BCG Sensing Technology Brings You “Closer” to Your Heart
When you’re stuck in a traffic jam on the way to work, constantly starting and stopping, it can feel like you’re not moving forward at all. Looking ahead, all you see is a seemingly endless line of stationery traffic, as if you’re in the middle of a vast parking lot. In this kind of situation, anxiety is inevitable. Your heart rate increases, and your blood pressure rises...
Vital signs are sensitive and constantly changing. Even small emotional fluctuations can lead to a chain of changes in physiological activity. It is widely accepted that vital signs are an important metric for determining personal health, and a wide range of physiological indicators are used to provide accurate real-time insights into patients’ health.
In recent years, the concept of vital sign monitoring has gradually spread beyond medicine, giving rise to a variety of vital sign monitoring products. Vital-sign sensing devices that are in direct contact with the skin, such as photoplethysmography (PPG) bracelets and electrocardiograms (ECGs), are already in common usage. These devices require binding or sticking to the skin, which can feel restrictive, especially when monitoring sleep. Binding can even change the user's normal sleeping habits and aggravate anxiety, which is of course counterproductive to the very purpose of monitoring. In view of this, non-contact vital-sign sensing technology, typified by ballistocardiography (BCG), is emerging.
The concept for BCG was first proposed in 1877. It measures the incrementally small changes of external pressure on the surface of the human body caused by the heart beat and arterial blood flow. Essentially, it measures the mechanical effects of the heart. Its medical value was once comparable to the electrocardiograph (ECG). However, due to various factors including instability and difficulty of measurement, it gradually fell out of use in the laboratory. Since the beginning of this century, BCG technology has once again become an area of keen interest for major research institutions both in Taiwan and around the world. Given the numerous technological advancements in sensors, it has great medical potential. And, the natural synergy between BCG and IoT technology has raised expectations even further.
Everything is a health monitor
The BCG signal acquisition device consists of a sensor and a set of signal conditioning circuits. If the high-precision sensor is "hidden" in a suitable weight scale, such as a pillow, mattress, table or chair, it can monitor vital signs without skin contact and without disturbing the user's normal work or rest. With the support of BCG technology, these ordinary household staples can be transformed into high-end "life health monitors".
Science has long confirmed that the heart causes a series of periodic motions and vibrations in the human body that correspond to the heartbeat. These signals are detected through the sensor circuit and then passed through the differential preamplifier circuit, multi-stage amplifier circuit, DC blocking circuit, trap circuit, and band-pass filter circuit, before finally obtaining a usable BCG signal for analysis.
Since the BCG signal itself is very weak, it is easily distorted by noise from breathing, bodily movement and utility frequency. Consequently, the BCG signal obtained by direct measurement is often submerged in noise, and the physiological data on vital signs such as heart rate and breathing cannot be extracted. Hence it is necessary to perform noise reduction processing on the signal to restore the BCG signal characteristics and thereby identify the BCG signal.
The most widespread method for noise reduction is the Wavelet Transform (WT). In WT, the BCG signal is converted into a millivolt-level identifiable voltage signal through the processing, transformation and noise reduction process of the piezoelectric sensor and signal conditioning circuit. Finally, the processed signal is converted by the chip, completing the conversion from analog to digital. Under the description of the controller, the value of the BCG signal is conveniently presented on the display for subsequent calculation processing, analysis, and evaluation.
Based on "piezoelectric passive sensing technology", BCG sensing equipment can accurately sense the mechanical vibrations of the heart and the breathing-induced movement of the chest and abdomen of the human body, in resting or sleeping scenarios, and measure important vital signs such as heartbeat intervals and respiration rate. With the help of feature extraction and modeling technology of the heartbeat interval (HBINT) and respiratory fluctuations, BCG can also detect obstructive and central sleep apnea events even in non-contact scenarios. This gives people the power to monitor their health in real time and catch the early warning signs of diseases.
The final piece in the medical IoT puzzle
Though medical-grade monitoring products span many types of devices, large pieces of medical equipment are unsuitable in some application scenarios. This frees up sufficient development space for home-based vital-sign sensing equipment. With the support of 5G, artificial intelligence and other related technologies, we can look forward to non-contact household vital sign sensing devices becoming the "nerve terminals" of the medical IoT. They will undoubtedly both complement and improve the clinical scenarios in which monitoring products are used, enabling thousands of users to establish their own personalized health models and manage their health throughout their lives.
Professional medical terminals like BCG devices, which are both non-sensing and require minimal management, are bound to occupy an important place in the future wave of smart sensing, smart life and smart medical care. And that is heartening news indeed.
