Urine Detection: Detection with Dignity - Page 5 of 9

Testing and Evaluation

Prototype 1: Pantyliner with Conductive Thread-based sensor

This figure represents the testing done on the first prototype. Resistance measurements were taken as 10 ml intervals of 0.9% saline solution was poured onto a diaper. From this diagram, one can see that this prototype was valid and could have been made into an appropriate sensor if we had the time and expertise to do so.

Prototype 2: Hydrogel-based RFID sensor with incorporated Copper Nanoparticles (NPs)

No testing was done on this product as our supervisor informed us that the programming, materials, and expertise required would exceed the amount of time that we have to do the project.

Prototype 3: Copper sheet-based sensor with an NFC IC chip, microcontroller, and NFC-compatible reader.

To establish the difference in resistance values in the diaper between dry and wet states, testing was done to ensure these values were different enough to establish a threshold. The setup for our device allowed us to pour a saline solution into the diaper and track the resistance changes.

The resistance values are not at steady state, but rather oscillate in a specific range of resistance values when the diaper was wet. Thus, we can visualize how resistance changes once the diaper is wet to determine a threshold via statistical analysis.

These graphs help illustrate the validity of our prototype that a change in the dielectric constant between the two parallel copper electrodes leads to a change in capacitance upon the introduction of moisture to the diaper (Graph 1) and that a change in capacitance can be measured by the NFC IC chip even when varying the width of the copper electrodes (Graph 2) (Lazaro et al., 2019).

Testing Plan:

This section outlines our planned further testing protocol to ensure device is safe, efficacious, and meets our customer needs and wants specifications.

Biocompatibility Testing

Due to the nature of our product to come into limited duration contact with skin, the FDA requires testing:

In vivo and in vitro
Test for material reaction with skin – cytotoxicity, sensitization, and irritation
Test to ensure radio waves from NFC do not interfere with other essential medical devices (i.e. pacemaker)

Sensor Threshold Testing

Determine the resistance of the sensor when it is not wet to determine a standard for comparing values.
Determine the resistance of the sensor when it is wet, as expected from an incontinence event.
Optimize our sensor for this threshold (difference in resistance between dry vs wet state)
Test to ensure sensor reliably sends signal when any incontinence event has occurred

Comfort Testing

Establish that device is comfortable to wear
Rate comfort on a scale 1-10
Establish that the device does not cause any pressure sores for the patient.

Communication Testing

Ensure that the nurse is notified appropriately after an incontinence episode has occurred.
Ensure that the nurse is notified in a timely manner once the incontinence event has occurred.