Vidya Muthukrishnan 
What is a Surface Electrode? Surface electrode measures the potential available from the surface of the skin. It senses the signal from heart, brain and nerves. Larger surface electrodes sense the ECG signals. Smaller surface electrodes sense the EMG and EEG signals. The types of surface electrodes are as follows. Metal Plate Electrodes ECG measurements … Read more
Non-electrical parameters such as temperature, heart sound, blood pressure are measured from the human body with electronic equipment. Transducers are the devices that convert biological parameters to electrical signals. The process of conversion is Transduction. Generally, transducers convert one form of energy into another form of energy.There are two main types of transducers: active and … Read more
Application of Piezoelectric Transducer Crystal microphone measures and records the Heart sounds (Phonocardiography). The microphone operates in the flat frequency range of 20 to 1000 Hz, which suppresses the breathing sounds and room noise. Sounds from heart chambers are measured with Catheter-tip piezoelectric sensors. A piezoelectric crystal detects Korotkoff sounds, crucial for measuring systolic and … Read more
When recording biopotentials noise and drift are the two problems encountered. Noise is due to the recording device and by the patient when they move. Drift is a shift in baseline created due to various thermal effects. A DC amplifier has a shift or sudden peak in the output when the input is zero. Therefore, … Read more
ECG Waveform This is what an ECG waveform looks like: Depolarisation When electrical activity occurs, heart muscle fibers contract, producing movement. This condition is referred to as depolarisation. When blood is pumped around the body, the heart chambers contract, called systolic pressure. Repolarisation The realxation of heart muscles are called electrical repolarisation. Relaxed heart chambers … Read more
Heart electrical signals are measured using surface electrodes. These electrodes detect the potential in the heart and conduct it to the body surface. Standardized positions are used to ensure accurate ECG recordings. There are three main types of electrode systems: Bipolar Limb leads – Standard Lead I, Lead II and Lead III This lead system … Read more
What are Electrodes? Electrodes are defined as solid electric conductors that let electric current enter or leave an electrolytic cell, converting ionic potentials to electronic potentials. Different types of electrodes are used for biological measurements depending on where the bioelectric signals are taken from. These electrodes can acquire signals like ECG, EEG, and EMG.There are … Read more
EEG Lead System The International Federation of EEG Society recommends the 10-20 electrode placement system for EEG recording. This system uses silver/silver chloride electrodes as surface electrodes. The distances between electrodes on the scalp are set at 10% and 20% of the distance between specific points. Nasion and Inion are two reference points on the … Read more
What is Biomedical Instrumentation? Biomedical instrumentation applies engineering and technology to solve medical problems in diagnosis, treatment, and disease prevention. The field combines principles of biophysics and biochemistry—where physics and chemistry meet biology—with medical and engineering practices. Biomedical instrumentation measures biological signals such as ECG and EMG, aiding physicians in diagnosing and treating patients. Designing … Read more