Pulse Oximeters; An Amazing Use of Light

Opublikowany 22 maj 2020
You might have been seeing a lot about these little devices lately. Have you ever wondered how they work? Well, let's find out!
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  • Light? Blood? I think you need a CAT scan.

  • 01:18 *Me:* Pauses video, writes it down: "Blood should be kept inside your body". This is going to revolutionize my child daycare (and nightcare) operation in my basement. But what's a suitable replacement for adrenochrome?

  • So be honest with me Doc. Am I going to make it??

  • This is now my go-to video to show my students learning Arduino concepts for the first time how/why we may want to utilize various sensors depending on the context. Great delivery of the concepts in simple language!

  • You know the joke landed well when "that heart thing in your chest" makes me stop and think for a second and a half about what it's called. Well played

  • you know your phone when you put your finger into camera with flashlight does the same shit and its free

  • Another use: when I hiked Mount Kilimanjaro, our guide had a pulse oximeter that we checked regularly to ensure that we were all safe. The slow introduction to altitude makes hypoxia less of a concern (though still possible), but altitude sickness is a very big concern with extended exposure. I doubt the oximeter would catch every case, but regardless we were checked regularly to ensure we were above a certain threshold with emergency oxygen and descent if we didn't. No one in our group needed it, though we did pass someone from another group who was being carried down from the final camp area and we were later told he didn't end up making it.

  • Hi there!

  • Half hour... 8 hours later ;P :) greetings from Poland :) love your humour :)

  • I always wondered why when you shine a bright light through your finger, you can't see any bones. Like, I've got lights that'll shine through my fingers all the way down to my 3rd knuckle. But all I ever see is a steady, red color coming through. No shadows of bones or any other tissues like you see on an x-ray. I guess now that I think about it, it could be due to increased diffusion of the light due to visible light having a longer wavelength than x-rays. That is, the light gets scattered around as bounces from one atom/molecule to another while traveling through your finger, so it comes out evenly from the point it exits and doesn't allow the resolution of any structures within. Where x-rays probably have a small enough wavelength that they don't interact as much with what they're traveling through and aren't dispersed in the same way. But that's just an educated guess.

  • Hi there!

  • I had a surgery yesterday and I had one of theses on and if you touch it, the number changes

  • Ah yes a few days ago I had the (not so much) pleasure to notice one of those on my finger😕... I wondered how they worked and what they were I'm fine now for those who will ask

  • Thank you Takuo Aoyagi!

  • Ya know cause, BLOOD!

  • If someone has a fresh child they should try regularly riding _high_ elevators with them. They should gain a height or at least an air pressure sense! You don't love your children if you're unwilling to provide them with every advantage you can! On second thought: do not provide your children with extra senses, they'll probably turn out obnoxious and since basically everything can potentially harm them, it might even harm them.

  • had some used on me at my last hospital visit (had a stroke with 22 and cleared it without any detectable lasting problems in just 2 weeks), i could imagine most of how it works already but not how it measures the oxygen amount in your blood, thy for sowing me that it also got an infrared diode also aren't the sensoric organs of the human body also technically speaking "man made sensors" ? XD

  • it is funny how we can see infrared while usually you can not

  • I know that hemoglobin molecules can bind with either oxygen or carbon dioxide, and that whichever state it is in determines the light absorption that makes this device work as you describe so clearly. What I don't understand is this: If a high-percentage of hemoglobin is saturated with oxygen, and therefore unavailable to the CO2, what happens to the the CO2 from the tissue cells? if it can't bind with saturated Hemoglobin, how does it get carried back to the lungs? I realize this must have a simple explanation, but I haven't run across it yet. And thanks for making these wonderful videos!

  • My old galaxy S7 had one of these built in next to the camera. It didn't work very well though

    • I remember that, it was almost completely useless

  • The usual el-cheapo used by most med centers uses transverse reflection where the LED and sensor are close to each other. The perpendicular type like the one shown here are more expensive and reliable. The TR types are horribly bothered by your skin. Dry, calloused or cold skin can stop them from working at all.

  • Apple Watch Series 6 anyone?

  • Wow I actually used the science behind this in a quantitative analysis chemistry lab in my uni! We had an unknown mixture of nickel and iron salts and had to perform a calculation on the solution's absorption spectrum at two different wavelengths by comparing it to each salt's known absorption spectrum in order to determine the concentration of nickel and iron ions in solution, just like an oximeter does with oxygenated and de-oxygenated hemoglobin. Never thought I'd see a absorption spectrum graph on this channel!

  • "human ingenuity is awesome" *pans to Michael Revees* I dunno man, seems pretty cursed when left alone.

  • Man... I just wish I had one that could connect to a Wii...

  • Good information but at the same time not. Very conflicted information put out with a disclaimer. At the end of the video it's open ended and that ending it becomes confusing. All that your saying is the progression of technology is cool but don't at this be invested. All your acknowledging is the progression of that tech but you don't take that with a fine grain of salt. At this point just go get a check up and do the follow up check Up's.

