Instrumentation - Intro to Biomedical Engineering

Explore complex numbers central to signals and systems, including real and imaginary components, magnitude, and phase, and express them with e^(j theta) and z = a + bj.

examine a complex function example to compute magnitude and phase angle, using complex conjugate multiplication and real and imaginary numbers from signals and systems.

Explore how noise distorts signals and affects analysis, including voltage noise and environmental noise at 60 Hz. Learn how signal-to-noise ratio in decibels and both amplitude and power forms relate.

Explore the differences between discrete and continuous signals and relate them to analog and digital readings, including periodic signals and duty cycle, to guide instrument selection.

Examine the four main signal types—sinusoidal, exponential, delta (impulse), and rectangle functions—and their roles in signal and system analysis, including linearity.

Combine the four basic signal types, rectangular, impulse, exponential, and sinusoidal, to build a time-gated signal composed of five rectangular pulses, repeated every 2T with each pulse spanning from -tau/2 to tau/2. Derive the final expression using a summation of five time-shifted rectangular pulses with amplitude a, and multiply the train by cosine omega T to produce the cosine-modulated signal.

Explore impulse responses and delta functions, learn how delta inputs produce system outputs, and apply the convolution integral and frequency response to analyze linear time-invariant systems.

Explores impulse responses and the frequency response of a linear time invariant system using convolution to derive the output for x(t)=10 cos(60 t+45°) via magnitude and phase.

Explore Fourier transforms and Fourier series, showing how signals decompose into frequency components and how time-domain and frequency-domain representations relate, with sinusoidal bases and periodicity.

Learn how sampling converts a continuous biomedical signal into discrete values with constant time increments, and how the Nyquist rate and anti-aliasing filters prevent signal distortion.

Explore how data acquisition converts analog and digital signals from biomedical sensors into digital values for computer analysis, using signal conditioning circuitry, and analog-to-digital and digital-to-analog converters.

Explore how data acquisition systems convert analog sensor signals to digital data through sampling, quantization, and bit-depth concepts, with practical math for precision and quantization levels.

The lecture reviews sampling concepts, Nyquist rate, and how discrete sampling enables accurate signal reconstruction in data acquisition, with attention to sampling rate, anti-aliasing, and grounded versus floating sources.

Explore digital to analog conversion and how digital signals translate to voltage levels. Discuss pulse width modulation and duty cycle, low pass filter, and sampling rates from kilohertz to megahertz.

Demonstrate how pulse width modulation enables a digital to analog conversion, then calculate a duty cycle from on and off intervals and derive the average voltage.

Review the core concepts of data acquisition systems, analog-to-digital conversion, sampling, anti-aliasing, and digital-to-analog conversion, and prepare for the quiz by mastering duty cycle calculations and Nyquist rate.

Reinforce core data acquisition concepts in biomedical instrumentation by explaining essential components—sensors, signal conditioning, and analog-to-digital converters—through solved problems, including voltage range calculations, sampling rate, and duty cycle.

Explore the basics of circuit components—wires, resistors, and the voltage source—and how resistance governs current, with color bands determining resistor values and tolerances.

Explore potentiometers and voltage dividers, learn how adjustable resistance controls circuit output, including digital potentiometers, their applications in volume control, and basic divider formulas.

Solve a loaded voltage divider to find rl. Use 10 V input with r1 = 100 ohms and r2 = 1500 ohms to yield vout = 6 V.

Explore how LEDs operate, including anode and cathode orientation, brightness control by current, and the necessity of a series resistor, alongside capacitors that store charge for energy and filtering.

Explore operational amplifiers, high-gain, high-input-impedance devices that amplify weak signals from the body; learn about inverting and non-inverting configurations, frequency dependence, and instrument amplifiers.

Explore instrumentation amplifiers that provide large gain for very low level biomedical signals amid noise with a three-op-amp design, high input impedance, and high common-mode rejection ratio.

Explore how microcontrollers provide simple processing systems to control and analyze signals, focusing on open-source Arduino Uno/Nano, sensors, PWM, ADC, digital and analog I/O for beginners.

Discover how Arduino microcontrollers perform single tasks with a simple setup and loop code structure. Learn how code is written on a computer, uploaded, and exchanged via serial communication.

Review quiz concepts on Arduino microcontroller hardware and software, including wires, resistors, potential emitters, capacitors, and leds. Understand operational and instrumentation amplifiers and the Arduino basics, pins, applications, and coding.

