Detection of multi-biosignal using a quartz crystal resonator based wide range load sensor with compact frequency counter

Monitoring of biosignals plays important roles in health management in daily life. Especially, the sensing method of biosignals, which does not require special efforts such as restraining people or wearing the sensors to measure them, is really important to maintain monitoring activities of people. We call such method what a sensing way should be for monitoring of biosignals as casual sensing methods. Previously, we have developed highly sensitive and wide-measurement-range load sensors based on measuring frequency shift of quartz crystal resonator (QCR) as the sensing principal. We have integrated the load sensor into a chair, and measure the load when people just sit on it. Since the load sensor has wide measurement range of 105 order, multi-biosignal; heartbeat, respiration, and body motion under the weight-loaded environment can be measured from load information. Thus, people can casually monitor the biosignals by sitting on the chair. However, the previous sensing system required us to measure the frequency shift of one-Hz order in tens-MHz of the resonant frequency of a QCR. In this case, the sensing system requires a expensive frequency counter, and it is not suitable for daily use situation such as in-home sensing. In this paper, we presents the detection of multi-biosignal method using a newly developed load sensing system which utilizes the developed frequency counter unit. In order to measure the frequency shift of one-Hz order in tens-MHz of the resonant frequency, we use a differential method of signal for two QCRs with an electrical signal-mixing circuit. By using the method, we can reduce the required measurement range for frequency from tens-MHz to tens-kHz. The load sensing performances were evaluated, and the results showed that the sensitivity and withstand load were 2.9 [mN] and 300 [N], respectively. Finally, we demonstrated the measurement of multi-biosignal by using constructed system, and succeeded in detecting respiration, heartbeat, and body motion.

[1]  Fumihito Arai,et al.  Miniaturization of wide-range QCR load sensor for biosignal sensing , 2015, 2015 International Symposium on Micro-NanoMechatronics and Human Science (MHS).

[2]  R. Mccraty,et al.  The effects of emotions on short-term power spectrum analysis of heart rate variability . , 1995, The American journal of cardiology.

[3]  J. Lekkala,et al.  Measurement of heart sounds with EMFi transducer , 2007, 2007 29th Annual International Conference of the IEEE Engineering in Medicine and Biology Society.

[4]  Jim Euchner.  Design , 2014, Catalysis from A to Z.

[5]  Alpo Värri,et al.  The potential of EMFi sensors in heart activity monitoring , 2004 .

[6]  Kiyoko Yokoyama,et al.  Optimum arousal level preservation system using biosignals. , 2011, Journal of human ergology.

[7]  Shigeki Sugano,et al.  A novel tri-axial capacitive-type skin sensor , 2015, Adv. Robotics.

[8]  Fumihito Arai,et al.  Wide Range Load Sensor Using Quartz Crystal Resonator for Detection of Biological Signals , 2015, IEEE Sensors Journal.

[9]  Fumihito Arai,et al.  Miniaturized load sensor using quartz crystal resonator constructed through microfabrication and bonding , 2014 .

[10]  A. Akhbardeh,et al.  An EMFi-film sensor based ballistocardiographic chair: performance and cycle extraction method , 2005, IEEE Workshop on Signal Processing Systems Design and Implementation, 2005..

[11]  J. Ratajski,et al.  Force-frequency coefficient of singly rotated vibrating quartz crystals , 1968 .

[12]  Zheyao Wang,et al.  A thickness-shear quartz resonator force sensor with dual-mode temperature compensation , 2003 .

[13]  Jouko Siivola,et al.  Non-invasive piezoelectric transducer for recording of at the level of diaphragm , 1998 .

[14]  Changhyun Pang,et al.  Recent advances in flexible sensors for wearable and implantable devices , 2013 .

[15]  E.P. EerNisse,et al.  Review of thickness-shear mode quartz resonator sensors for temperature and pressure , 2001, IEEE Sensors Journal.

[16]  J Siivola,et al.  Non-invasive piezoelectric transducer for recording of respiration at the level of diaphragm. , 1998, Electroencephalography and clinical neurophysiology.

[17]  Fumihito Arai,et al.  Compact Force Sensor Using AT-Cut Quartz Crystal Resonator Supported by Novel Retention Mechanism , 2009, J. Robotics Mechatronics.

[18]  M. Uomoto,et al.  Atomic diffusion bonding of wafers with thin nanocrystalline metal films , 2010 .

[19]  Fumihito Arai,et al.  Design, fabrication and characterization of compact force sensor using AT-cut quartz crystal resonators , 2008, 2008 IEEE/RSJ International Conference on Intelligent Robots and Systems.

[20]  K. Watanabe,et al.  Noninvasive Bed Sensing of Human Biosignals Via Piezoceramic Devices Sandwiched Between the Floor and Bed , 2012, IEEE Sensors Journal.

[21]  Fumihito Arai,et al.  Microfabrication of wide-measurement-range load sensor using quartz crystal resonator , 2015, 2015 28th IEEE International Conference on Micro Electro Mechanical Systems (MEMS).

[22]  Carlos Ramirez,et al.  Non-Invasive Technology on a Classroom Chair for Detection of Emotions Used for the Personalization of Learning Resources , 2010 .