Shape Memory Polymer-Based Insertable Electrode Array Towards Minimally Invasive Subdural Implantation

Abstract

Minimally invasive implantation of subdural electrodes can dramatically benefit the patients with various neurological diseases. In modern clinical practice, the implantation procedure of the electrode arrays remains traumatic for patients and increases postoperative infection risk. Here we report a design and insertion technique of thermally activated shape-memory polymer-based electrode array that can recover up to ten times length deformation. The compressed four-centimeter wide array can be easily packed into a three-millimeter diameter tube and subsequently deployed thought five-millimeter opening in a restricted space between a brain phantom and a simulated skull. The mechanical properties of the developed array are comparable to the materials traditionally employed for the purpose, and the electrical and signal recording properties are preserved after shape deformation and recovery. Additionally, the array is biocompatible and exhibits conformability to a curvy brain surface. The results demonstrate that insertion of the electrode array through a small hole into a restricted space similar to subdural cavity is possible, which may inspire future solution of minimal invasive implantation for patients suffering from epilepsy, amyotrophic lateral sclerosis or tetraplegia.

Neuromuscular implants: Interfacing with skeletal muscle for improved clinical translation of prosthetic limbs

“…(A) Kirigami electrodes combine flexible polyimide material with a novel flexible design that allows them to wrap around a muscle and withstand mechanical strain during contraction. 66,67 The polymers naturally unfold at 37 C to match the contours of their target tissue. circumvent many of the problems caused by skin, making them a suitable alternative for improved clinical implementation and longterm use.…”

“…Figures adapted from Salminger et al and Pasquina et al 62,63 (D) Shape memory polymers can “self‐climb” around tissue or “self‐unfold” after injection through a small needle. Left and right figures adapted from Zhang et al and Kravtcova et al, respectively 66,67 . The polymers naturally unfold at 37°C to match the contours of their target tissue.…”

“…Similarly, self‐unfolding or unraveling polymers have been fabricated for minimally invasive implantation of retinal or cortical electrodes at physiological temperature (37°C) (Figure 3D). 67 Self‐unfolding electrodes are an excellent candidate for epimysial electrodes which need to conform to a variety of different muscle sizes and physiologies. Intramuscular implantation can also be simplified with shape memory polymers: a flexible electrode is ideal post‐implantation since it will be exposed to high degree of movement within the muscle, but a more rigid electrode is ideal for insertion.…”