Tlc272 Bio Amplifier — Biomedical Instrumentation & Clinical Sensing

Abstract — Tlc272 Bio Amplifier

Tlc272 Bio Amplifier: Biomedical Engineering, Medical Electronics & Bio-Signal Modeling Integrated Clinical Investigation: Bio-Sensors · Analog Front-Ends (AFE) · Diagnostic Waveforms · DSP Algorithms · ~7459 Words Chapter 1: Electrophysiological Foundations, Action Potentials & Clinical Significance A Bioamplifier is an electrophysiological device, a variation of the instrumentation amplifier , used to gather and increase the signal integrity of physiologic electrical activity for output to various sources. It may be an independent unit, or integrated into the electrodes.

Sensor Interfacing & Analog Front-End Conditioning

Efforts to amplify biosignals started with the development of electrocardiography . In 1887, Augustus Waller, a British physiologist, successfully measured the electrocardiograph of his dog using two buckets of saline, in which he submerged each of the front and the hind paws. A few months later, Waller successfully recorded the first human electrocardiography using the capillary electrometer. However, at the time of invention, Waller did not envision that electrocardiography would be used extensively in healthcare. The electrocardiograph was impractical to use until Willem Einthoven, a Dutch physiologist, innovated the use of the string galvanometer for cardiac signal amplification. Significant improvements in amplifier technologies led to the usage of smaller electrodes that were more easily attached to body parts. In the 1920s, a way to electrically amplify the cardiac signals using vacuum tubes was introduced, which quickly replaced the string galvanometer that amplified the signal mechanically. Vacuum tubes have a larger impedance, so the amplification was more robust. Also, its relatively small size compared to the string galvanometer contributed the widespread use of the vacuum tubes. Furthermore, the large metal buckets were no longer needed, as much smaller metal-plate electrodes were introduced. By the 1930s, electrocardiograph devices could be carried to the patient's home for the purpose of bedside monitoring. With the emergence of electronic amplification, it was quickly discovered that many features of the electrocardiography were revealed with various electrode placement.

Bio-Signal Waveform Analysis & Simulation Findings

Electrocardiography (ECG or EKG) records the electrical activity of the heart, across the surface of the thorax skin. The signals are detected by electrodes attached to the surface of the skin and recorded by a device external to the body. The amplitude of ECG ranges from 0.3 to 2 mV for the QRS complex, which is used to determine the interbeat interval from which the frequency is derived. The typical requirements for the amplifiers to be used in ECG include: Electromyography (EMG) records the electrical activity produced by skeletal muscles. It records various types of muscle signals from simple relaxation by using placing electrodes on the subject's forehead, to complex neuromuscular feedback during stroke rehabilitation. The EMG signals are acquired from the electrodes applied over or nearby the muscles to be monitored. The electrodes delegates signals to the amplifier unit, usually consisting of high performance differential amplifiers . The usual types of the signal of the interest are in the range of 0.1–2000 mV amplitude, over a bandwidth of about 25–500 Hz.

Scope & Clinical Applications

• Real-time multi-parameter vital signs telemetry (ECG, Heart Rate, SpO2, Temperature, Respiration)
• Low-noise Analog Front-End (AFE) conditioning with active Driven Right Leg (DRL) 50 Hz cancellation
• Digital signal processing in MATLAB: Pan-Tompkins QRS detection, FIR/IIR notch, and Continuous Wavelet Transforms
• Finite element tissue bio-electromagnetics and orthopedic mechanical simulations in COMSOL & ANSYS
• Complete Arduino firmware .INO sketches, circuit schematics, and university dissertation reports