Kibur Science Spotlight: Self-Expanding Anchors for Stabilizing Percutaneously Implanted Microdevices in Biological Tissues

As implantable microdevices expand their role in diagnostics and treatment, the role of the anchor of these devices is crucial to patient safety and device functionality. Anchors can ensure stability and reduce migration of the microdevice so that it remains in the implant site and doesn’t migrate to other tissues or organs of the patient, and functions properly at the designated site.

In this study, published in the Open Source journal, Microdevices, two anchoring methods were evaluated: a self-expanding nitinol mesh anchor and  self-expanding hydrogel particles contained within pliable netting. The self-expanding nitinol mesh anchor expands mechanically upon release into the target tissue. For the second method, the expandable hydrogel particles are placed in a mesh netting attached to the implantable microdevice and the particles grow and expand when they come in contact with water in tissues.

Implantable microdevices with these two types of anchors, as well as a device with no anchor, were placed into porcine fat, muscle, kidney, and liver tissues. The methods for implantation were similar to fiducial and biopsy marker delivery, and all the devices were left in place for 24 hours prior to force testing and device retrieval. Tensile force testing was performed along the long axis of the microdevice and was performed five times for each device and each tissue.

Following retrieval of the microdevices, it was found that microdevices anchored with the nitinol and the high-absorption hydrogel self-expansion performed better in the force testing compared to non-anchored microdevices. Additionally, the stability of the microdevices with nitinol and high-absorption hydrogel self-expansion anchors increased by a factor of 30-50x compared to the non-anchored microdevices when undergoing dislodgement force testing.

Between the nitinol and high-absorption hydrogel self-expansion anchors, the hydrogel anchors performed better in liver and kidney tissues compared to fat and muscle. The likely explanation behind this is that liver and kidney tissues have higher water content and are denser which may encourage greater hydrogel expansion and stability.

The usage of anchors can greatly improve the stability of a microdevice, and can be implanted into a variety of tissues. As microdevices become more prevalent, it is encouraged that these anchoring methods be further utilized and studied in order to enhance patient safety and reduce migration-related complications.

Read the full Open Source article here: https://www.mdpi.com/2072-666X/12/4/404