REMOTE HEALTH MONITORING SYSTEM USING PIC MICROCONTROLLER

Transcription

1 REMOTE HEALTH MONITORING SYSTEM USING PIC MICROCONTROLLER S.Sakuntala #1 and R.Ramya Dharshini *2 # B.E, ECE, Mepco Schlenk Engineering College, Sivakasi,India * B.E, ECE, Mepco Schlenk Engineering College, Sivakasi,India Abstract In this paper, the technology advances on sensors, connected to human body enables the design of health monitoring system. The system was developed to monitor the vital signs such as body temperature, ph level, Heart beat rate, Oxygen saturation level and ECG. Index Terms Biomedical sensors, Hyperterminal software, PIC microcontroller, Zigbee. PIC is an electronic circuit that can be programmed to carry out various tasks.pic Microcontrollers are produced by Microchip technology. It is a very powerful device that includes many built in modules such as EEPROM, 2 Timers, 10 bit ADC, Comparators and UART. The most important features of PIC microcontroller is that, it can be re-programmed as they use flash memory. In this paper, PIC16F877A is used which is available in 40/44 pin packages has 5 I/O ports namely PORTS A,B,C, D and E. I. INTRODUCTION Health monitoring systems become a hot topic and important research field today. Now-a-days the maximum new research is emphasizing on improving the quality and healthy life by designing and fabricating sensors which are either in direct contact with the human body (invasive) or indirectly (non-invasive). The main reason behind this development is rapid increasing of population worldwide. The monitoring system allows an individual to closely monitor their changes in vital signs and also provide feedback which helps to maintain an optimal health status. The device is designed to integrate into a telemedical system, as it can even alert medical personnel providing life-threatening changes to occur. ZigBee wireless module is used to sense the remote patient data. Wireless sensors and sensor networks drag more attention to the research community because of its wide applications such as scalability, power management and flexibility of architecture. All sensor data from the parameters which are in the direct contact with body parts such as Heart beat rate, Oxygen saturation level, body temperature, ph level, and ECG are transferred by using a group of ZigBee wireless module. The system adopted the wireless sensor ZigBee for using as a real-time health monitoring system on a patient. Fig. 1 Pic Architecture II. HEALTH MONITORING SYSTEM USING PIC Bio-Medical Sensor Network have the ability to diminish the workload of medical care. The introduction of Personal Area Network greatly simplifies the collection of physiological data. The patients can be engaged in their day to day life activities while being monitored. The physician can have the surveillance of patient s health condition for 24 hours using this system. Using PIC(Programmable Interface Controller), it provides a low cost health monitoring system. The PIC at the transmitter obtains the analog input from the Sensors, does the signal analysis and converts the analyzed output into digital data. The digital data is sent serially through TX pin to the ZigBee module[2]. At the receiver, the ZigBee receives the sent data and serially transmits it to a PC using RS232. The received data is displayed in the PC using Hyperterminal software. The fig. 2 depicts the block diagram of health monitoring system. 209

