IV needle designed to soften upon insertion

Korean researchers have developed an intravenous needle that softens upon insertion, minimising risk of damage to blood vessels and tissues. Described in the journal Nature Biomedical Engineering, the needle remains soft once it has been used, preventing accidental needlestick injuries and unethical reuse.

Intravenous (IV) injection is commonly used to treat patients worldwide as it induces rapid effects and allows treatment through continuous administration of medication by directly injecting drugs into the blood vessel. However, medical IV needles, made of hard materials such as stainless steel or plastic which do not mechanically match the soft biological tissues of the body, can cause critical problems in healthcare settings, from minor tissue damage in the injection sites to serious inflammation. The structure and dexterity of rigid medical IV devices can also result in unethical reuse of needles in order to reduce injection costs, leading to transmission of deadly bloodborne disease infections such as HIV and hepatitis B/C viruses.

Researchers at the Korea Advanced Institute of Science & Technology (KAIST) have now succeeded in developing a so-called Phase-Convertible, Adapting and non-REusable (P-CARE) needle with variable stiffness that can improve patient health and ensure the safety of medical staff. As explained by Associate Professor Jae-Woong Jeong, a lead senior author on the study, “We’ve developed this special needle using advanced materials and micro/nano engineering techniques, and it can solve many global problems related to conventional medical needles used in health care worldwide.”

The new technology is expected to allow patients to move without worrying about pain at the injection site, as it reduces the risk of damage to the wall of the blood vessel as patients receive IV medication. This is possible due to the needle’s stiffness-tuneable characteristics, which will make it soft and flexible upon insertion into the body due to the increased temperature, adapting to the movement of thin-walled vein.

The needle is made up of liquid metal gallium that forms the hollow, mechanical needle frame encapsulated within an ultra-soft silicone material. In its solid state, gallium has sufficient hardness that enables puncturing of soft biological tissues. However, gallium melts when it is exposed to body temperature upon insertion, and changes it into a soft state like the surrounding tissue, enabling stable delivery of the drug without damaging blood vessels. Once used, the needle remains soft even at room temperature due to the supercooling phenomenon of gallium, fundamentally preventing needlestick accidents and reuse problems.

Biocompatibility of the softening IV needle was validated through in vivo studies in mice. The studies showed that implanted needles caused significantly less inflammation relative to standard IV devices of similar size made of metal needles or plastic catheters. The study also confirmed the new needle was able to deliver medications as reliably as commercial injection needles.

The researchers also demonstrated the possibility of embedding a customised ultrathin temperature sensor within the softening IV needle, which can further enhance patients’ wellbeing. The sensor-needle device can be used to monitor the core body temperature, or even detect if there is a fluid leakage during indwelling use, eliminating the need for additional medical tools or procedures.

The researchers believe their transformative IV needle can open new opportunities for a wide range of applications, particularly in clinical set-ups, in terms of redesigning other medical needles and sharp medical tools to reduce muscle tissue injury during indwelling use. And with an estimated 16 billion medical injections administered annually on a global scale, the softening IV needle is expected to become even more valuable in the future.

Image shows the P-CARE needle, which softens upon insertion. Image courtesy of KAIST.