Background
Sensal Health is the brainchild of President and Co-founder Deepak Sirdeshmukh. The Chapel Hill, NC-based medical startup specializes in medication adherence monitoring, creating products and applications that remind patients to take their medication, determine whether they have, and record the data in a database accessible to medical professionals.
Porticos collaborated with Sensal on two new product designs: the Cap Tube and Medication Dock. The Dock measures pill bottles while the Cap attaches to ointment tubes. Both products use small, precise load cells which act as tiny scales, recording the dispenser’s weight before and after a patient takes their medication. They record the measured changes in weight and compare them to each patient’s prescribed dosage. This information aids doctors in more accurately assessing their treatment plans.
Challenges
The Dock project started shortly after the Cap project and borrows aspects of its predecessor’s design. At its core, the load cell and measurement code are the same: instead of using capacitive sensing to determining when a tube screws onto the cap, the dock uses Near Field Communication (NFC) to detect a tag on the bottom of a pill bottle.
The unit’s tag includes a unique ID number that corresponds to a specific medication in their portal. The NFC and load cell readings help determine when a bottle is on the scale and assign the dosage to that medication. The Dock includes a display not present on the Cap.
An engineering firm in Houston, TX developed an initial proof-of-concept with many issues and a list of requested improvements. The primary challenges were:
- Power consumption
- Ointment tube detection
- Weight measurement consistency
- Product fragility
The latter of these posed the greatest challenge because load cells with the required accuracy (+/-0.1g) and repeatability (+/-.05g) are inherently ultrasensitive and fragile: surface vibrations affect weight measurements and normal handling can cause permanent damage, crippling performance.
Outcomes
Porticos collaborated with Sensal’s technical staff to develop filtering algorithms that eliminated inaccurate measurements because of environmental factors. We also developed a mechanical architecture to protect the load cell from abuse during normal operation. Finally, we developed a capacitive sensing circuit and algorithms to identify the presence or absence of the tube with >99% accuracy.
Porticos delivered five functional pilot units for their partners to evaluate. Sensal has used the units for several months with no reduction in performance.
