1 00:00:00,000 --> 00:00:08,000 Like the thirsty cast members of The Bachelorette, Samsung Aura and, if 2 00:00:05,480 --> 00:00:13,000 rumors are correct, [music] Apple all want to put a ring on it. And why not? 3 00:00:11,400 --> 00:00:18,920 The promise of a smart ring is undeniably sexy. A screen-free titanium 4 00:00:16,240 --> 00:00:24,080 hoop that tracks your vitals 24/7. Who wouldn't want it? But, like a reality TV 5 00:00:21,720 --> 00:00:28,720 marriage, buying a smart ring is sometimes followed by regret. If you've 6 00:00:26,640 --> 00:00:32,160 ever wondered why your smart ring thinks you were napping while you were working 7 00:00:30,320 --> 00:00:36,520 and yet misses your PR at the gym, that's because, turns out, shrinking an 8 00:00:34,560 --> 00:00:40,760 entire lab's worth of equipment down to the size of a piece of jewelry requires 9 00:00:38,480 --> 00:00:45,000 some serious engineering compromises. Compromises that could be fat-fingering 10 00:00:43,000 --> 00:00:48,560 your biometric data. Let's break these devices down, starting with the main 11 00:00:46,880 --> 00:00:53,360 sensor. [music] PPG, or photoplethysmography, is a fancy name 12 00:00:50,800 --> 00:00:57,320 for shining light into your skin and measuring how much bounces back. In a 13 00:00:55,320 --> 00:01:01,800 hospital, they'll clip a sensor onto your fingertip, yield transmissive PPG. 14 00:01:00,080 --> 00:01:06,600 It's incredibly accurate because the signal is unobstructed. Smartwatches, on 15 00:01:04,160 --> 00:01:10,840 the other hand, use reflective PPG, where the sensor and the photodiode are 16 00:01:08,440 --> 00:01:14,800 on the same side. Fun fact, by the way, they use green light because your blood 17 00:01:12,840 --> 00:01:20,000 absorbs it like a sponge, providing a high-contrast signal. Depending on, you 18 00:01:17,320 --> 00:01:23,200 know, how far apart your photodiode is, if it's, say, on the curvature of a 19 00:01:21,400 --> 00:01:27,920 ring, you may actually kind of be between these modalities, where you're 20 00:01:25,000 --> 00:01:31,240 somewhat like in a transflective approach. You may see behavior of both 21 00:01:29,760 --> 00:01:36,200 like a reflective and a transmissive PPG. Smart rings can occupy a weird 22 00:01:33,800 --> 00:01:39,440 middle ground. Because the sensors wrap around your finger, light travels 23 00:01:37,800 --> 00:01:44,680 further through your skin than it would from a smart watch. This gives the ring 24 00:01:41,560 --> 00:01:46,880 a slight signal advantage, but it's one 25 00:01:44,680 --> 00:01:49,440 that unfortunately gets dragged down by the constraints that arise from its size 26 00:01:49,386 --> 00:01:55,480 >> [music] >> and from its battery. >> The amount of light you need in order to 27 00:01:53,440 --> 00:01:58,400 measure an appreciable pulse is proportional also to the active area of 28 00:01:57,200 --> 00:02:02,720 the photodiode that you're using to sense it with. So, a bigger photodiode, 29 00:02:00,480 --> 00:02:07,440 a bigger sensor, means you can use less light, less current, in order to perform 30 00:02:05,280 --> 00:02:11,480 the same relative measurement. If you only just shrink the photodiode itself, 31 00:02:09,960 --> 00:02:15,120 you're going to be decreasing your your signal-to-noise ratio 32 00:02:13,360 --> 00:02:18,240 and have to, you know, boost your LED light in order to accommodate for that. 33 00:02:17,040 --> 00:02:22,320 You can think of it kind of like listening to a conversation in a crowded 34 00:02:20,040 --> 00:02:25,360 bar. A smartwatch stands next to a person with a large, directional 35 00:02:23,800 --> 00:02:28,720 