  • hypoxia is fun

  • Thanks for the medical advice Doc

  • I'm so mad that I laughed when you shouted "BLOOD!" This channel is so great.

  • What happens when you hold your breath? Does the reading change? If yes, by how? How does it change for trained freedivers who can stay underwater for ten minutes....?

  • The Samsung S6 actually came with a pulse oximeter. I had one and at one doctor's visit we compared its results with the unit she was using and they both showed the same numbers.

  • The way you said Arterial Blood Gas, without flinching, tells me you have never had an ABG performed!

  • now how the heck do carbon monoxide alarms work funny just saw "divebomber" on TCM and they had ones that clamped to the test subjects earlobe

  • As a (real) medical professional myself i enjoyed this Video very much! Great collection of information for everyone!

  • You’d think that after 8 months nobody would notice that at 4:02 you used a “post stroke” intravenous stent as a video. Well, here I am. Not very relevant to the video but I noticed. Here’s my non-cool prize 🏆

  • The reason your fingers are red in front of a bright light is not because of blood, but diffusion. It’s purely the light bouncing around in your fingers and coming out red due to the other kinds of light getting trapped more easily

  • How does a activity bracelet that meters oxygen level differ from this?

  • 99% O2 on Room Air, Pulse 78. This man is healthy AF.

  • Wow, oxygen saturation of 99? That's damn good for your age.

  • I love that Technology Connections has a stock clips budget.

  • DO run out and buy one, because COVID! If you sats drop to around 92 contact your doctor or help line. They drop to 88 call an ambulance. Having one of these allows you to give sats info to medical pro's & can get you the right help in good time.

  • It comes out red because ... blood! Yep, definitely a medical expert. Good solid lol there.

  • Human skin won't reflect the wave length of saturated and unsaturated hemoglobin? Is that true for Brown/ black skin too? I mean Brown is a version of red.

  • Samsung uses it on their phones

  • I hate to be pedantic (im kidding we all love being pedantic), but I really feel like the ear is indeed a sound sensor. If the pressure in the room is increased from 1.0atm to 1.1atm, you might not even notice. If you did notice, it would just feel weird until you popped your ears and then it would feel normal again. You might not even be able to say if the pressure went up to 1.1, or down to 0.9. Thats a garbage pressure sensor. Imagine I turned up the volume on a stereo and you couldnt tell if it got louder or quieter. And then after a few minute you couldnt even hear the music anymore. That would be ridiculous. No, the ear is not a pressure sensor, it only reacts to changing pressure waves (not pressure, pressure waves) in the range 20hz to 20khz. Changing pressure waves in that range is the definition of sound. As you said yourself in your very first video on this channel, "Bell & The Invention of Artificial Sound", at 2:09 quote, "The key to sound is oscillation". Claiming that it is not sound and we are merely 'interpreting' it as sound is claiming that a tree that falls in the woods makes no sound. The falling tree does not vibrate the air, it is totally silent because no brain was there to interpret it. But to be honest, Im not even really arguing the matter at hand, I was just looking for an excuse to leave a comment. I love your videos, especially the one about the dishwasher operation. I learned a lot.

  • I have that exact oximeter... LOL


  • Our ears are actually sensors of sound, not pressure! Our ear reacts to vibrations of particular frequencies in environment, but unable to properly register persistent change in air pressure. Our ears are literally sensors of sound.

  • This device clamps my finger and it's super uncomfortable and irritating to the skin. These devices suck and aren't convenient jk jk jk I'm being as sensative as a pulse oximeter, am I right?

  • Can you PLEASE do a video about the Vein Finder? It’s crazy and I have NO idea how it works... only seen it in practice.

  • Another thing that will make these give erroneous reading is clamping it on the stump of a severed finger. A friend of mine lost a fingertip in an accident a few years ago, and recently put a Pulse Oximeter on his stump to see what it would do. It pretty much declares you to be nearly dead.

  • @3:40 therefore oximeters work poorly on dark skinned people.

  • In case anyone's curious, a good reason to purchase your own pulse oximeter for use at home is if you have a particularly fickle case of a lung condition where at-home monitoring would help. For example, I have asthma. There are days where I feel tired without a very obvious reason, and some of that (though I do have other contributing factors) could be due to an asthmatic reaction. Knowing when/where I tend to get asthmatic reactions helps me narrow down the list of potential sources, which helps me remove asthma triggers from my environment. Pulse oximeters are also useful if you have a young child with severe asthma and you need to monitor their oxygen intake carefully. Not everyone needs a pulse oximeter at home. But for those who do, the low average cost is very nice.

