Finger Pressure Sensor

Finger Pressure Sensor

Spring 2018  MAE 156B Senior Design Project

University of California, San Diego

Euan Tan,  Kyle Gillespie, John Tayag, Michael Bagherpour 

Sponsored by 

Michael A. Chang, MD

Gastroenterologist

Assistant Professor of Medicine

        Final design prototype with surgical glove on top of it.                                       Calibration procedure using a load cell                                Initial 3D printed test bed for the pressure sensor

Background:

Endoscopies have allowed physicians to examine the inner cavity of patient's digestive system using a long, flexible tube with a small camera at the tip. Gastroenterologists, doctors who perform this procedure, are able to diagnose and treat upper digestive conditions that affect the stomach, esophagus, and the duodenum. However, over the past 20 years, gastroenterologists have experienced a sharp increased in the frequency of endoscopic procedures. This procedure now covers 40-60% of their clinical hours. Typical endoscopic procedures run for 10- 5 minutes but could run for as long as 2 hours to complete. Injuries are becoming more common, largely stemming from uncomfortable wrist angles and excessive pinch forces causing immense strain and fatigue. 20% of these physicians have taken off work in order to recover from these injuries. 

Objective:

We are interested in creating a device that will:

• •  Measure the pinch forces exerted by the user for each hand.

  •  Calculate wrist angles of the user's individual arms during endoscopic procedures.

  •  Train doctors through audio, haptic, or visual feedback to prevent injurious use.

  •  Communicate the data in real time to a separate monitor. 

  •  Save the data to a back-up file for offline use. 

Final Design Concept:

• Our final design consists of three Tactilus finger pressure sensors on each hand located in pockets at the tips of the thumb, index and middle finger to measure pinch forces. These sensors are calibrated to have a threshold of 10N, a force within the range of causing repetitive strain injury. A calibration rig is created to convert the unit-less readings of the Tactilus into Newtons. There will be two IMU (Inertial Measurement Units), one located on the back of the hand, and the other located on the upper forearm that will calculate the wrist angles of the arm from the neutral state. These sensors will relay information to a wireless electronic module through bluetooth which is also located on the upper forearm. This wireless module communicates to a Raspberry pi in real time. The Raspberry pi creates its own Wi-Fi server and the user logs into this webpage to view the live graph for analysis. A haptic feedback buzzer is also integrated into the back of the arm and vibrates when the user is approaching the threshold force according to the sensors.