microphone. A smart ring, on the other hand, is trying to hear them from across 36 00:02:27,320 --> 00:02:32,520 the room using a tiny little spy mic taped to their collar, 37 00:02:31,040 --> 00:02:37,856 which brings us to the battery. The Samsung Galaxy Watch Ultra packs 590 38 00:02:36,520 --> 00:02:43,840 mA hours. >> [music] >> The Galaxy Ring, 39 00:02:39,760 --> 00:02:46,720 17 to 22 and 1/2. And yet, the ring 40 00:02:43,840 --> 00:02:50,880 claims it lasts for up to 7 days. How? Well, 41 00:02:48,840 --> 00:02:54,120 because it doesn't. Both devices use duty cycling to extend their usable 42 00:02:52,600 --> 00:02:57,960 charge time, but because the watch has a larger battery, one intense session 43 00:02:56,160 --> 00:03:02,600 isn't going to drain it. The ring, on the other hand, has about 44 00:02:59,440 --> 00:03:04,320 the battery of a Cheerio. [music] 45 00:03:02,600 --> 00:03:07,200 They have also large dormant periods, where the ring simply is not measuring 46 00:03:06,120 --> 00:03:11,262 at all. And and so you can kind of think of it as like interlacing on top of 47 00:03:09,760 --> 00:03:15,520 interlacing, you know, in order to [music] make it so maybe you only measure the pulsations, measure the 48 00:03:13,960 --> 00:03:19,520 heart rate, pulse ox, you know, for a minute, you know, every 10, 15, 20 49 00:03:18,040 --> 00:03:23,760 minutes, for example, in order to to keep conserving uh power. [music] To put 50 00:03:21,760 --> 00:03:28,160 this in perspective, when the Franklin Research Lab built their own DIY smart 51 00:03:25,920 --> 00:03:32,960 ring, the battery gave out after about 4 to 6 hours of continuous use. So, if we 52 00:03:30,720 --> 00:03:37,960 take that as a baseline for true continuous tracking, to survive a full 53 00:03:35,320 --> 00:03:42,880 168-hour week of nonstop data collection, you'd need to wear 34 rings 54 00:03:40,480 --> 00:03:46,800 and swap them out like ammunition magazines. By Wednesday, you'd look more 55 00:03:44,960 --> 00:03:49,320 like the Divination instructor at Hogwarts than like a fitness enthusiast. 56 00:03:49,252 --> 00:03:54,492 >> [music] >> The reason that smart ring bands can claim a week while Dr. Franklin gets 57 00:03:53,400 --> 00:03:59,560 only 5 hours >> [music] >> is the sampling rate. When a researcher 58 00:03:56,880 --> 00:04:04,320 says continuous, they usually mean high-frequency sampling. When a consumer 59 00:04:01,800 --> 00:04:08,640 wearable says continuous, they often mean, "Ah, we check in every now and 60 00:04:06,720 --> 00:04:13,360 then, and then we interpolate a bit so the graph looks like a solid line." And 61 00:04:11,200 --> 00:04:16,560 if you have a darker skin tone, the LEDs actually have to work harder to get a 62 00:04:14,840 --> 00:04:19,320 readable signal, which can cut that already slim battery life nearly in 63 00:04:18,720 --> 00:04:25,240 half. [music] Now, that isn't to say that the form factor has no benefits. There is a 64 00:04:23,000 --> 00:04:28,680 reason that hospitals clip sensors onto your fingers. They are densely packed 65 00:04:27,160 --> 00:04:32,240 with arteries that are right close to the surface of the skin. But for smart 66 00:04:30,520 --> 00:04:36,520 rings, that's kind of a double-edged sword. Besides being so darn cute and, 67 00:04:34,448 --> 00:04:40,400 [music] you know, fingery, fingers are your body's temperature control meat 68 00:04:38,200 --> 00:04:44,680 sticks. When you have vasoconstriction or dilation 69 00:04:42,520 --> 00:04:48,800 uh due to being cold or due to, say, being in a sauna, that will, again, 70 00:04:47,040 --> 00:04:52,400 change the