A cloth can hear your heartbeat

Jahid Sarkera, A.K.M. Monjurul Haquea, Md. Abdullah al Rumonb
  a Lecturer, National Institute of Textile Engineering and Research (NITER)
  b 4th year Student , National Institute of Textile Engineering and Research (NITER)    
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National Institute of Textile Engineering and Research (NITER), one of the leading academic and research institutes of the country is working on different research projects in order to promote technological innovation in the textile industry. Recently a talented team has been working on developing diversified E-textile products as a part of its research activities. They have already demonstrated their products at the last 17th TEXTECH Bangladesh International Expo 2016 and acquired much appreciation from the visitors. They are trying to develop their products to the next level. Here they have shared the overview of their research work on “smart cloth” that can measure heart rate and show it in real time graphical view. In June 2017 issue another article was published from one of the authors of NITER on Shape Memory Materials.

Abstract:

Technical Textile is becoming a roaring field nowadays. Fiber, yarn, fabrics and other structures with functional and technical properties engaged as an alternative material with a limitless range of applications. Generally the word “smart material” that refers those that can sense and response in a controlled and predicted manner to environment stimuli that may got from mechanical, chemical, thermal, magnetic or other form. Photo plethysmography principle was applied in this experiment. A Nano rigid sensor combined with ordinary woven fabric and then signal was analyzed to get a cumulative and observable sketch.

Keywords: Electronic textiles, smart fabrics, smart clothes, wearable computing, interactive textiles, Heart rate sensible cloth

Introduction:

Wearable technology is all the buzz in the tech world at the moment. Wearable electronics are currently making the deepest run into the mass market, but there’s a nascent and potentially greater development underway of smart fabrics. Market research firm ABI estimates that 61 percent of wearable technologies are sports/health activity trackers the market will grow by 50 percent during the course of this year.

Flexible sensors have made a new phase of “smart Textile” where its smartness is not derived from inherent responsive materials such as SMP (shape memory polymer), PCM (phase change material), or Chromatic materials rather Nano-rigid sensors are incorporated in the garment structure.

Here the pulse sensor is working with Nano IR sensor that is incorporated with ordinary textile using flexible sewed circuit that can able to give a continuous signal and an actuator is processing with a certain logic. Results are shown in graphical and numerical view that also can be shown by mobile app.

Material and Method:

A person’s heartbeat is the sound of the valves in his/her’s heart due to the expansion and contraction of blood vessel when blood enters and leaves it. The number of times the heart beats per minute (BPM), is the heart beat rate and the beat of the heart that can be felt in any artery that lies close to the skin is the pulse. Generally people measure their heart rate manually. By holding their hands they feel the pulse in the nerve and look at their watch to count the heart beats per minute. Our heart does this around 70 to 84 times a minute for a healthy person.

Sensor integrated in Textile

Figure 01. Sensor integrated in Textile

Smart cloth that can measure heart beat rate functioned with a tiny rigid sensor and flexible conductive yarn that can measure and transmit information about the wearer in real time. The sensor is based on the principle of photo plethysmography(PPG). It measures the change in volume of blood through any organ of the body which causes a change in the light intensity through that organ (a vascular region). This change is very small but we can measure it with the help of microcontroller.

There are two types of photo-plethysmography (PPG).

Transmission: Light emitted from the light emitting device is transmitted through any vascular region of the body like earlobe and received by the detector.

Reflection: Light emitted from the light emitting device is reflected by the regions.

High absorption

The sensor consists of a light emitting diode in the centre which helps in detecting the heartbeat. Below the diode, there is a noise elimination circuitry which is supposed to keep away the noise from affecting the readings. When a heartbeat occurs, blood is pumped through the human body and gets squeezed into the capillary tissues. But in between two consecutive heartbeats this volume inside capillary tissues decreases. When a tissue is illuminated by the light source then it either reflects (a finger tissue) or transmits the light (earlobe). Some of the light is absorbed by the blood and the transmitted or the reflected light is received by the light detector. The amount of light absorbed depends on the blood volume in that tissue.

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Figure 03. Typical response of sensor to amount of blood in vain

Result and discussion:

The variation in light transmission and reflection create resistance and voltage difference that can be used as a pulse from the output of pulse sensor. This pulse can be then conditioned to measure heartbeat and then programmed accordingly to read as heartbeat count. The result then can be displayed as graphical view that gives some extra feature on condition.

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Figure 04. Graphical view of beats and rate of pulse

The user can get this data through smart devices and also a doctor can monitor various patients’ data simultaneously through wireless transformation. The graphical view demonstrates the fluent and abnormal behaviour of pulse wave that needs critical reasoning.

Conclusion:

This development is extraordinary and a continuous process which demands more accurate sensibility of sensors. Sensors will continue to be miniaturized until they reach micrometre and even nanometre scale. They will then be able to be deeply integrated into material fibres. Another fact of progress is the energy sector. These sensors need to be self-sufficient. There are currently three approaches being explored, recovering mechanical energy (from the body’s movements), recovering heat from the body, and generating solar power. It’s impossible to determine a list of potential uses for upcoming technology at the moment because the possibilities are endless.

Reference:

  1. Matteo Stoppa and Alessandro Chiolerio, 2014, Wearable Electronics and Smart Textiles: A Critical Review, 10.3390/s140711957: 11958-11983.
  2. Langereis, R.; Bouwstra,  S.;  Chen,  W.  Sensors, Actuators and Computing Architecture Systems for Smart Textiles. In Smart Textiles for Protection; Chapman, R., Ed.; Woodhead Publishing: Cambridge, UK, 2012; Volume 1, pp. 188–207.
  3. Custodio, V.Herrera , F.J. Lopez , G.Moreno, A review on architectures and communications technologies for wearable health-monitoring systems. Sensors 2012, 12, 13907–13946.
  4. Minyoung Suh, Kate Carroll, and Nancy Cassill, 2010, JTATM Volume 6, Issue 4. 1-16.
  5. Textile Institute (2006b). Clothing Biosensory Engineering (Li, Y. and Wong, A. Ed.). Florida: CRC Press.
  6. Tarun Agarwal, Heartbeat Sensor-Working and Application
  7. Lam Po Tang G. K. Stylios, 2005 , An overview of smart technologies for clothing design and engineering, IJCST, Vol. 18 Iss 2 pp. 108 – 128

ProsantaGope and Tzonelih Hwang, “BSN-Care: A Secure IoT-Based Modern Healthcare System Using Body Sensor Network”,IEEE SENSORS JOURNAL, VOL. 16, NO. 5, MARCH 1, 2016.

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