Changes and Updates
There are no changes to announce regarding both the needs statement and the project scope. UN&UP’s requirements remain a vascular phantom for simulating the delivery of a consistent concentration of nanoparticle infusions. Two changes were made to the design specifications in Appendix A, one of which included lowering the maximum voltage to prevent electrical surges from occurring in a Raspberry Pi 400 versus a wall outlet (GDS02). Secondly, SDS01 and SDS02 were more accurately defined once progress was made with coding the firmware. It was determined that the firmware specification will be responsible for the coding of the temperature sensor and flow rate. No software will be developed for the outputs; the temperature data will be output to a log file by the firmware. The only software that will be required will be an existing webcam application to view and record the camera feed.
Verification Plan
SDS01: Infusion delivery monitoring
In order to verify that the infusion can be monitored in a two-plane view, a mirror-camera setup will be utilized to capture the vessels from different angles. A series of photos and videos of the phantom will be taken to verify that everything in the two-plane view can be seen properly.
SDS02: Sensors for correct temperature conditions
To verify the temperature sensor is accurate and responsive, an experiment can be run to verify that the temperature sensor output is correct. In the first experiment, a water-glycerine solution will be heated (starting at a low starting temp) to a near-boiling point using a bunsen burner setup. The system temperature sensor and a common thermometer will be placed in the heating solution. Every five minutes the temperatures of both the known temperature (thermometer) and experimental temperature (sensor) will be recorded until the boiling point is reached. This will verify the accuracy of the sensor.
CDS01: Waterproofing
To verify the waterproofing of the device, water will be run through the device’s tubing for two hours. This exceeds the standard run time by one hour, so it should be more than enough time to verify the tubing system is waterproof.
CDS02: Observation Window
The purpose of the observation window is to be able to visualize the injection of nanoparticles within the phantom veins. The specification will be verified if there is high visibility through the observation window, which can be accomplished by injecting dye into solution flow. If it can be easily distinguished, this specification can be verified.
PDS01: Simulation of Blood
A glycerine-water solution (60:40) has already been proven to be the correct viscosity for mimicking blood properties, so the viscosity does not need to be further verified [1].
PDS02: Heating System
The heating system experiment can be run in conjunction with the temperature sensor test. The water-glycerine solution will be heated in the reservoir configuration. The solution will start at room temperature and be heated to body temperature, mimicking the optimal conditions during a normal run. Throughout the duration of the heating experiment, temperatures from both the temperature sensor and the heating system will be recorded. If the temperature values are near the same values, it can be verified that the heating system works as the specification intends.
PDS03: Pumping System
To determine that the pumping system contains the correct flow rate in order to mimic blood flow in the carotid artery and median cubital/cephalic vein, the amount of water-glycerin solution being transported from the reservoir to the waste system will be calculated. By recording the time it takes for a certain amount of fluid to fully be pumped from the reservoir, the experimental flow rate can be determined. If the experimental flow rate matches the calculated flow rate, the pumping system specification will be verified.
PDS04: Vessel System
One of the most important aspects of the vessel system is that it can transport the fluid and the nanoparticle injections while being transparent to allow for the visibility of the infusion. Therefore, in order to show the visibility of the infusion, a dye will be injected into the vessel. The visibility of the dye will verify that the vessel system allows for visibility and monitoring of the infusion.
PDS05: Catheters
The purpose of the catheter is to inject the nanoparticles through an insertion port on the phantom vessel’s lumen. A test can be completed in order to determine if the nanoparticles can properly be injected through the catheters. This test can be accomplished by injecting a dye with a disposable syringe that can be inserted through the catheter port. Another important feature of the catheter is that it must have a fluid-tight connection to the phantom. The test must also determine the fluid-tight connection–that no dye leaks out in the connection between the catheter port and the phantom.
SFDS01: Firmware
The purpose of the firmware is to primarily support the temperature sensor and flow rate. By verifying that the temperature sensor and flow rate are correct based on the device setup, the firmware can also be verified that it is functioning properly since neither can exist without the other.
SFDS02: Software
While no software is going to be developed within the project, it will be necessary to utilize a software program to view the webcam feed data. If the chosen software supports the webcam at a good framerate that allows for the clear recording of the nanoparticle infusion, the specification will be verified.
