Bioengineering 316: Biomedical Signals and Sensors Flashcards

Vocabulary terms and definitions covering materials, signal processing, filters, and ultrasound physics from the Bioengineering 316 final exam review.

Ag / AgCl

A material where current causes ions to leave or join its surface, making it suitable for reversible, non-polarizable electrodes.

Air

A material that should be avoided behind piezoelectric elements in an imaging probe and between the probe and the skin to ensure proper signal transmission.

Cardiac catheter

A device featuring a hydrophilic coating over electrical insulation to minimize the risk of microshock.

Lead zirconate titanate

A piezoelectric material, also known as PZT, used in imaging probes with a speed of sound of approximately $4000\,\text{m/s}$.

MOSFET

A device with an electron source and drain and a gate region coated by insulating material to allow only an electric field to pass across the gate.

Platinum or tungsten

Materials that do not oxidize easily and build up capacitive charge at their surface as current flows, making them polarizable electrode materials.

Polyvinylidene difluoride (PVDF)

A material used in biomedical applications with a speed of sound of $2200\,\text{m/s}$.

SiO2

The material used to coat the gate region in a MOSFET to prevent current from entering while allowing an electric field to pass.

IIR Filter

A type of filter with an infinite impulse response whose output depends on previous outputs as well as current and previous inputs.

Hamming window

A window function not used in IIR filters because the window would need to be infinitely long.

Frequency resolution ($\Delta f$)

The spacing between frequency bins in a discrete Fourier transform, defined as $\Delta f = \frac{1}{T} = \frac{f_s}{N}$.

Discrete Fourier Transform (DFT)

A formula used to convert discrete time signals into the frequency domain: $V(m) = \sum_{n=0}^{N-1} v(n) e^{-j 2\pi m n / N}$.

Continuous Fourier Transform

A mathematical operation represented by the formula $V(\omega) = \int_{-\infty}^{\infty} v(t) e^{-j\omega t} dt$.

Q (Quality factor)

A measure of resonance in a circuit defined by the formula $Q = \frac{\omega_0}{BW} = \frac{1}{R} \sqrt{\frac{L}{C}}$.

Doppler ultrasound shift

The change in frequency caused by motion, calculated as $\Delta f_{fus} = \frac{2v \cos(\theta)}{c} f$.

Resonant frequency ($\omega_0$)

The frequency in an RLC circuit determined by the product of inductance ($L$) and capacitance ($C$).

Phased array transducer

A transducer with multiple individually controllable concentric elements that allows for variable focus depth.

Dark field microscopy

A practical example of spatial high pass filtering in biomedical imaging.

Voltage resolution (q)

Calculated for an analog-to-digital converter using the formula $q = \frac{\Delta V}{2^b}$.

Instrumentation amplifier

The first component usually used in a sequence of circuits to process signals between EKG electrodes and an ADC.