A Novel Headset with a Transmissive PPG Sensor for Heart Rate Measurement

Abstract

-In this paper, a headset with an ear-clip type, transmissive PPG (Photo-plethysmography) sensor is presented which allows a continuous and real-time monitoring of the heart rate (HR) whilst listening to music during daily activities. Also, the proposed headset is equipped with a tri-axial accelerometer, which enables the measurement of calorie consumption and step counting. During a variety of daily activities (e.g., walking, jogging, and sleeping etc.), a PPG may be contaminated with motion artifacts. To remove these motion artifacts, we designed an adaptive filter based on the accelerometer.To evaluate the accuracy of heart rate detection, for 13 subjects the HR from the headset was compared with that detected from the ECG simultaneously recorded with a conventional ECG recorder. As a result, the error rates of the headset are 0.6%, 1.7%, 0.7%, and 5.7% over rest, walking (3km/h), jogging (6 km/h), and running (9km/h), respectively.From these results, it is likely that the proposed headset shows the performance good enough to be used in the continuous and real-time monitoring of the HR during daily activities. It is expected that the proposed headset is very efficient in the assessment of autonomic nervous activities under various physiological conditions, the exercise monitoring, and the evaluation of physical training performance.

Wearable Photoplethysmographic Sensors—Past and Present

“…In recent years, different measurement sites for PPG sensors have been explored extensively, including the ring finger [14], wrist [15,16], brachia [9,17,18], earlobe [19][20][21], external ear cartilage [22][23][24], and the superior auricular region [25][26][27]. In addition, the esophageal region has been used in clinical practice [28][29][30].…”

“…For example, an earring PPG sensor with magnetic attachment to the earlobe was developed that allowed good contact for monitoring during physical activity [22]. [20] 2008 [26] 2007 [19] 2009 [27] 2010 [22] 2012 [24] 2004 [23] 2009 [21] Sensing site Auditory Earphone/earbud PPG sensors are also available and provide greater comfort for the user. In this design, a reflective photosensor is embedded into each earbud, as shown in Figure 3.…”

“…In addition, the proposed headset is equipped with a triaxial accelerometer, which enables the measurement of calorie consumption and step-counting. However, over the course of a variety of daily activities (e.g., walking, jogging, and sleeping), the PPG sensor signal may become contaminated with motion artifacts [20].…”

Photoplethysmography Revisited: From Contact to Noncontact, From Point to Imaging

“…Several representative types of wearable PPG sensors: (a) micro-optic reflective sensor with individually tailored otoplastic housing [24]; (b) ear-hook design of reflective sensor [25]; (c) an ear clip transmissive sensor with accelerometer [26]; (d) wireless magnetic earing sensor with accelerometer [27]; (e) a golf-hat with integrated wireless reflective sensor [28]; (f) a wireless transmissive ring sensor with accelerometer [29], [30]; (g) a wireless attachable reflective sensor with receiver module [31]; and (h) Apple Watch [32]. …”

Advances in Photopletysmography Signal Analysis for Biomedical Applications

“…Regardless of the PPG sensor operating principle, it must be portable, lightweight, rugged, low cost and comfortable to use, besides keeping the signal quality under various conditions. There are several sites for measuring the PPG signal, such as the fingers and toes [ 63 , 64 , 65 ], forehead [ 66 ], wrist [ 67 ] and ear [ 62 , 68 ], since all of them have a rich arterial source and are relatively easy to attach a sensor.…”