Ultrasonic urinary bladder volume sensor

• Main Authors: Carlos, Aldous Kim G., Tomelden, Gerard U., Navarro, Jonavan Emanuel L.
• Format: text
• Language: English
• Published: Animo Repository 1995
• Subjects: Detectors; Digital electronics; Ultrasonics in medicine; Ultrasonic equipment; Bladder > Examination; Electronic instruments, Digital; xx4 Diagnosis, Ultrasonic; Engineering
• Online Access: https://animorepository.dlsu.edu.ph/etd_bachelors/6982
• Institution: De La Salle University

To offer hope of restitution of sensory function to patients suffering from the loss of bladder control, a non-invasive, easy to use device which would indicate a full urinary bladder using ultrasound was designed and constructed. The ultrasonic urinary bladder volume sensor consists of digital and analog circuitry. The device was designed to be used either as a chronic monitor worn by the subject continuously or for periodic checking of the bladder volume. The design was based from the knowledge that as the bladder fills, it expands first in the horizontal plane. Subsequent expansion causes the dome of the bladder to rise above the symphisis pubis. The ultrasonic urinary bladder volume sensor utilizes the ultrasonic attenuation differences between inhomogeneous tissue and homogeneous urine to detect cephalad expansion of the bladder to a specific height above the pelvic floor. The nominal frequency used was 2.25 MHz based on medical standards for ultrasound diagnosis in the lower abdominal area. The transduces is a 13mm single element sector (KB Aerotech). The timing circuitry involves triggering an enable switch to allow the oscillator which is turned to the natural frequency of the transducer to drive it. This uses about 10 ms trigger pulse generated every 5 minutes (more or less). Echoes returning to the transducer are filtered, amplified and converted to its mean absolute value. Since it is sinusoidal in form, its amplitude variation depends on the strength of the echo return or whether or not the posterior bladder wall, indicating a full bladder, has expanded or not. The converted signal is then displayed using a linear LED driver accompanied by a tone signal. The timing circuit also provides a time window which enables the LED display to display the signal received. This time window is adjustable based on the individuals acoustic return echo signal as to when it will return from the posterior bladder wall, indicating a full bladder.