Next Generation Needle Technology: The Comfort Entry Needle

Introduction

This project was motivated by my observation of the emotional and physical distress caused by needle-based procedures. Repeated exposure to injections, especially those requiring larger-bore needles, can contribute to lasting anxiety and avoidance. This experience made me realize how needle-related pain is one of the most dismissed problems in healthcare, and if no one was going to fix this, I would try.

Existing solutions, such as microneedle-based systems (Nanopass), have demonstrated significant reductions in pain by minimizing tissue deformation. However, research shows that these designs are limited in their ability to deliver viscous formulations, such as protein (e.g., Humira) and nutrient-based therapies, due to reduced flow capacity. As a result, conventional larger-gauge needles remain necessary in many clinical scenarios, where discomfort is often greatest.

From an engineering perspective, this reveals a fundamental constraint: smaller needle radii require less force to pierce the skin, but allow less medicine to flow through, while larger radii allow for more medicine to flow through, yet require more force to pierce the skin, therefore activating more nociceptors and causing more pain for the patient. This tradeoff (FIG.1) has not been effectively resolved in current needle designs.

This project addresses that gap by exploring whether a dual-stage mechanism can decouple puncture and fluid delivery, enabling both reduced insertion force and maintained flow efficiency.

To support further development, a patent was filed to protect the intellectual property associated with this design while enabling continued future application.

The Comfort Entry Needle resolves the trade-off between insertion force and flow rate by using two components instead of a single needle. A microneedle with a smaller radius extends past a larger bore needle to pierce the skin, reducing insertion force and creating a pathway. The larger needle then follows behind to deliver fluid efficiently. Once both needles are inserted, the microneedle retracts using a thumb slider controlled by the user and locks into a guide slot along the hub walls, creating a “snap” that prevents fluid leakage. The larger needle is then able to maintain efficient flow according to Poiseuille’s Law, where flow rate is proportional to the fourth power of radius.

To develop this mechanism into a functional design, four prototypes (V0–V3) were created, with Version 0 serving as an initial feasibility model used to explore integration of the mechanism within the design. At this stage, the concept was considered highly challenging and was often regarded as impractical by professionals consulted. Version 3 was the final optimized design.

Testing was conducted using silicone skin pads, a force gauge, thin plastic tubes, and fluid (saline and water) to evaluate insertion force, placement accuracy, flow rate, and ergonomics. A thin silicone pad was placed over fluid-filled tubing to simulate realistic targeting conditions. Across 20-plus trials, the final design achieved a 57 percent reduction in insertion force while maintaining flow rate and improving placement accuracy. These results demonstrate that needle performance can be significantly improved through geometric redesign without sacrificing efficiency.

Testing Overview

A minimum of 20 trials were conducted. A standard 18-gauge needle and the Comfort Entry Needle were used for all tests.

Insertion Force

A silicone skin pad with a sponge backing and a force gauge was used. Both needles were inserted at a 90-degree angle with the force gauge applied to the hub. Across 21 trials, the standard 18-gauge needle averaged 0.7 N, while the Comfort Entry Needle averaged 0.3 N, representing a 57% reduction. This demonstrates reduced tissue deformation and nociceptor activation.

Flow Rate

The standard needle achieved 0.35 s/mL, while the Comfort Entry Needle achieved 0.31 s/mL. These values were considered comparable. Combined with the insertion force results, this provides validation that pain can be reduced without sacrificing flow rate.

First Attempt Placement Success

A fluid-filled tube was covered with a silicone skin pad. The goal was to withdraw fluid in a single insertion. The standard needle achieved a 60% success rate, while the Comfort Entry Needle achieved 100%. This demonstrates improved placement accuracy and potential for IV applications.

Ergonomics

Volunteers performed one insertion to establish baseline time, followed by 20 repetitions. The time and accuracy of the 21st attempt were recorded, along with fatigue and confidence ratings. The standard needle had faster baseline times and slightly better grip confidence, while the Comfort Entry Needle resulted in lower fatigue and higher final placement success, indicating improved performance over repeated use.

The results demonstrate that needle comfort can be significantly improved through simple geometric redesign without sacrificing functional performance. The Comfort Entry Needle achieved a 57% reduction in insertion force, indicating reduced tissue deformation and potential pain reduction, while maintaining a flow rate comparable to a standard needle.

Additionally, the design showed improved first-attempt placement accuracy and was rated as less fatiguing during repeated use, suggesting enhanced control and usability over time. These outcomes confirm that the dual-stage mechanism effectively separates puncture and fluid delivery, allowing both to be optimized independently.

From an engineering perspective, this provides validation that the traditional force–flow trade-off can be resolved in this application through functional separation rather than compromise. The results indicate that both comfort and efficiency can be improved simultaneously, which is not achieved in conventional single-needle designs.

Overall, the findings are in strong agreement with the initial hypothesis and fully meet the defined design criteria. They support the conclusion that this approach has practical potential for improving needle performance in real-world medical applications, particularly in scenarios involving repeated use or viscous fluid delivery.

Future Research

Future work should focus on improving ergonomic performance and expanding testing conditions. While the prototype reduced insertion force and maintained flow rate, user feedback showed variability in grip, confidence, and disposal efficiency. Additional testing across different insertion angles, flow conditions, and user experiences would strengthen the understanding of performance. Future validation in professional laboratory settings with trained medical personnel would provide more realistic results and support further development toward clinical application.

(FIG. 7, A, B, C, D, are sketches of a micro laser diode located on top of a regular needle)

Acknowledgements

I would like to express my deepest appreciation to my committee.

This project was designed and executed independently over the course of the year. I am grateful to several individuals who provided support that made the work possible.

I would like to thank my mother for financial support, for purchasing materials, and for covering the costs associated with patent filing through the United States Patent and Trademark Office.

I appreciate the time given by my volunteers who participated in user testing.

I also thank Mr. Zhang for generously providing access to his 3D printer and producing prototype parts. His assistance was limited to 3D printing fabrication and did not involve design or engineering.

Finally, I acknowledge my school for providing a place to think, plan, and occasionally use workspace resources during the development of this project.

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