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Capillary Biomedical Automation Project
Capillary Biomedical is an emerging startup developing devices for diabetes management. The Capillary Biomedical Automation Project aims to improve and automate the current manufacturing process for Capillary Biomedical's insulin delivery devices. See the other pages for more details.
Project Background
Capillary Biomedical has designed a machine to heat stake polypropylene disks to adhesive webbing so that users can attach a catheter to deliver insulin easily. The polypropylene disk is shown to the right. The process to produce these components consists of a polypropylene disk being placed in the nest of the machine, located at the base. An adhesive webbing is then aligned on top and a heating element presses the two components together to melt the polypropylene disk until it adheres to the adhesive webbing.
Image Courtesy of Capillary Biomedical
Objectives
The current manufacturing process for Capillary Biomedical's insulin delivery devices is completely manual. The ultimate goal for our project is to lessen production time and increase efficiency through automation. Below are the objectives that we aim to complete to achieve the ultimate project goal:
Implement safety parameters to prevent operator injury.
Improve robustness of machine so that multiple units can be produced without need for machine repair.
Create user-friendly interface so that there is less possibility for operator error.
Partially or fully automate process to increase production rate.
Proposed Solutions
In an effort to achieve these goals in our final design, the following are possible solutions currently proposed by our team:
Implement sensors connected to user interface to measure and sense the presence of polypropylene disk.
Introduce metal rod fixture in bottom metal plate to align adhesive patch and plastic component with greater ease.
Implement method to unwind adhesive roll for placement onto bottom metal plate.
Encase entire machine assembly behind a shield (similar to a CNC machine) and only allow machine to operate if shield is closed.
Design
Our preliminary design features a linear actuator that drives the nest up and down. Once the nest has reached the heating element, it will consistently apply 90 lbs of force for 10 seconds. Implementing the linear actuator will eliminate the need for a torque lever and combine the nest movement and heat staking into one process. In the left figure below, the linear actuator feature is shown. The nest rests on top of the linear actuator and the linear actuator rests on top of a housing compartment.
The final design uses the same layout as the original heat staking system with the heating element descending from above and pressing into the nest at the base. However, the heating element is being controlled by a linear actuator that is connected to an Arduino Mega 2560. The Arduino controls the speed of the linear actuator through Pulse Width Modulation (PWM) and feedback from load cell sensors located below the nest. This allows for complete and precise control over the amount of time the heat staking occurs and force being applied to the polypropylene disk and adhesive patch. The accuracy obtained from the Arduino driven system improves the quality and repeatability of the heat staking process.
Preliminary Design Final Design Redesigned Horns
Current diabetes management methods are inconvenient and invasive. Capillary Biomedical's goal is to not only simplify the insulin delivery process but to manufacture devices that will allow for the attachment of an insulin infusion catheter for a longer period of time than the current usage time of two to three days. In doing so, insulin pump users avoid excessive needle puncture wounds.
Another new feature in our proposed design is a redesigned horn component shown in the right picture above. The horns, which resemble a stamp, are heated by two cartridge heaters so that they can melt the strategically placed energy directors on the polypropylene disk to the adhesive webbing. The original design of the machine experienced a large temperature tolerance of +/-20 degrees Celsius in the heating element. This temperature is obtained through a thermocouple attached to a plate located above the horns. By combining the horns and the plate into one component, the temperature readings will be more accurate.
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