distribution of blood within the skin and impact your 71 00:04:50,200 --> 00:04:56,200 photoplethysmography signal. Typically, vasoconstriction 72 00:04:54,040 --> 00:04:59,280 or having that blood redistributed away from the surface of 73 00:04:57,760 --> 00:05:03,360 the skin can have a detrimental effect on the PPG. So, it'll decrease your 74 00:05:01,560 --> 00:05:06,680 pulses, it will decrease your signal-to-noise ratio, and then the 75 00:05:05,120 --> 00:05:11,480 opposite is true when you have perfusion. Cold hands equals a weaker 76 00:05:09,480 --> 00:05:15,440 signal, which equals your ring struggling to find your pulse. Lock 77 00:05:13,280 --> 00:05:19,840 outside in the winter or sit next to an aggressive air conditioner, and your 78 00:05:16,960 --> 00:05:25,400 ring huh might think you're a spooky vampire with no pulse. Or Sam Altman. 79 00:05:22,600 --> 00:05:28,360 Unlike the finger, the wrist sits closer to the body's core, [music] staying 80 00:05:26,560 --> 00:05:32,400 warmer and maintaining more consistent blood flow, giving the watch a natural 81 00:05:30,320 --> 00:05:35,320 edge in colder environments. But hey, I mean, if sitting still in a freezing 82 00:05:33,600 --> 00:05:39,880 room isn't your only hobby, what about if you actually exercise? 83 00:05:37,760 --> 00:05:43,760 Even a simple jog is going to slosh your blood around enough to give the sensors 84 00:05:41,480 --> 00:05:48,040 a headache. But for hand heavy lifting, the ring becomes basically decorative. 85 00:05:46,280 --> 00:05:53,440 See, the problem isn't just motion, it's grip. Odoo, your business doesn't need 86 00:05:51,240 --> 00:05:57,720 different apps for signing agreements, running a POS, doing inventory 87 00:05:55,440 --> 00:06:01,720 management, or running email marketing. All you need is Odoo. It's a business 88 00:06:00,040 --> 00:06:05,720 management software with just about anything you could imagine needing 89 00:06:03,160 --> 00:06:10,160 integrated into a single platform. It's customizable and built to be easy to 90 00:06:07,880 --> 00:06:15,920 navigate since you pick and choose only what you need, no extra fluff. And if 91 00:06:13,320 --> 00:06:20,600 you only need one app, it's free. Use our link for a free 15-day trial with no 92 00:06:18,800 --> 00:06:24,320 credit card required. When someone tightly grips a steering 93 00:06:22,440 --> 00:06:27,800 wheel or a barbell, we typically call this motion artifacts. At the uppermost 94 00:06:26,280 --> 00:06:32,000 level of your skin, you have a capillary bed, and when you apply pressure to this, that's the first layer that 95 00:06:30,520 --> 00:06:36,680 actually gets compressed. And so you end up with a a large spike in your photoplethysmography signal. That's not 96 00:06:35,120 --> 00:06:41,680 attributed to your pulsations or your heart rate, which is the thing we want to measure. These motion artifacts and 97 00:06:40,000 --> 00:06:45,960 pressure-induced [music] signal loss hit simultaneously, and they compound fast. 98 00:06:43,840 --> 00:06:48,920 White-knuckling a barbell squeezes blood out of the very capillaries the ring is 99 00:06:47,320 --> 00:06:52,680 trying to read. So, by the time your heart rate has climbed to 160 beats per 100 00:06:51,280 --> 00:06:56,080 minute mid-set, the ring might be reporting a breezy 80. A quick 101 00:06:54,440 --> 00:07:00,240 TechQuickie safety tip, by the way, wearing a metal ring during heavy lifts 102 00:06:57,880 --> 00:07:03,760 is not a good idea. Beyond scratching the finish of your ring, you're actually 103 00:07:01,760 --> 00:07:07,160 risking a degloving accident. Seriously though, do