GDS02: Surge Protection
In order to achieve surge protection for the device, the electrical current output needs to be within the capacity of the Raspberry Pi unit, which is 5V. Therefore, once the circuitry is completed and all components are communicating properly with the Raspberry Pi, the summed amperage of each component must not exceed 800mA [2]. The surge protection is optimized by limiting the wattage through the Raspberry Pi to 4.0W resulting in zero outages or power resets in the 60-minute runtime.
GDS03: Budget & GDS04: Timeline
All expenses are documented by the client. At the end of the project, the expenses will be compiled to show that the project was completed under budget. Additionally, the project must be completed within the time constraints of the course deadlines and requests of the client, therefore, it does not need any additional specification verification.
Validation
Verification was used to test out the components individually to make sure each part worked properly on its own. The validation looks at the device as a whole and tests the process to prove that the device the group built works for the client’s needs and use. The client, Mike Sabo from UN&UP, gave specific needs and requirements for the device. The validation looks at the device as in two categories for validation: reliability and reproducibility.
When discussing reliability, it is important that the device can be used for a long time without breaking down. Since the device needs to run for at least one hour, testing will be done at different lengths to ensure that the device works well under high stress. Testing from one hour to two hours, each component will be checked that it is functioning properly every fifteen to twenty minutes. If the device does not meet the end goal, it will be determined which part has failed and find a new solution to fix the problem and repeat the testing.
Another critical part of validation is the reproducibility of the device. It is important for the device to be working at each component, but if the device cannot give out consistent data, it has flaws that need to be fixed. Since the device requires consistent delivery of nanoparticles at constant concentration, multiple testing will be done. A color-dyed fluid will be added to the phantom using the catheter port. Through the pump from the reservoir, it should be expected that the fluid added from the port should properly mix to give a consistent color in the tube. This will be done in multiple tries to validate the device gives out consistent results.
FDA Requirements
This product is intended for use in gathering data simultaneously with other vascular phantoms made by the client that are aimed to support a future device produced by UN&UP during the FDA approval process. The goal for the creation of the phantom is to be economical and produce consistent and clinically representative results [3]. Nonetheless, UN&UP should address the technical considerations as part of fulfilling Quality System (QS) requirements since part of the device was made by additive manufacturing. It is likely the vascular phantom is a class I device exempt from the requirement to submit a premarket notification 510(k); however, select class I devices need to maintain procedures to control the devices’ design as per 21 CFR 820.30 to ensure the specified design requirements are met [4]. This is to make certain that 3D printed devices can perform as intended. Whether the device is 510(k) exempt or not, it is important to note the device may not also be exempt from compliance with QS requirements [5].
All in all, it is probable the vascular phantom is a class I device and exempt from a 510 (k) because it will not be used in animal or human clinical trials, endanger the safety or health of any one person, nor contaminate any device that will be used in clinical trials. Due to the aim of the device residing in testing rather than commercial distribution, it is highly possible the device will be 510(k) exempt.
Therefore, UN&UP is not currently in an FDA approval process for the specific product made for testing the nanoparticle infusion in a cephalic vein and carotid artery because it is not being marketed to the public. Regardless, proper documentation of the inspection, measuring, test equipment, and calibration standards should be upheld to maintain the accuracy and fitness of the device as per 21 CFR 820.72 [6].
Current Status
Individual systems of the vascular phantom have been tested separately and proved the proposed ideas were viable; however, a full imitation of how the vascular phantom would work as a whole has not yet been executed. The predominant hindrance delaying a full imitation of the device results from individual systems requiring clarification through further testing. With the inability to bring the systems together, the viability of all current ideas cannot be put to the test. From this point forward, tests are being done to modify the existing viable systems and collect as much user feedback and insight from UN&UP as possible.
The individual systems that are working include the two vessels representing the cephalic vein and the carotid artery, the visualization of the vessels in a two-plane view by a webcam, and the Raspberry Pi hardware displaying the temperature output. Using 3D printed vessels for the vascular phantom, a viable optical clarity to view the nanoparticle injection can be obtained from clear resin and polyacrylic paint pictured in Figure 1. The 3D prints also included the addition of a female Luer lock embedded in the lumen of each vessel to test the viability of attaching the male connector and inserting the catheter through the port. From this proof of concept, an unforeseen risk presented itself in the form of the catheters either being too long or too short for the Luer lock catheter ports.