Depth Controlled Needle Gauge

Medical Device Design I

The Variable Depth-Controlled Needle, or VDC, was my first biomedical need-based design project for the Medical Device Design I class at the University of Cincinnati. This device allows the clinician to set a maximum needle depth for aspirating peritonsillar abscesses in the throat, as well as other regions of the body where over-injection would cause further complications. This idea came about because clinicians are often seen taking the caps off of needles, cutting part of the caps off, then recapping the needles. Recapping is against protocol and can result in sticking, breaking the clean barrier, and/or contaminating the procedure. This device removed the need to cut the cap and then place it back over the needle. Although it was originally designed for aspiration, the VDC clearly possessed alternate profitable uses in general medicine, such as intramuscular, intradermal, and subcutaneous injections.


The images below were all "out of the box" concepts to try and control how much of the needle was exposed. Although they accomplished the task, they either hindered visibility, made it diffucult to manuever the needle, or would be very difficult to assemble.


The images in this section are the first iteration of the concept chosen to be the best using both a pugh matrix and clinician interview data.


This final section shows the refined final concepts and the overall output of the entire process. Depth setting indicators and low density rubber were added to make the concept more feasible. Though this device remained within the cost margins, there is still rrom for improvement; namely, reducing the number of components and assembly steps.


Below is a video showing how the device works to set the maximum depth for the injection of the needle. It has three basic steps: Setting the depth, Squeezing the clamp, and Removing the Shield. The clamp uses a cable tie fastening system which crimps around the body of the needle. Rubber on the inner portion of the two halves of the clamp keeps it in place during injection procedures. The clamp will stay in place under the typical quantities of force for aspiration procedures, as well as any other general surface injections. In addition to physically preventing over-injection, the clamp is also able to be used as a highly visible depth indicator to let the clinician know how much of the needle has been injected during a procedure.

Ultimately, this course gave me the necessary skills for creating a design master file, choosing final concept designs, and building basic functional prototypes. Throughout the process of concept creation, my team revised design requirements and product specifications until we arrived at a design that would physically work the best and stay within the provided cost margins.