PE2-3.2 Transducers, Electrodes & Cardiovascular Measurement
You can distinguish active from passive transducers and describe biopotential electrodes, and measure blood pressure, blood flow, cardiac output and heart sounds, and outline patient monitoring, pacemakers and defibrillators.
The electrode is the most under-appreciated component in the whole chain: it converts ionic current in tissue into electronic current in a wire, and its half-cell potential and drift cause more measurement trouble than any amplifier. Blood pressure measurement is worth studying in both forms, since the cuff method everyone knows is indirect and the direct method is what an ICU actually uses. The patient monitoring material grounds the subject — these are instruments that people's lives depend on, which is the right frame for the safety requirements.
Work through these
Transducer principles; active and passive transducers
How a physical quantity becomes an electrical one, and the split by whether the device needs power. It is the frame for the whole measurement half of this subject.
Biopotential electrodes and electrode theory
The interface between an electrode and tissue, which is chemistry rather than a wire. The half-cell potential and the motion artefact both come from here.
Biochemical transducers
Measuring chemistry rather than voltage, which is how blood gases and glucose are sensed. A different physical principle from everything else in this topic.
The heart and cardiovascular system; blood pressure and blood flow
The organ and the circulation, described so the measurements below have something to refer to. Read it as the anatomy the instruments assume.
Heart sounds and the ECG
The two signals the heart produces, one acoustic and one electrical. Relating them in time is what makes both interpretable.
Measurement of blood pressure and blood flow
Measuring pressure and flow, invasively and otherwise. The non-invasive methods trade accuracy for not putting a catheter in someone.
Measurement of cardiac output; heart sounds and PCG
Measuring how much blood the heart moves, which is harder than pressure and more informative. The acoustic recording is treated alongside it.
Elements of intensive care and patient monitoring systems
What a critical care unit is made of, and why several instruments are combined. It is the setting most of this equipment is used in.
Other instruments; organization of the hospital for patient care monitoring
The remaining instruments, and how a hospital arranges monitoring across wards. It is context rather than technique, and it explains many design constraints.
Pacemakers and defibrillators
The two devices that put energy into the heart rather than measuring it. Safety requirements here are unlike anything else in the course.
Sign in to keep your progress.
Free resources
We haven't checked most of these for screen reader use yet.
Links last checked 30 Aug 2026.
Stuck here?
Ask a mentor. A real person answers, and they can see exactly which topic you're on. Usually within a couple of working days.
Checking your session…
Topics shown in module order.