Recently, several well-known brands of smartwatches and fitness bands, including Apple,
have monitored blood oxygen saturation and heart rate data for items such as sausages, instant coffee boxes,
fruits, vegetables, and more
, sparking heated discussions among netizens
What is going on here?
Apple Watch Measures Radish Heart Rate Official Customer Service: The Device May Be Very Sensitive
“This is an Apple Watch, testing the heart rate of a radish, it was 79 BPM a minute ago.” On the 4th, a netizen from Dalian, Liaoning, named “Old Light Off” posted this video. In the video, there is a radish on the table, and the watch is placed in the middle section as if worn on a human wrist,the netizen clicked on the “heart rate” option on the watch interface, and the screen immediately displayed “Measuring”, and below it showed “79 BPM (1 minute ago)”, and after a few seconds, the test result showed, a heart rate of 68 BPM, which then changed to 60 BPM.
△ The Apple Watch measured the radish’s “heart rate”. Image source: Shangyou News
The video has attracted attention and heated discussions. Some netizens questioned whether this watch is genuine. Others expressed amazement at the technology, saying it can measure heart rates even when placed on a radish. Some netizens reported measuring a tissue and getting a heart rate of 80 BPM. However, most netizens want to know what the principle behind this is.
According to Shangyou News, Apple customer service responded to reporters, stating that it may be that the electronic device is very sensitive, misinterpreting signals as human signals, thus producing results, but this does not affect the accuracy of measurements for human indicators.
On January 5, the netizen who posted the video was interviewed by reporters. He stated that his Apple Watch is an Apple Watch Series 6, purchased in September 2021 through Apple’s official retail channel, and provided reporters with relevant purchase receipts, which showed that the watch was purchased for 3399 yuan.
In response, Apple customer service told reporters that if users encounter similar situations, they can contact the official support for hardware diagnostics. First, pair the watch with the corresponding phone, go to settings, find “Privacy and Security”, and after the official sends the relevant diagnostic program, a pop-up will appear. Then, in “Analysis and Improvement”, select “Start using Apple Support” to conduct diagnostics, which can be completed in 1-2 minutes to preliminarily diagnose whether there are hardware issues with the watch’s sensors. Additionally, if problems arise, users can contact the official support to develop a tailored solution.
The customer service representative further stated that, according to their understanding, some smartwatches or fitness bands on the market, including Apple-related smartwatches, have also measured blood oxygen or heart rates on dolls, fruits, and other items, which may be due to the electronic devices being very sensitive, misinterpreting signals as human signals, thus producing results, but this does not affect the accuracy of measurements for human indicators when the watch is worn normally.
Relevant technical personnel told Shangyou News that it may be due to the high sensitivity of the electronic device’s sensors, but only Apple’s technical staff would know the product’s detection technology logic best.
According to Chengshi Interactive, a netizen posted a short video showing a certain domestic brand smartwatch worn around a teddy bear’s neck, measuring the bear’s “blood oxygen” at 99% and “heart rate” at 84 BPM. Mr. Gu from Hangzhou used this brand’s smart band to measure the blood oxygen of a pomelo, which showed a blood oxygen level of 86%. His friend also used this brand’s smartwatch to measure a banana’s “blood oxygen” at 96% and “heart rate” at 87 BPM.
Meanwhile, a netizen from Beijing posted a Douyin short video showing that he placed an Apple Watch on an orange, and the watch displayed the orange’s “heart rate” as 94 BPM.
Can Huawei Watch Measure Sausage Heart Rate? Official Response
Coincidentally, a video also appeared on video platforms showing a Huawei watch and an Apple watch placed on a sausage, and the Huawei watch surprisingly measured heart rate and blood oxygen.
Not only sausages, many netizens reported that the Huawei watch can also measure blood oxygen and heart rate on milk cartons, which has sparked controversy.
In response, on December 29, Huawei’s consumer service hotline staff stated that Huawei’s smart wearable devices rely on optical sensors to measure blood oxygen by detecting fluctuations in light signals, and placing the watch on paper boxes, fruits, or towels may very rarely misinterpret signals as human signals, resulting in blood oxygen values.
The official added that Huawei will continue to optimize algorithms to improve accuracy regarding this issue.
It is understood that blood oxygen saturation refers to the concentration of oxygen in the blood. Low blood oxygen levels can lead to fatigue, drowsiness, decreased memory, and long-term insufficient blood oxygen levels can harm organs such as the brain and heart.
Huawei watches utilize TruSeenTM4.5+ heart rate monitoring technology to intelligently monitor blood oxygen saturation. However, Huawei also reminds users that this product is not a medical device, and the monitoring data and results are for reference only and should not be used for diagnostic or medical purposes.