not Google that. The standard 104 00:07:05,360 --> 00:07:11,720 way to deal with motion artifacts is to cross-reference the accelerometer data. 105 00:07:09,560 --> 00:07:16,600 If motion exceeds a specific threshold, then the PPG data just gets discarded 106 00:07:13,640 --> 00:07:22,000 entirely because a gap is better than a wrong number. A 2024 study even found 107 00:07:19,000 --> 00:07:23,920 that you might need to discard up to 70% 108 00:07:22,000 --> 00:07:28,160 of heart rate variability readings due to poor signal quality. To combat this 109 00:07:26,160 --> 00:07:33,320 data trashing, researchers are working on transformer-based AI models to 110 00:07:30,480 --> 00:07:37,360 reconstruct corrupted PPG signals. So, the sensor's tiny, the battery prevents 111 00:07:35,440 --> 00:07:41,120 continuous tracking, cold hands kill the signal, gripping blinds it, and most of 112 00:07:39,520 --> 00:07:46,040 these rings aren't even FDA-regulated medical devices, making them pretty much 113 00:07:43,120 --> 00:07:49,320 high-end accessories with an asterisk. So, are they an overpriced piece of 114 00:07:48,040 --> 00:07:53,160 e-waste? Actually, no. There is one time of day 115 00:07:51,680 --> 00:07:57,800 where almost all of these problems disappear, >> [music] >> and that's during sleep. Unless you're 116 00:07:56,080 --> 00:08:01,240 David Goggins, you're probably aren't gripping a barbell in your sleep, so 117 00:07:59,400 --> 00:08:06,440 your hands are relaxed and your arteries are right at the surface. Smart rings 118 00:08:03,400 --> 00:08:07,880 can get incredibly accurate resting data 119 00:08:06,440 --> 00:08:13,800 while being far more comfortable to sleep in than this darn thing. Aura even 120 00:08:11,120 --> 00:08:17,960 boasts about their .999 correlation with medical-grade ECGs for 121 00:08:16,000 --> 00:08:22,560 resting heart rate, which checks out. Even with a few misbeats, basic average 122 00:08:20,080 --> 00:08:25,760 is easy. Their .984 HRV correlation claim, however, has a massive catch. 123 00:08:24,400 --> 00:08:31,520 Heart rate variability measures millisecond differences between individual beats, and it needs [music] 124 00:08:29,360 --> 00:08:35,000 beat-to-beat continuity. So, a gap in the data doesn't just reduce accuracy, 125 00:08:33,440 --> 00:08:38,719 it invalidates the entire measurement window, which is why smart rings filter 126 00:08:37,000 --> 00:08:43,320 out low-confidence data before reporting. To legally be able to claim 127 00:08:40,919 --> 00:08:48,400 this HRV accuracy, many validation studies use sedentary participants. In 128 00:08:45,960 --> 00:08:51,200 one, no subject's heart rate broke 90 beats [music] per minute, so it's kind 129 00:08:49,640 --> 00:08:55,720 of easy to be accurate when your user's just vibing on the couch. As for the 130 00:08:53,760 --> 00:09:00,000 high-level scores, like sleep score, readiness, and stress, those are 131 00:08:57,680 --> 00:09:04,400 proprietary algorithms that arguably don't mean much. It's kind of a way of 132 00:09:02,280 --> 00:09:08,840 gamifying your sleep to see who [music] can have the most readiness, I suppose, 133 00:09:07,200 --> 00:09:13,000 and to help you justify your $5.99 monthly subscription for the rest of your life. If you want to see the 134 00:09:11,240 --> 00:09:16,400 testing facilities that smart wearables, like rings, are designed in, check out 135 00:09:14,720 --> 00:09:21,400 this video where I visited one in China. It's actually, for all of the dunking on these devices 136 00:09:19,480 --> 00:09:24,840 that we just did, a lot more elaborate and way cooler than you might think.