2 B. Heart Beat Sensor Heartbeat sensor TCRT100 in fig. 4 consists of both the infrared light emitter diode and the detector are arranged side by side in a leaded package. The output produced is a digital pulse which is synchronous with the heart beat. The output pulse can be fed to an ADC channel of a microcontroller for processing and retrieving the heart rate in beats per minute (BPM). Fig. 2 Block diagram of health monitoring system A. Temperature Sensor III. SENSORS The body temperature is measured by using the temperature sensor LM35[2]. It is a three terminal device. Pin number one is 5 volt voltage supply and three are for ground. Pin two is analog voltage output with respect to temperature. There is no need of extra circuitry to operate it. PIC16F877A microcontroller is used to read temperature value. The Relation between the temperature and analog output voltage is: 1 o C = 10m volt (1) Hence for every 1 degree increase in temperature there will be a increment of 10m volt in output voltage of LM35 sensor. The output of sensor is given to analog channel of PIC16F877A. Now after reading ADC value, using voltage and temperature relationship voltage is converted into temperature..these conversion has been done through programming. Fig. 3 Temperature Sensor Fig. 4 Heartbeat Sensor Photoplethysmography(PPG) is a non-invasive method used in measuring the variation of blood volume in tissues by a light source and a detector. The blood volume changes in synchronous to the heart beat, hence this technique is used to calculate the heart rate[4]. The basic types of photoplethysmography are transmittance and reflectance. In the transmittance PPG, a light source is emitted into the tissue and a photo detector which is in the opposite side to the tissue measures the resultant light. Due to the limited penetration of the light intensity through the tissue of organ, transmittance PPG is applied to the finger or the ear lobe which are the restricted body parts. However, in the reflectance PPG, the light source and the detector, placed on the same side of a body part. The light is then emitted into the tissue, the reflected light is therefore measured by the detector. As the light doesn t need to penetrate through the body, the reflectance PPG can be applicable to any parts of human body. According to the pulsatile blood flow, the detected light reflected from or transmitted through the body part will fluctuates as the beat of the heart. The PPG signal consists of two components, referred to as AC and DC. The AC component is mainly due to the pulsatile variation in arterial blood volume, that is synchronous with the heart beat. Therefore, AC component is rendered as the source of heart rate information. This AC component is superimposed with the large DC component which relates the tissues and the average blood volume. Thus, DC component should be removed to measure the AC waveform that consists of high signal-to-noise ratio. The DC component. can be get rid by passing the output from the sensor through a RC high-pass filter (HPF). The HPF sets the cut-off frequency to 0.7 Hz. In the next stage, an active low-pass filter (LPF) is made of an Op-Amp circuit. The LPF sets the cut-off frequency and gain to 2.34 Hz and 101, respectively. Thus the HPF and LPF, combination helps to 210

3 remove the unwanted DC signal and also the high frequency noise which includes 60 Hz (50 Hz in some countries), this amplifies the low amplitude pulse signal (AC component)10times. The output obtained from the first signal conditioning stage leads to a similar HPF/LPF combination which under goes further filtering and amplification. So, the cascading of two stages leads to calculation of the total voltage which is 101*101 = These two stages consisting of filtering and then amplification process converts the input PPG signals to approximate TTL pulses, which are synchronous along with the heart beat. The heart rate (BPM) are related to the frequency (f) of these pulses which is denoted as follows, The rise of heart rate abruptly increases gradually during exercises and then returns slowly back to the rest value after exercise. The rate at which the pulse goes back to normal forms an indication of the fitness of the person. The heart rate lower than the normal forms an indication of a condition termed as bradycardia, while the rate higher than the normal are termed as tachycardia. Table I shows the heart rate of students during the exercising period. Table I Heart rate of students during Exercise Heart Rate(BPM) Students 1min Exercise 2mins Exercise 3mins Exercise 4mins exercise I II III IV V Average Fig. 5 Pulse Oximeter Sensor Two wavelengths, 660 nanometers (red) and 940 nanometers (near infrared) of light are used. At 660nm, reduced hemoglobin absorbs light ten times more than oxy hemoglobin. Similarly, at (940nm), the oxy hemoglobin absorbs light greater than the reduced hemoglobin as shown in fig. 6. By the direct absorption of light in pulse oximetry senses the ratio of pulsatile to non-pulsatile light at the two wavelengths, it is then translated to a function of the arterial oxygen saturation through complex signal processing. C. Pulse Oximeter Oxygen gas is essential for human to survive. It is integral for countless biological processes. The circulatory system performs the oxygen transportation throughout the human body and more specifically, hemoglobin in red blood cells. By detecting the amount of oxygen in blood, any critical condition regarding medical care can be obtained. Now-a-days, Pulse oximetry is a standard device for measuring the blood-oxygen saturation in the operating room. This device use of light to measure the oxygen content in blood and heartbeat rate is called pulse oximetry. Pulse oximetry depends on sensing of a physiological signal called Photoplethysmography (PPG),which gives the optical measurement of blood volume in arteries.pulse oximetry obtains PPG signal by irradiating two wavelengths of light such as Infrared and red LED through the tissue and compares the absorption coefficient of light by blood under these two wavelengths. This comparison helps for the measurement of the oxygen content of blood and is known as blood oxygen saturation[1]. Fig. 6 Light absorption characteristics of HbO2 and Hb at different wavelengths The red blood cells are made up of protein molecules are known as Hemoglobin The principle of Hemoglobin is to carry oxygen from the lungs to the body's tissues and returns carbon dioxide from the tissues back to the lungs. Hemoglobin with more oxygen content is called oxygenated hemoglobin (HbO 2 ) and less oxygen content is called is called deoxygenated hemoglobin(hb). The ratio of oxygenated hemoglobin to deoxygenated hemoglobin is called oxygen saturation. Hence, 211

