ULTRASOUND AIR BUBBLE DETECTOR FOR MOVING BLOOD (ARTIFICIAL KIDNEY APPLICATION)

Detection of air bubble using detector is important to reduce the presence of bubbles
that may affect the entire body of human. For a hemodialysis machine, if it is
operated without a blood pump then the blood circuit would be under positive
pressure and allow air entry into the circuit. Multiorgan dysfunction can occur as a
consequence of air entering into the blood circulation and giving rise to the
appearance of micro emboli. Early sensors were photo-optical, but their sensitivities
were limited and the ambient light subjected them to give false alarm. Nowadays,
most detectors use ultrasound and its principle of operation is based on the
measurements of attenuation, waveform and velocity. But, it could not detect size of
air bubbles below 850f.J.m. To improve the sensitivity of the device, a simulation
study using Multsim is conducted. Basically, this study is more about the principle of
the air sensor and its mechanism. The study consists of theoretical background,
simulation and its implementation. It starts with reading and also collecting the
information from the journals, articles and books. The simulation is done then a
prototype is constructed. In simulation, it is able to detect air bubbles with size less
than 8501J.m, which is 680f.J.m. This report consists of five chapters. Chapter 1
consists of background of study, problem statement and the objectives. Chapter 2
consists of a literature review and overview of the project while methodology part is
stated in Chapter 3. The results and discussions are in Chapter 4. The study is ended
up with conclusion and recommendation in Chapter 5.