Why Can Smartwatches Measure Blood Oxygen and Heart Rate of Fruits and Other Objects?
According to Chengshi Interactive, reporters consulted customer service from a well-known domestic brand’s JD flagship store. The representative stated that the principle of smartwatches measuring blood oxygen is based on the different light absorption rates of oxygenated hemoglobin and deoxygenated hemoglobin in the blood. The wearable device emits light, and based on the characteristics of the reflected light received, combined with algorithms, it accurately measures blood oxygen levels.
“When the sensor side of the wearable device is placed facing down (such as on a table, sink, sofa, or blanket), if the light received by the device is similar to the reflected light from the skin, it may misinterpret it as a human signal, thus calculating blood oxygen values.”
The customer service further explained that this phenomenon does not affect the accuracy of blood oxygen detection when the device is worn correctly.
Regarding the phenomenon of the Apple Watch detecting non-living heartbeats, reporters also consulted customer service from Apple’s JD flagship store. The representative stated that heart rate and blood oxygen are calculated through reflected light, “paper can also be used to measure these values with the watch, which is a normal phenomenon.”
As for whether the Apple Watch can guarantee the accuracy of measuring human blood oxygen and heart rate, the representative said “it cannot guarantee” and does not recommend medical use.
Digital blogger @Navis Li provided an explanation: “The principle of blood oxygen detection is based on the inconsistent absorption ratios of hemoglobin at different wavelengths of red light. Essentially, the device has red light LEDs and infrared light LEDs for illumination, with different wavelengths. Then, by sensing the reflection differences of different wavelengths through sensors, it can calculate blood oxygen levels. This principle is very mature and relatively accurate. In this case, if we choose an object that can reflect both wavelengths, the device will naturally calculate the blood oxygen saturation data according to the model.”
△ Image source: Network screenshot
In addition, digital blogger @Wu Shifu also provided a similar response: Currently, the principle of blood oxygen detection in wearable devices is based on the amount of hemoglobin absorption of red and infrared light in skin blood vessels to indirectly calculate blood oxygen levels. However, under certain conditions, some objects’ optical signals may present similarities to human skin blood vessels, leading to a small probability of misinterpretation as human information, thus resulting in the calculation of these objects’ blood oxygen levels, which does not affect the accuracy of the data detected when the device is used normally.
In summary: When you wear it on your wrist, the measured value is the blood oxygen level; whereas when you measure it with a sausage on top, it measures the difference in infrared and red light received and reflected by the sausage.
According to Shangyou News, reporters interviewed experts in the relevant field, who provided related advice: as long as devices like watches and bands are worn correctly on the wrist, the measured blood oxygen values are referenceable. Any device must be used correctly according to the instructions; otherwise, the data obtained will have no reference value. For example, using a fingertip blood oxygen meter to measure a sausage or banana will also yield corresponding blood oxygen readings, but because the method of use is incorrect, it has no reference significance.
Are Mobile Apps/WeChat Mini Programs Reliable for Measuring Blood Oxygen?
According to Chengshi Interactive, many people have also discovered that mobile apps/WeChat mini programs can measure blood oxygen and heart rate for free.
Mr. Gu measured his blood oxygen using a WeChat mini program called ABC Health. “Just place your index finger lightly on the camera and flash for 90 seconds to receive the report data, which is the same as the results from the smart band measurement.”
How accurate are the blood oxygen saturation values measured by mobile apps/mini programs?
Professor Sha Xianzheng, head of the Biomedical Engineering program at China Medical University, stated in a media interview that mobile apps only serve as a monitoring and reference tool, and their measurement accuracy is certainly not as good as that of medical-grade blood oxygen monitors.
Professor Sha explained that, in simple terms, blood oxygen saturation refers to the concentration of oxygen in the blood, which is an important physiological parameter of respiratory circulation.
The principle of fingertip blood oxygen saturation monitors is to utilize the different absorption rates of hemoglobin and oxygenated hemoglobin at different electromagnetic wave wavelengths to measure the absorption rates of two different wavelength lights, calculate the ratio of oxygenated hemoglobin to hemoglobin, and define blood oxygen saturation based on that ratio. Fingertip blood oxygen monitors typically use projection light, while electronic bands mostly use reflection light.Fingertip blood oxygen monitors or bands are quite mature products, and their measurement results are relatively accurate.
Source: Dongfang Net, Shangyou News, Chengshi Interactive, Daily Economic News, etc.
Video: Zhang Li
Editor: Ivy
Reviewer: Qian Chengcan