4 D. ph Level Sensor ph changes occur in the oral cavity, which are indicative of bacterial activity leading to dental caries. ph measurement is necessary as it measures whether the solution is acidity or basic. The sustainability of living things are based on the maintenance of proper ph level. The internal mechanisms of all human beings and animals rely on the maintenance of the ph level in their blood. The blood contents in our veins must consists of a ph level between 7.35 and The level exceeding this range nearly as one-tenth of a ph unit would be proved as fatal. Fig. 7 shows the ph glass electrode. range of 0-14 generates the output voltage from 0 to 5 V. The op-amp generally used was IC and IC2 CA3140. Fig. 8 ph probe Amplifier The Fig. 8 shows the amplifier circuit, which was used to condition the small voltage signal of ph probe. The amplifier was used in an inverting configuration. This design was made such that, by indicating the solution was neutral at ph 7 (i.e. water) its output voltage was 2.5 V (ranges 0-5V), for an acidic solution (ph 4) the output voltage was 1.429V and for a solution which was alkaline (ph 9.2) the output voltage was The designed circuit would be more reliable due to its accuracy and inexpensive. Now the output from the amplifier circuit was sent to the PIC microcontroller. Fig. 7 ph Glass electrode 1) Development of ph meter: A ph probe has the capability to generate different voltage levels with different solutions of different ph. In neutral and acidic solutions (below ph 7) a positive output voltage is generated whereas in basic solutions (above ph 7), a negative output voltage is generated. So an ideal ph probe, may give either positive or negative voltage outputs proportional to the acidity or alkalinity of the test solution. The output of a ph probe is in the millivolt range. The sensor selected was a general purpose glass electrode. It is a standard laboratory use electrode which when inserted in a solution, produces a small voltage (in mv), which is proportional to hydrogen ion concentration. It has little ball at the tip with a special ph glass. The probe output was fed into the amplifier through a shielded cable. The output of this ph sensor is very weak and the voltage very low. It requires additional circuitry for amplification and stable output voltage. 2) ph probe Amplifier The output voltage, for various ph values can be adjusted by making connection to amplifier circuit. The volt/ph conversion was done using op-amp amplifiers, hence the ph E. ECG Sensor The Electrocardiograph (ECG) signal is a diagnostic tool beating, which is the main function of heart. The principal corresponding signal frequency also range of 0.01 to 250 Hz. Electrocardiography is the measurement of the electrical activity of the heart. Electrical sensing devices or electrodes are placed strategically on top of the body to detect the electrical activity of the heart and diagnose patients with different heart anomalies. The trace depends on the position of the lead. The leads placed on the body can be described as a positive lead and a negative lead [3]. The fig. 9 shows the main causes of positive and negative deflection occurrence in the heart. Fig. 9 Causes of deflection The electrical impulse that is generated in the heart travels in parallel to the direction of the lead. A positive deflection takes place, if the impulse moves toward the positive lead and 212

