Biomedical Remote Patient Monitoring System - Engineering Project

The aim of patient monitoring system is to have a quantities assessment of the important physiological variables of the patient during the critical period of biological functions. For the diagnostic and research purpose, it is necessary to know their proper heart beat or its trend of change. Patient monitoring systems are used for measuring continuously or at regular intervals, automatically, the value of patients physiological parameters. In this project the micro controller 89s52 will take proper readings from the sensors via ADC and will send it to PC and hence it is the heart of the system. We are going to supervise some of the important parameters of the patient under treatment including

Body temperature

Pulse rate

ECG

Development of modern patient monitoring systems demands the intensive use of sophisticated real time software technology and an open architecture system design. However current monitoring systems are still developed in a closed architecture supporting only a limited number of vendor-specific communication interfaces. This project deals with the design aspects of a modern patient monitoring system on an open architecture which supports standard communication protocols allowing flexible telemedical interfacing. There are also various categories of patient monitoring systems: wireless patient monitoring system, multipatient patient monitoring system and remote patient monitoring system. The system comprises of sensors for measuring real-time physiological parameters, such as ECG and Saturation of oxygen, from patients. The system also comprises a monitoring terminal for monitoring these parameters. A central processing system processes the real-time physiological parameters and their analysis, in combination with the relevant historical medical data, for each patient. The medical staff uses this processed data to provide required medical care to the patients. Further, the system provides remote access of patient’s data, via remote access stations.

ADC

I used MCP2302 as ADC, providing inputs from ECG section and temperature sensor to the ADC. It converts analog data into digital data and it sends this data to the microcontroller which in turn sends it to PC and LCD display.

MICROCONTROLLER

I used 89s52 microcontroller which takes digitalized input from ADC and pulse rate section.  

LCD

The microcontroller is interfaced with 16*2 LCD which is used to display pulse rate and temperature readings which are being monitored by their respective sensors.

Send the parameters from the microcontroller to the PC via RS232. Display can be created for these parameters on PC using various available softwares. I had used Visual basic to create graphical display.

Use LM35 to measure the temperature of the patient. The value read is given to ADC which converts the analog data into digital data and sends it to microcontroller.

Use a LDR and LED to measure the pulse rate. The measured value is then amplified and passed through high pass, low pass filters and through notch filter and again amplified in the end to get +2.5V/-2.5V. We send this digitized output to adder circuit which shifts the output to 0-5V range. Then we send this output directly to the microcontroller.

Use three carbon electrodes to measure the condition of the heart. We can attach these electrodes to chest, ankles and wrists. These are amplified and signal conditioned and coupled to the high pass and low pass filters via opto coupler so as to avoid shocks. Take the readings between 5-35 Hz. Use notch filter to avoid 50 Hz noise present in the surroundings due to power supply lines. We get +2.5/-2.5 V output which we change to 0-5V by adding adder circuit.

INSTRUMENTATION AMPLIFIER AD 620

The AD620 is a low cost, high accuracy instrumentation amplifier that requires only one external resistor to set gains of 1 to1000. Furthermore, the AD 620 features 8-lead SOIC24 and DIP11 packaging that is smaller than discrete designs, and offers lower power (only 1.3 mA max supply current), making it a good fit for battery powered, portable (or remote) applications. The AD620, with its high accuracy of 40 ppm maximum nonlinearity, low offset voltage of 50 μV max and offset drift of 0.6 μV/°C max, is ideal for use in precision data acquisition systems, such as weigh scales and transducer interfaces. Furthermore, the low noise, low input bias current and low power of the AD620 make it well suited for medical applications such as ECG and noninvasive blood pressure monitors.