Integrated pH and Strain Sensors Development for Nasogastric Tube Placement Application

This work developed a solution to address the misplacement of nasogastric (NG) tube during tube insertion and feeding. Multiple pH and strain sensors are integrated along the tube for placement confirmation before feeding commenced. This prevented adverse events from occurring due to tube misplacement. A multiple sensors integrated NG tube was proposed to address the clinical needs. The strain sensor measured and determined the shape of the NG tube during insertion. Coupled with the pH sensing capabilities and length of tube insertion information, location of the NG tube can be determined in the patient's body by caregivers before feeding commerce. In this work, strain sensor of 3mm width by 50mm length has been integrated onto the NG tube for bending characterization (bending angle of +/- 80-degree in the x-axis). It is observed that the resistance change in negative angle bending is greater than the positive angle bending for the proposed device structure. Polyaniline (PANI) has been coated on three electrode finishing (gold, silver and carbon) for pH sensing performance evaluation. Gold and carbon based PANI coated electrode has comparable performance within pH 2-8, with sensitivity of -66.7mV/pH and -71.1mV/pH respectively.