5 a negative deflection takes place if the direction of the impulse moves toward the negative lead. Electrodes are placed in the arms and legs, which forms the Einthoven's triangle. Fig. 10 depicts the Einthoven's triangle which is composed of Leads I, II, and III. free C compilers which are provided to a wide variety of development platforms. These compilers generally form a part of an IDEs with ICD support, single stepping, breakpoints, and an assembly window. B. HyperTerminal Software HyperTerminal can be used to set up a dial-up connection to another computer through the internal modem using Telnet It can also access, bulletin board service (BBS) to another computer. This process is mainly used to set up a connection to perform data transfer between two computers (such as one desktop computer and a portable computer) using only the serial ports. The serial-port controls all the external devices or systems such as scientific instruments, radio communications stations. HyperTerminal was designed as a troubleshooting tool during the process of setting up and in using a modem. Fig. 10 Three lead system "Three lead" ECG, is made with the measurements taken from any three points on the body which is known as the Einthoven's recording.(defining the "Einthoven triangle" - an equilateral triangle with the heart at the center.) The difference between potential readings from L1 and L2 is what is used to make the trace of the ECG output. The L3 connection is designed to establish a common ground for the body and to the recording device. V. EXPERIMENTAL RESULTS By implementing the wireless health monitoring system using PIC Microcontroller, these are the results displayed using hyper terminal in PC. The ZigBee wireless module is used to receive data from the remote patient. Fig. 12 shows the output value obtained. Fig.11 Typical ECG waveform IV. PIC SOFTWARE DETAILS MikroC Pro and Proteus is used for programming and simulating the Microcontroller. HyperTerminal software is used for displaying the output data. A. MikroC Pro The PIC is programmed using MikroC which is the acronym for Micro-Controller Operating Systems. It is intended for use in embedded systems. Embedded C remains a very popular language for micro-controller developers due to the code efficiency and reduced overhead and development time, so that is used here. Covers low-level control and is considered more readable than assembly. There exists many Fig. 12 Implementation of heartbeat measurement VI. CONCLUSION This paper presents the design and implementation of wireless sensor network for health monitoring system by using ZigBee module. It is concluded that Programmable Interface Controller (PIC) has been the low cost implementation used 213

6 for recording and transmitting the bio-medical signals by wireless technology and very useful to the remote patients. This system was developed to minimize the device s size and allow for daily life usage. This system can also be made to include other health monitoring module like EMG, EEG for complete monitoring system. REFERENCES [1] D.J.R.Kirankumar and Nalini Kotnana, Design and Implementation of portable health monitoring system using PSoC mixed signal array chip, International Journal of Recent technology and Engineering(IJRTE),vol.1,Issue 3,August 2012,ISSN [2] Md.Moyeed Abrar and Rajendra R.Patil, Multipoint temperature data logger and display on PC through ZigBee using PSoC,International Journal of Advanced Research in Computer and Communication Engineering, Vol. 2,Issue 9, September 2013,ISSN [3] R.Prakash and B.Paulchamy, Remote monitoring of ECG and Body Temperature signals, International Journal of Innovative Research in Science,Engineering and Technology,Vol.3,Issue 5,May 2014,ISSN [4] S.Josephine Selvarani, Online Health Monitoring System Using ZigBee, International journal on Computer science and Engineering(IJCSE),Vol.3,No.4,April 2011,ISSN [5] Mahima Rathore, Design and prototyping of PSoC based Pulse Oximeter, International Journal of Scientific And Engineering Research,Vol.3,Issue 10,October 2012,ISSN S.Sakuntala is pursuing B.E degree in the Department of Electronics and Communication Engineering at Mepco Schlenk Engineering College, Sivakasi in She is a member of Institution of Electronics and Telecommunication Engineers. Her area of interest is Digital Electronics, Embedded Systems and Computer Networks. She has worked on the mini project based on microcontroller in 2013.Her aim is to do Higher Studies. R.Ramya Dharshini is doing final year B.E in the Department of Electronics and Communication Engineering at Mepco Schlenk Engineering College, Sivakasi in She is also a member of Institution of Electronics and Telecommunication Engineers. She is interested in the Wireless Communication field. Her ambition is to seek job in research field. Meenalakshmi M was born at Tamil Nadu, India in the year 1987.She pursued her B.E., in Electronics and Communication Engineering from Mepco Schlenk Engineering College, Sivakasi in the year 2008 and M.E., Embedded System Technologies from Srisairam Engineering College, Chennai in the year 2013.She has published two international journals and presented papers in International and National conferences Her research interest includes Embedded Systems, Renewable energy sources, WSN. Mrs. Meenalakshmi is a member of professional bodies like IETE and ISTE. 214