As far as the look is concerned, the wrist-based wearable or watches that proffer heart-rate monitoring aren’t much different from their analog or mechanical counterparts. Undoubtedly, most of these gadgets have similar watch faces, wrist bands, and even the equipment such as the PPG (photoplethysmography) sensor to make the operations like heart-rate measurement possible. These sensors, which rest as an essential component within the wrist-based wearable, often fail to detect the heart-rate appropriately. Nowadays, most of the designers or manufacturers of wearable gadgets suffer from losses due to this concern. If you are also one amongst them, relax as this article has brought a precise solution to this concern. Here, you will become aware of the challenges that these modern devices can face, along with the appropriate way with which you can get rid of the same. Building the wearable with an appropriate Industrial Design is one of the best ways to keep these challenges at bay. Read below to see how.
Challenges
Amongst a lot of challenges that the PPG sensor of wrist-based wearable can face, the most common one is that while activities like jogging, the sensor even senses the changes in the blood volume related to motion take place as the wearable press and deform the blood vessels under the skin. It makes the PPG sensor to create confusions by sensing and mixing up the ratings based on the changes in blood volume and the reflected light intensity. Another factor that compels the PPG sensor to generate ambiguities in heart-rate detection is LED scattering. In the cases of repetitive arm motion due to running or jogging, badly designed wearable creates an air gap amid the photodiode and users’ skin. This air gap leads to scattering, and repetitive scattering can result in degrading the cardiac-associated PPG element from the spectrum. It ultimately turns distinguishing the required cardiac signal into a difficult task.
Measures to Resolve Challenges and Enhance Accuracy of Heart-rate Monitoring in Wrist-based Wearable
Providing wrist-based wearable with the appropriate industrial design is one of the best ways to keep them away from several challenges or glitches. The proper industrial design of your wearable will let you achieve precise heart-rate monitoring outcomes. To understand it better, go through the below example where two spectrograms – one from a poorly designed watch and other from an optimized ID have been observed. The two spectrograms are the outcomes of synchronized accelerometer signals and PPG sensor signals recorded during treadmill running and slow walking. The PPG signal relies on both the motion-related pattern and heart-rate induced pattern, and therefore, the spectrogram of an appropriately designed wrist-based wearable will show a precise spectral density of the accelerometer and PPG sensor as per the optimal industrial design. In this case, the heart-rate frequency is clearly visible, regardless of whether the user is running or walking, and thus, is easily separable from motion frequency. Nevertheless, in the case of wearable designed without focusing on proper industrial design, the spectrogram showcases either faded or invisible heart-rate. Besides, these poorly designed watches, if wore tightly, can stress the blood beds under the user’s skin. It then decreases the blood perfusion and generates difficulty in isolating heart-rate frequency and motion frequency from each other. According to the statistics obtained through this example, designing wrist-based wearable by emphasizing industrial design is imperative. It requires working on several characteristics of ID, some of which are as follows:
1. Optical distance between the photodiode and the LED light source
The distance amid the LED light source and the photodiode is a vital factor that determines signal quality and light-source intensity (battery life). If the gap is short, the photodiode will not receive reflected light from the blood. Nonetheless, if it is large, then the reflected light will turn weak and lower down the signal-to-noise ratio (SNR). Moreover, increasing the LED current blindly may overfill photodiode’s output, which then fails to provide the information required for heart-rate detection. So there is a need to maintain an appropriate (neither too less nor too much) distance between LED light source and photodiode.
2. Component’s Weight Distribution within Case
Distribution of the components’ weight is a factor essential for reducing the rocking motion of the wearable. As users often prefer watches with scratch-resistant faces, manufacturers’ preference for scratch-resistant glasses is quite high, but the existence of heavy glass on the top covering all other components of the watch exacerbates the rocking motion. Hence, both the component designer and Industrial Designer should work together to evade this top-heavy weight distribution.
Final Thoughts
As per the above information, we can conclude that precise heart-rate monitoring from wrist-worn watches depends not wholly but widely on their industrial design. That’s why it is crucial to emphasize the challenges and approaches to remove them at the ID stage itself. Hopefully, the article has provided you with most of the information that you need in this field. However, if you are still looking for additional info, feel free to contact professionals who deal with rendering services related to Industrial Product Design. For more visit: https://www.trademarkmaldives.com
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