Otoscope Stabilizer Arm - Proximity Sensor Design
Project Overview: Improve upon the electrical system of a medical device stabilizer
Skills Used: Electrical engineering, sensor design
Results: Introduced a new proximity sensor system to detect and indicate distance between the patient and the instrument.
Skills Used: Electrical engineering, sensor design
Results: Introduced a new proximity sensor system to detect and indicate distance between the patient and the instrument.
The Controls Team was to improve upon the existing electrical system of an otoscope stabilizing arm. For this task, we examined the use of distance sensors and accelerometers to supplement the braking system.
The stabilizer arm was designed so that an ear doctor can have an otoscope externally supported near a patient while the doctor is free to use his/her hands for other instruments during the otoscopy. The existing otoscope stabilizer had no sensors to receive feedback from its surroundings. The arm had a magnetic braking system that deactivated upon the press of a button located on the otoscope holder.
In our Sensors Team, I designed a proximity sensor system that provided visual and auditory feedback to indicate the otoscope’s relative position to an object.
The stabilizer arm was designed so that an ear doctor can have an otoscope externally supported near a patient while the doctor is free to use his/her hands for other instruments during the otoscopy. The existing otoscope stabilizer had no sensors to receive feedback from its surroundings. The arm had a magnetic braking system that deactivated upon the press of a button located on the otoscope holder.
In our Sensors Team, I designed a proximity sensor system that provided visual and auditory feedback to indicate the otoscope’s relative position to an object.
As an initial design, the Parallax PING))) ultrasonic sensor was chosen. The idea came from the use of sonar as a distance sensing technique. The PING))) sensor was easy to interface to an Arduino board with one power, one ground, and one signal pin. It was also affordably priced at $30. This option was later discarded because the minimum end of its effective range (3 cm to 3 m) did not suffice our application. There were also concerns that the ultrasonic pulses would interfere with measurements of the ear drum.
The next option was the SparkFun ToF Range Finder Sensor. The sensing range was much shorter than the PING))) as it operated between 0 cm and 10 cm with an accuracy within 2 mm. At a similar price point of $25, the sensor was much thinner and did not create potential interferences with ear drum measurements. It was mounted on right side of the clear acrylic handle face.
The Range Finder distance data was coupled with Arduino code that activated a set of 3 LEDs and a beeping device mounted on the power box. These LEDs flashed red, yellow, or green depending on how far the device was from a solid object. The goal was to provide visual feedback to the user. Similarly, the beeper provided auditory feedback based on relative distance.
The Range Finder distance data was coupled with Arduino code that activated a set of 3 LEDs and a beeping device mounted on the power box. These LEDs flashed red, yellow, or green depending on how far the device was from a solid object. The goal was to provide visual feedback to the user. Similarly, the beeper provided auditory feedback based on relative distance.
As the user moved the arm towards the patient’s head, the proximity sensor sent a signal back to the Arduino. It calculated the velocity of the movement and reported the distance, velocity, and ambient light level back to the user. A series of LEDs lit up based on the relative distance to the patient. A separate beeper emitted pulses of sound as a function of velocity. If the user approached the head too quickly, it emitted quick, short beeps. Slower velocities produced pulses with greater delay. The proximity sensor effectively replaced the existing system’s accelerometer. Future designs would investigate different placements of the sensors and feedback systems to better provide a pleasant exam experience for both patient and physician.
