Electronics in Biomedical Engineering: Theory & Repair

Understand current, voltage, and resistance as core electrical quantities. Learn how current flows, how voltage drives it, and how resistance shapes it with Ohm's law, power, and energy concepts.

Explain how resistors reduce current and voltage, measure resistance in ohms, and decode color bands for four-, five-, and six-band resistors, including variable resistors such as trimmers and potentiometers.

Learn how the light dependent resistor (LDR) changes resistance with light from up to 1 megaohm in darkness to 10–20 kiloohms in light, and its use in alarms and clocks.

Explore the basics of the diode, a semiconductor one-way switch from anode to cathode. See how it rectifies AC to pulsating DC and note forward drops for germanium and silicon.

Explore the Zener diode, a diode that conducts forward and in reverse beyond its Zener breakdown voltage, and understand its symbol, anode, cathode, and a 12 V circuit example.

Examine how ir leds emit infrared light and pair with photodiodes to form ir sensors. See how white or light surfaces reflect ir light while dark colors absorb it.

Explore how a capacitor stores energy between two plates with a dielectric, charging and discharging to smooth dc after a diode bridge. Use microfarads and farads to quantify its behavior.

Explain what integrated circuits are, a tiny chip uniting resistors, transistors, capacitors, and diodes; understand pin numbering and polarity marks, and programmable ICs and Arduino platforms.

Explore circuit analysis techniques for electronics in biomedical engineering, including ohm's law, Wheatstone bridge, node voltage method, mesh analysis, Norton and Thevenin theorems, superposition, RMS in AC, and parallel RLC.

Analog signals are continuous voltage changes transmitted as a continuous wave, used in video and audio transmissions, while digital signals use two-level on/off values, staying robust to noise.

Explore how the SAR ADC uses stepwise comparisons and a successive approximation register to convert analog voltages, such as 11.2 V, into digital values with high speed and accuracy.

Explore the differences between microprocessors and microcontrollers, including architecture and integrated peripherals, with Arduino and Raspberry Pi as practical examples in embedded systems.

Learn how to read analog inputs on an Arduino using a potentiometer to vary a led blink rate, wiring A0, a potentiometer, 5 volts, and ground.

Build a dimmable LED with an Arduino using analogWrite for PWM on pin 11, reading a potentiometer on analog input 0 and monitoring via the serial monitor.

Build an ecg using an Arduino Uno and the ad8232 sensor, wiring power, ground, and outputs to an analog input, with electrode leads and a heartbeat led indicator.

Define the diode as a two-terminal pn junction that conducts in one direction. Examine the depletion region, forward and reverse bias, and roles in rectifiers, clipping, regulation, and emitting diodes.

Explore the gain of op amps, including open-loop and closed-loop gain, and how negative feedback sets inverting and non-inverting configurations using resistor relationships.

Explore op-amp basics through inverting and non-inverting amplifier examples, and demonstrate a voltage follower, using feedback resistors to set gain and understand output relationships.

Explore low pass filters using an integrating op-amp, including circuit configuration with a capacitor in the feedback path, and how integration shapes low-frequency signals while attenuating high frequencies.

Explore how low-pass filters pass low-frequency signals and attenuate high-frequency noise using resistor-capacitor circuits, and apply this to audio, communication systems, and biomedical engineering.

Explore bandstop filters, or notch filters, how they block a notch frequency while passing other frequencies, and their circuit components and bandwidth concepts.

Learn the principles of heartbeat sensing with a simple IR-based sensor, comparing transmission and reflection methods using an IR LED and photodiode, and how blood absorption yields the pulse.

Explore Proteus 8 professional for designing and simulating circuits, from creating a new project and adding resistors, capacitors, regulators, and LEDs to running simulations and measuring voltages with virtual instruments.

Assemble the circuit on a breadboard to test functionality, using positive and negative rails and middle columns. Connect the IC, LED, photodiode, resistors in series or parallel, and 9-V battery.