  • 10:20 nice

  • It was because of a pulse oximeter that we knew to send my Aunt to the hospital while she had COVID. Her's was at 75% one night and a nurse told us it may come up and to keep an eye on her. The next day it was 47. We took her straight to the ER and she was put on a ventilator.

  • A pulseOX could have saved Helios Airways Flight 522 if they'd had made them mandatory for all pilots to wear during flights.

  • No you do not really feel temps. See veratasium, or touch a piece of heavy metal and a book in the same room...

  • I have one and the device is truly amazing, if you hold your breath you can see the oxygen level on your blood go down, which is quite awesome.


  • 3:45 hahaha pure genius

  • Thanks for the medical advice, I'm going to give myself brain surgery now 👍

  • oxygenatedly smooth jazz LOL

  • I wonder if his heartrate increases when we boost engagement.

  • Quick! Shine my finger!

  • Let's not forget the best use of a pulse oximeter: the Wii Vitality Sensor.

  • Fascinating. I’ve wondered this a while, but would have never guessed that this was how it worked.

  • I am actually surprised you did no mention that certain cell phones has this sensor installed...

  • I was wondering how my Fitbit knows my heart rate (accurately enough to match what's measured at my doctor office, give or take a couple bpm). I figured it had to do with the weird flashing light on the bottom but other than that, it just seemed to be magic. I'm guessing it's a variant on this tech! Thank you!

  • Haha those bloopers 😂

  • I've used this little device throughout the pandemic to keep my respiratory state in check.

  • I remember making one of these in college. they are almost stupidly easy to make and most of the components just clean up the signal noise.

  • I love your shirt! lol

  • 10:07 That happens when someone puts a patent on it ...

  • This guy is the smartest person I've ever met.

  • This is great for checking my pulse because it's hard for me to count to 6 seconds while counting how many times I've felt my pulse. It's hard enough to count to 6 as it is.

  • This is easily one of the best channels on PLtools. Edit: Also, we should be more grateful to the Phoenicians. They gave us so many wonderful things and we hardly mention them in History class.

  • Thanks for this video. I have COPD and I have an oximetre on my desk next to me, but I had no idea how it actually works.

  • 1:59 You forgot to mention the blood pressure sensors in our carotid sines and the aortic arch 👍👍👍

  • When you hold a breath, what does device shows in the next few minutes?

  • Is anyone else uncomfortable when he put his finger into it and it was lighting up different parts I got really just put off

  • "Sense-Oars" - Like Star Trek: The Motion Picture or even better, Star Trek: Lower Decks

  • My son was born with a heart defect and pulse oximeters are now part of our daily life. I've since wondered how on earth a light tells us such important information. Thank you for such a brilliant and to the point video!

  • Pretty sure my Apple Watch already does this for me lol

  • fancy blood measuring thingy: exists apple: i’ll take ur entire stock

  • After a kidney transplant I had one permanently on my finger for a couple of days. Having low haemoglobin it would often trip an alarm, usually the second I fell asleep.

  • "human ingenuity is awesome" like no shit dude what the fark do u think i'm watching this on? a cave painting? thank you so much for doing what u do, even in your past. i mean that non-sarcastic. you are literally one of my role models for whatever it is that we do. MAKE NEW VIDEOS PLEASE.

  • It is sad that in this day and age one must put so many caveats and warnings on something. Thanks for the information. And no, I will not base the remainder of my person health decisions on the knowledge I picked up from this video.

  • Can we get a video on diabetic equipment? Insulin pumps and continuous glucose monitors (CGMs) are very interesting medical tech.

  • In 1976 Hewlett Packard made the first commercially viable Ear oximeter model 47201A , it was the reference standard for many years afterwards which all others were compared against for accuracy. pubmed.ncbi.nlm.nih.gov/2322755/

  • There's a typo in the captions at 10:18: 'But learning new *thigns* and applying that knowledge is what makes us human'

  • I love how my samsung phone from 2014 had this pulse and oximeter device built into the camera. pretty neat

  • You are mostly true in "taking blood from arteria is not pleasant and vein blood is not oxigenated". U forgot one kind of blood circulation we actually use in hospitals to know about "gases" in your blood: capillar circulation. We actualli take a drop or two and get a quick analysis of it while arterial analysis is done. Less precise than arterial but more than pulsioxymeter. Jus so you know!

  • Getting arterial blood for testing isn't that difficult given the situation where it is needed frequently, a picc can be used. In my hospital experience, mine had little to no inconvenience, due to not being able to sleep on that side.

  • I have one in my Samsung galaxy note8

  • 4:53 somebody call Nickelback

  • Can you do a video on those 'light-guns' that they use to take your temperature for the Covid-19 testers?

  • Lolol. This nerd thinks blood should be on the inside

  • I was never a child. I don't have a heart. I am from Phoenix though, so you're welcome.

  • Something good to know: apparently pulse oximeters are much less accurate for Black people than white people: nyti.ms/2WEOopS

  • Hi there!