Verification and Validation processes will be conducted in the future to test to see if our device outputs align with our inputs and if our device meets our user needs that we outlined in our Traceability Matrix.

Verification

Verification processes aim to see if our outputs align with our inputs. We plan to do the following to see if our design inputs are met:

Customer Requirements:

  • Distribute the average squeezing force of 14.7 N, the force needed to be exerted when dispensing one drop of solution, by increasing the surface area that interfaces with the hand by means of an attachment that holds the bottle.
    • Carry out force distribution tests using pressure-sensitive films that evaluate how evenly force is applied across the relevant surface area of the palm.
  • The design must account for mechanical reinforcement at stress concentration points to prevent fracture if users apply excess force or squeeze at off-axis angles.
    • Determine maximum stress and working stress and find the ratio between the two to confirm a safety factor of 2 or above has been achieved.
  • The eyedrop bottle will be placed inside the aforementioned attachment, increasing the total surface area to allow for interfacing with the entire palm instead of a select few fingers.
    • Conduct internal pressure testing using pressure-sensitive films that determine if there exist localized pinch points.
  • The attachment will concentrate the force applied by the user at specific pressure points on the inner walls of the attachment to transmit squeeze force to the bottle
    • Conduct internal pressure testing using pressure-sensitive films that determine if there exist localized pinch points.
  • The attachment to the tip of the bottle should be slightly compressible and have a general elliptical shape that fits a variety of eye shapes.
    • Carry out compression tests and measure attachment dimensions to ensure they are appropriate for a comfortable fit around the average eye shape.
  • Able to attach to eyedrop bottles ranging in size from 5 to 20 mL by using a flexible material (shore hardness ~30 A) that can conform to various bottle sizes and then return to the original form after use
    • Physically test the fit of the squeezing component with the 15mL bottle by slotting bottle inside the cavity. Ensure that bottle does not fall out and installation and removal are not challenging.

Product Performance Requirements:

  • Device can fit in the palm of the user’s hand. Average hand sizes for males and females range from 7.4 – 8.3 cm across the widest part of the user’s palm\
    • Use calipers to measure the dimensions of the final prototype. Confirm that the width is ideally between 7.0 – 8.0 cm. 
  • Use a material like tin-cured silicone rubber that has a shore hardness value as close as possible to the ideal value of 30 A.
    • Measure Shore hardness using a durometer to confirm it meets 30 ± 5 A.
  • Use a rigid and non-slip material like PLA5
    • Check material specifications of PLA to seee if properties match desired inputs
  • The device should be lightweight, around 50 grams, to allow for minimal strain on hand while holding up.
    • Measure the total mass using a digital scale
  • Static Friction Coefficient of material should be 0.6-0.8 minimum to prevent slippage from hand.
    • Test friction coefficient using standard tribometer methods to confirm coefficient is within 0.6 –  0.8 range
  • The 3D printed design of the positioning attachment should be filleted to contain only smooth surfaces with no sharp angles.
    • Visual inspection of CAD prototype to confirm there are no sharp transitions
  • Has attachment around the top of the device that is held against the user’s face to keep the bottle steady and positioned to drop the drug within a radius of 10mm of the iris. The attachment being in contact with the face enhances the stability with which the bottle can be held to improve alignment
    • Simulate drop trajectory to ensure it consistently lands within the 10mm target area
  • Has magnets embedded in the structures of both the squeezing and positioning components. Magnet should be incorporated in both the components as they are being cast in the molding and casting process
    • Measure and ensure that the force required to separate and join the components is < 5N. Check for correct alignment when components are joined. 

Sterilization:

  • Use of materials like tin-cured silicone and PLA that can be wiped down with a disinfecting wipe.
    • Perform wipe-down tests and verify that materials do not degrade or retain residues after cleaning

Safety:

  • Risk Analysis and Evaluation of overall residual risk will be carried out, following the guidelines outlined in ISO 14971, Sections 5.1 to Section 8.
    • Conduct risk analysis review according to ISO 14971
  • Eyedrop bottle tip is at least 12mm above the user’s eye when positioning device is planted on face to circumvent the blink reflex.
    • Measure final 3D printed piece with sample eye drop bottle to verify the ideal height

Validation

Validation processes aim to see if the user needs are met with the device. We plan to do the following to see if all of our user needs are met:

Customer Requirements:

  1. Reduce pressure (force per area) exerted on user’s hands when using eyedropper
  2. Attachment that fits the eye-area of an average person
  3. Support different eye drop bottle shapes and standards
  • Complete User Testing
    • Ask users if they experience more or less hand strain when squeezing eyedrop bottles with or without the device.
    • Ask users to assess whether the additional pressure points improve the ease and effectiveness of squeezing the eyedrop bottle.
    • Ask individuals of varying eye shapes and sizes to confirm that the attachment comfortably fits around the eye and provides a secure interface during use.
    • Ask users on ease of use and perceived fit with a 15mL bottle in the device and collect feedback
  • Conduct a study
    • Instruct users to apply as much force as they physically can to the product and observe if any damage occurs. 

Product Performance Requirements:

  1. Appropriate size that strikes a balance between portability and ease of use
  2. Material for the attachment to the body of the bottle must aid in squeezing motion
  3. Material for the second attachment to the tip of the bottle must allow for stable positioning of the bottle for efficient dispensing of eye drops into the eye
  4. Optimize comfort for users’ face and hands
  5. Positions eye drop bottle optimally to allow for eyedrop to directly enter the users’ eye without spillage
  6. The squeezing and positioning components must be easily joined into a single device and just as easily separated into two distinct parts.
  • Complete User Testing
    • Collect feedback on portability, heaviness and ease of use.
    • Confirm ease of squeezing and comfort during use
    • Ask users if the bottle remains stable when in position
    • Collect feedback on comfort and possible strain with extended use
    • Ask users if the device does not slip during normal use
    • Ask users to confirm or deny comfort in contact areas; no reports of discomfort due to sharp or angular surfaces during use
    • Ask users if the device allows for accurate drop placement into the eye with minimal or no spillage
    • Ask users if they can easily separate the components without excessive force

Sterilization:

  1. Utilization of a material that does not easily accumulate dust or grime
  • Complete User Testing
    • Users report easy cleaning experience and no noticeable grime buildup after multiple uses

Safety:

  1. Usage of device does not lead to any accidental or preventable injuries
  2. Maintains a safe distance between eyeball and tip of the eyedrop bottle to circumvent the blink reflex
  • Complete User Testing
    • User feedback confirms that the device is safe when used as instructed
    • Ensure that the tip of the eyedrop bottle is comfortably far enough from the user’s eye