Recap explains volume control with a potentiometer, light emission via electron-to-photon conversion, and instrumentation amplifier traits such as high input impedance and gain, noting Arduino's limitations.

Learn the 555 timer, a versatile integrated circuit for timer, delay, and pulse generation; explore monostable, astable, and bistable operation and its role in power instrumentation.

Explore the stable mode of the 555 timer as a free-running oscillator that generates continuous rectangular pulses, with frequency and duty cycle set by two resistors and one capacitor.

Learn how the Schmidt trigger cleans noisy signals into binary outputs, converting analog waveforms to rectangular pulses with hysteresis for reliable biomedical signal processing.

Power supplies convert ac wall voltage to dc to power biomedical systems with stable, low-noise output. Compare lab, standard, usb, and battery supplies for voltage, current, noise, and stability considerations.

Explore dc power supplies, regulated vs unregulated outputs, ripple, and the trade-offs of voltage regulators and low dropout regulators for a clean, stable signal.

Review the concepts from 555 timers, modes and duty cycles, Schmitt triggers and auto Schmitt history, and AC and DC power supplies with voltage dropout regulators and pros and cons.

This quiz recap covers chapter 5 questions, clarifying the 555 timer’s basic limitation and that two resistors and a capacitor set a stable frequency for a single-trigger response.

Understand how materials absorb photon energy by electrons, with absorption depending on wavelength and luminescence emitting longer wavelengths; Beer-Lambert law links attenuation to concentration for spectroscopy and fluorescence applications.

Apply the Beer-Lambert law to a concrete problem: compute the light attenuation for a 5 cm cube with 250 mW/cm^2 incident intensity and 30,000 molecules/cm^3.

Understand fluorescence, the emission of light after absorption-driven by discrete energy-state transitions. Learn how lab setups, including a laser source, excitation and emission filters, and detectors, quantify fluorescence properties.

Explore optical transducers that convert light into electronic signals, enabling non-invasive biomedical sensing of blood properties and heart rate via wavelengths from infrared to ultraviolet.

Explore how interference, including constructive and destructive types, affects optical transducer signals, and understand reflection as a wave direction change at the plane of incidents with the angle of incidence.

Photodiodes are semiconductor devices that convert light into a photocurrent via photon absorption. Responsivity depends on detector material and can be tailored with filters and lenses for varied applications.

Learn how optical detectors act as transducers that convert optical signals into electrical current, guided by responsivity, and compare photodiodes, avalanche photodiodes, photo cells, phototransistors, and photomultiplier tubes.

Learn how transimpedance amplifiers convert current from optical detectors into a usable voltage, filter and amplify it for easy analysis with data acquisition systems, including photodiodes, pressure transducers, and accelerometers.

Review absorption spectrum and luminescence relationships, Beer Lambert equations, fluorescence, optical transducers, photodiodes, and optical detectors; cover interference, reflection, and trans impedance amplifiers for quiz readiness.

Explore how absorbed photons relate to luminescence wavelength in the absorption spectrum, review absorption-based methods like pulse oximetry, and outline trans impedance amplifier steps.

Explore how the respiratory system transports oxygen through the lungs and alveoli, how hemoglobin carries oxygen (oxyhemoglobin) and releases carbon dioxide, and the basics of pulse oximetry.

Explore pulse oximetry, a noninvasive, real-time device using two wavelengths to measure oxygen saturation and hemoglobin status for clinical monitoring.

Explore the pulse oximeter circuitry, from finger clip and led drivers to the photodiode detector, filters, amplifiers, analog-to-digital converter, and microprocessor that quantify oxygen levels.

Examine pulse oximeter waveforms, from normal signals to low perfusion, noise artifacts, and motion artifacts, then compute SpO2 using AC/DC ratios at 660 and 900 nanometers.

Explain pulse oximeter waveforms, how interference affects detection, and walk through an example using 660 nm and 940 nm to calculate oxygen concentration, yielding about 82.2% and noting clinical ranges.

Explore noninvasive pulse oximetry applications, including elaborate sensors for mice and lab rats, near-infrared spectroscopy, and brain hemoglobin mapping with optical methods.

Review pulse oximetry fundamentals, oxygen transport, and hemoglobin functions, and explore pulse oximeter instrumentation, waveform calculations, and other practical applications for the final quiz.

Review the final quiz on oxygen transport, diffusion in the lungs, hemoglobin’s role, and pulse oximetry, including LED wavelengths and AC/DC ratio calculations for oxygenation in biomedical engineering instrumentation.