back to article Photoplethysmography up

Photoplethysmography is the next big thing in wearables, says TrendForce. For the uninitiated, photoplethysmography is technology that uses LEDs to measure pulse rate and blood oxygen concentration. TrendForce reckons reflective photoplethysmography (PPG) sensors are "gradually becoming an integral part of most wearable …

  1. Suricou Raven


    I already have an internal sensor for blood carbon dioxide level, and can get a pulse rate just by touching the side of my neck.

    1. Anonymous Coward
      Anonymous Coward

      Re: Why?

      I suppose it would be useful as an alarm in case you had restricted oxygen due to a carbon monoxide getting into the passenger cabin of your car, because you won't know it until you lose consciousness. But yeah, it isn't like its useful for workouts in the way tracking heart rate is.

      1. Cynical Observer

        Re: Why?


        In such a scenario, I'd want an alarm a damn sight sooner than when my body is already shutting down. As I understand it, the problem with carbon monoxide poisoning is that it overwhelms you pretty quickly - by the time you realise you have an issue, it may well be too late/difficult to react.

        1. Suricou Raven

          Re: Why?

          This sensor is also not going to do you a lot of good on carbon monoxide: It binds to the blood in just the same way as oxygen does. An optical sensor would have a very hard time telling them apart.

        2. Anonymous Coward
          Anonymous Coward

          @Cynical Observer

          Sure, you'd want an alarm sooner, and it would be foolish not to have a carbon monoxide detector in your house, but not everywhere you go (such as your car) has such a detector in place. Better to be alerted in the last minute, than not at all.

          Well, that's providing the optical sensor can detect carbon monoxide since there seems to be some skepticism. I don't know enough to say one way or another.

      2. DocJames

        Re: Why?

        A doctor writes...

        it would not be useful for excluding CO poisoning; it is a standard error to avoid relying on O2 saturation monitors if suspected. As pointed out above (and then mysteriously downvoted) the spectra absorbed are identical between oxyhaemoglobin and carboxyhaemoglobin, and very different to deoxyhaemoglobin.

        You need a blood gas analyser if you wish to exclude CO poisoning in vivo. Not some fancy colour changing tee-shirt.

    2. BurnT'offering

      Re: Why?

      Sometimes it's useful to have a 2nd opinion: yes, I really am dead

  2. raving angry loony

    Two sides.

    I can see many applications for this stuff for people with a variety of medical issues.

    Any bets it'll mainly be used by more or less healthy people who feel that the world needs to see this information as a constant data stream?

    Must be Friday? Oh, yes, it is Friday in Blighty. Started the drinking a little earlier I see.

    ps: how about a "dateline" tag on articles so we can see if it was delivered by the UK or US or (other) office?

  3. MrDamage Silver badge



  4. Alister

    Yet another way to worry hypochondriacs and annoy GPs.

    "Doctor, Doctor, My Smartband says my blood oxygen level is 70%"

    "Yes, yes, if it was true, you'd be unconscious by now, Mrs Smith"

    There's a reason proper Pulse-Oximeters cost a lot of money.

    1. Anonymous Coward
      Anonymous Coward

      Cost of oximeters

      Not so much. My digital (finger- worn) pulse/oximeter cost CDN$80, and is accurate to 2 percent oxygen saturation compared to those used in the hospitals.

  5. Anonymous Coward
    Anonymous Coward

    There's a reason proper Pulse-Oximeters cost a lot of money.

    Define "a lot"? You can get them online for around £35 or so, and that's buying local - buying at source in China will probably be 1/5th of that, but you'd have to buy a container full of them.

    I must look up how the oxygen part actually works. The finger heartbeat sensing I already did 35 years ago with a small bulb, an LDR and some electronics :).

    1. Alister

      Define "a lot"? You can get them online for around £35 or so

      Note I said "proper".

      A professional Pulse-Oximeter as used by the medical profession is likely to be £150 - £200 or more.

      Anything cheaper is likely to be inaccurate, or unable to compensate for patient movement or circulatory variations.

      The "oxygen bit" at it's most basic measures the "redness" of the blood in the capillaries - which can be correlated to the oxygen saturation. In practice, it's a bit more involved than that though...

      1. Jason Bloomberg Silver badge

        A professional Pulse-Oximeter as used by the medical profession is likely to be £150 - £200 or more.

        Anything cheaper is likely to be inaccurate, or unable to compensate for patient movement or circulatory variations.

        A lot of the cost in professional medical kit seems to be a premium added because it is certified for medical use and to cover all which goes with that with a small market.

        Non-medical equipment may be less accurate, but that's not necessarily inaccurate to any appreciable degree outside a clinical environment. My GP and healthcare workers all seem to find using equipment one can buy off the shelves in a high-street chemist acceptable enough.

        They are good enough for most cases, don't need to be perfect, just good enough to indicate when things are amiss which should then be checked out more accurately.

        1. DocJames

          A doctor writes some more...

          What Jason said.

          Except I don't see why anyone* would want to measure their sats outside a hospital. I don't really even find the GP measured sats useful - it rarely influences the decision for hospital assessment. It may be useful in the "theatre" of doctoring - here is a shiny machine! It says ping! It says you do not need to go to hospital! [Patient leaves happy they required not *just* their GP, but also a shiny machine saying ping]. I'd be interested in the views of GPs (if any are out there...)

          People can tolerate very low sats if there is a gradual trend - on summiting Everest they're usually in the 70s... which given that a hospital will panic if less than 92% in a normal person is quite a drop (I'd actually start to worry at 94% in a truly healthy person). If you were subjected to that acutely you'd pass out, and not wake up until the O2 was cranked back up. Those with cyanotic heart disease can often be walking around with sats in the 70s, albeit they look a little blue around the edges.

          Finally I would like to commend the 2015 (I think) Australasian oxygen guidelines to any clinicians out there, as they happily accept targeting O2 sats much lower than other guidelines due to the dangers of hyperoxia.

          * except those with COPD (smoking related lung disease) - it may help decide when to visit your GP.

  6. Mage

    Carbon Monoxide

    Gives a lovely colour.

    Carbon dioxide and carbon monoxide have different effects. Smokers have higher monoxide levels in their breath even when they are not smoking.

    1. Charles Augustus Milverton

      Re: Carbon Monoxide

      Not always so. When I was a 50 a day man my doctor found my carbon monoxide level was barely measurable. The secret is to suck hard to get better combustion !

  7. jake Silver badge

    Dumbasses are dumbasses ...

    ... marketards exist to separate fools from their money.

    The entire "fitness wearable" fad is a complete laugher :-)

    (Note: that includes shoes & clothing, BTW ... )

  8. David 132 Silver badge

    Are we playing Headline Scrabble here or something?

    Admit it Mr Sharwood, you've been waiting your whole journalistic career for an opportunity to use the word "photoplethysmography" in a headline, right?

    1. Fibbles

      Re: Are we playing Headline Scrabble here or something?

      Presumably that's why the article is less than 70 words...

      1. raving angry loony

        Re: Are we playing Headline Scrabble here or something?

        Maybe he gets paid (or earns bonuses) by the article rather than by the word?

        Now introducing "articles for Twitter"... coming soon.

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