definately crunch time!

 

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Thankfully we've got a nice array of working sensors (in the order of signal speed):

 

  • EKG
  • Pulse oximeter
  • GSR (Galvanic Skin Response)
  • CO2
  • Temperature

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Dan yet again played the role of test subject:

 

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The QRD1114QRD1114 sensor from SparkFun contains an IR LED and a compatible phototransistor.  It dectects pulse via the change in the amount of infrared light reflected by finger as blood pumps through it.

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We observed a great correlation between EKG and pulse oximetry signals:

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Cheers,

Drew

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  • Very interesting, I want to build something like this to monitor BP,PR,temp, and oxygen level with the addition of a way to record all of these things when they are off normal. With A-fib sometimes my BP drops, and my PR goes skyhi and bounces all over the place from 98 to 170. Sometimes for only a couple minutes sometimes for hours. I can tell when it's out of whack but it would be nice to be able to monitor it. Thanks for your comments. ron5329

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  • Very interesting, I want to build something like this to monitor BP,PR,temp, and oxygen level with the addition of a way to record all of these things when they are off normal. With A-fib sometimes my BP drops, and my PR goes skyhi and bounces all over the place from 98 to 170. Sometimes for only a couple minutes sometimes for hours. I can tell when it's out of whack but it would be nice to be able to monitor it. Thanks for your comments. ron5329

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  • in reply to Former Member

    Hi Ron,

     

       I think what you are facing is an arrhythmic condition. Probably tachycardia. A pulse rate monitor doesn't give you insights to what kind of arrhythmia you are facing. It can be due to Ventricular issues or Atrial issue (It can also be atrial flutters). What you need is a holter monitor (Record full ECG for longer period of time). You can build a cheap ECG monitor using ADS1292 (Texas Instruments), MAX30001( Maxim Integrated) or AD8232 (Analog  Devices). Cuffless BP monitors are still under R&D phase. Cuff-based BP monitors will have low temporal resolution. But once in every minute will do the job. ( If you are interested to do some research you can read up on using PPG (The raw waveforms from Pulse Ox meters) and ECG to monitor BP. Calculate pulse transit time and pulse arrival time and using these you can estimate BP with calibration.

     

    MIT-BIH has a lot of annotated ECG database. You can train a system using that and perform inference on your ECG monitor to classify the Arrhythmia.

     

    If you are looking for cardiac damage look at ST Elevation/ Depression. From ECG you can derive this parameter. If you are facing cardiac tissue damage due to lack of oxygen supply to the heart muscles (Ischemia) it will reflect on your ST values.

     

    SpO2 (Relative oxygen saturation) or oxygen level as you mentioned is actually a measure of your lung function. SpO2 is measured at places where you have a lot of arterioles (like finger tips or earlobes). If blood carries enough oxygen the SpO2 value will be above 95. If its less than 90 something is going wrong with your lungs.

     

    I recently wrote an article on how to use MAX30100 PPG(photoplethysmograph) sensor with BeagleBone black. Oxygen Saturation - SpO2 Measurement

    It's not really well written but I explained the steps there.

     

    Note: I assume that you are already consulting a cardiologist on the problem you have explained. If not thats something you should do at the earliest.

     

    I will be happy help you. I am a biomedical engineer with research experience.

     

    Regards.

    Aswin