Final Prep 2025 - Biomedical Imaging and Analysis

Vocabulary practice flashcards covering biomedical imaging, electronics, filtration, optics, and molecular sequencing based on the Final Prep 2025 lecture notes.

Minimally Invasive Procedure

A procedure, such as adding a contrast agent for MRI, where a substance is injected into the bloodstream or a body cavity, crossing the skin barrier.

Ohmic Response (Slope Analysis)

In an $I$ vs. $V$ plot for a resistor where $I = \frac{V}{R}$, a higher slope represents lower resistance ($R$) because the slope equals $\frac{1}{R}$.

Diode IV Characteristics

A non-linear, rectifying device with an exponential IV curve defined by the equation $I = I_0(e^{\frac{V}{nV_T}} - 1)$, allowing current to flow easily in forward bias but blocking it in reverse.

Battery IV Curve

Considered linear, though an ideal battery shows a slight linear droop due to internal resistance, defined by $V_{out} = V_{emf} - I \times R_{internal}$.

Resistivity ($\rho$)

An intrinsic material property independent of shape or size that describes how strongly a material opposes current flow; related to resistance by $R = \frac{\rho L}{A}$.

Digital Multimeter (DMM) Voltage Mode

A mode used to measure potential difference ($V$) characterized by high input impedance to avoid loading the circuit.

Digital Multimeter (DMM) Current Mode

A mode used to measure current ($A$) where the device is inserted in series and must have near-zero input impedance.

Thermistor

A type of resistive sensor whose resistance changes with temperature, often featuring a negative temperature coefficient (NTC) where resistance decreases as temperature increases.

Strain Gauge

A sensor that changes resistance when mechanical strain stretches or compresses the material.

Voltage Divider Rule

In a series circuit, the largest voltage drop occurs over the resistor with the highest resistance, calculated as $V_{out} = V_{in} \times \frac{R_2}{R_1 + R_2}$.

Biphasic Pulses

Current pulses used in defibrillators that reverse polarity midway through to reduce energy/charge delivered and minimize myocardial damage compared to monophasic pulses.

Cutoff Frequency ($f_c$)

The $-3\text{ dB}$ point on a Bode plot representing the boundary between the passband and stopband, where output power is half the input power; for a first-order RC filter, f_c = \frac{1}{2\text{\textpi} RC}.

Filter Attenuation Calculation

Determined by taking the vector magnitude of the transfer function, |H(j\text{\textomega})| = \text{\textsqrt{real}^2 + imaginary^2}.

Filter Order

A design characteristic where increasing the order increases the slope of the Bode plot rolloff (e.g., 1st order is $-20\text{ dB/decade}$, 2nd order is $-40\text{ dB/decade}$).

Ideal Op-amp Input Impedance

High input impedance, which is ideally infinite, meaning the component draws zero current at its input terminals.

Biopotentials

Electrical signals (like ECG or EEG) produced in the body by the selective permeability of ion-selective membrane channels to specific ions such as $Na^+$, $K^+$, $Ca^{2+}$, and $Cl^-$.

Sensor Response Regimes

The three stages of a sensor's performance: Below Limit of Detection (LOD), Dynamic Range, and the Saturation regime.

Single-Channel Light Detectors

Devices such as the Photodiode, Photomultiplier Tube (PMT), and Photoresistor used to detect light intensity.

Multi-Channel Light Detector Arrays

Imaging sensors such as CCD (Charge-Coupled Device) and CMOS (Complementary Metal-Oxide-Semiconductor) arrays.

Nucleic Acid and Protein UV Absorption

Specific wavelengths where biological molecules absorb light: Nucleic acids at $260\text{ nm}$ and proteins at $280\text{ nm}$.

Stokes Shift

The phenomenon in fluorescence where an emitted photon has a longer wavelength (lower energy) than the absorbed excitation photon.

Raman Spectroscopy

A readout where a photon is scattered inelastically, losing energy based on the specific molecular bonds within the sample.

Turbidity

A methodology where photons are scattered by particles suspended in a fluid to measure concentration, also known as nephelometry or OD measurement.

Quantum Yield (\text{\textPhi})

The fraction of absorbed photons that are re-emitted as fluorescence, ranging from $0$ to $1$.

Chromatic Aberration

An optical lens defect where different wavelengths focus at different distances due to dispersion, resulting in color fringing.

Numerical Aperture (NA)

A lens property that describes the conical acceptance angle of light.

Dichroic Mirror

A wavelength-selective beamsplitter used in fluorescence microscopy to reflect excitation wavelengths and transmit emission wavelengths.

Photobleaching

The irreversible chemical destruction of a fluorophore caused by light-induced reactions, often involving oxygen.

Abbe Diffraction Limit

The physical limit preventing optical microscopes from visualizing nanoscale structures, defined by the formula d = \frac{\text{\textlambda}}{2 \times NA}.

X-ray Absorption Dependency

Absorption that depends predictably on the atomic number ($Z$) of elements, specifically following a $Z^3$ to $Z^4$ dependence.

X-ray Contrast Agents

Elements with high atomic numbers used for imaging, specifically Iodine ($Z = 53$) and Barium ($Z = 56$).

Computed Tomography (CT)

A biomedical imaging technology that uses a rotating X-ray source and detector array.

Radon Gas

The main source of background radiation in the United States, accounting for approximately 54\text{%} of average exposure.

MRI Contrast Mechanism

Based on spin-active nuclei, specifically the $^1H$ (hydrogen proton) and their $T1/T2$ relaxation differences.

Positron Emission Tomography (PET)

An imaging technology that localizes radiotracers (like $^{18}F\text{-FDG}$) by detecting coincident $511\text{ keV}$ gamma rays produced by positron-electron annihilation.

Ultrasound Transducer

A device using piezoelectric crystals (e.g., PZT) to convert electrical waveforms into mechanical pressure waves and vice versa.

Affinity Chromatography (His-tag)

A separation method for proteins using a poly-histidine sequence (6\text{\texttimes}His) that binds to nickel on a column.

SDS (Sodium Dodecyl Sulfate)

A detergent used in gel electrophoresis to give all proteins a uniform negative charge so they travel in the same direction.

Electroosmotic Flow (EOF)

The bulk fluid movement toward the cathode in capillary electrophoresis caused by an electric field acting on cations attracted to the silica wall.

Sanger Sequencing

A DNA sequencing method that uses dideoxynucleotides (ddNTPs) to cause chain termination, with fragments read via fluorescence.

Nanopore Sequencing

A DNA sequencing technology capable of identifying DNA base modifications without using fluorescence.

Indirect ELISA

A biochemical assay specifically used to detect antibodies by using an enzyme-conjugated detection antibody to produce a colored product.

Hydrodynamic Focusing

A technique in flow cytometry that uses sheath fluid to narrow the sample stream into a thin core to ensure cells pass through a laser one at a time.

Forward Scatter (FSC)

A flow cytometry channel that collects light diffracted at $0^\text{\textdegree}\text{--}10^\text{\textdegree}$ to determine cell size.

Side Scatter (SSC)

A flow cytometry channel that measures light scattered at $90^\text{\textdegree}$ to determine cell granularity or internal complexity.