Advanced robotic prosthesis are capable of performing complex movements, and equipped with multiple proprioceptive and exteroceptive sensors and embedded controllers for implementing automatic grasp control and for potentially delivering sensory feedback to the amputee. We developed a non-obstructive regenerative multielectrode interface (REMI), placed between the transected ends of an end-to- end repaired nerve. A further development on the REMI was the use of growth factors in a Y-shape conduit for modality-specific neural interfacing in the PNS. We reported a miniaturized wireless 16-electrode array for peripheral nerve stimulation, which worked reliably continuously in vivo for more than 14 months. Subsequently, we tested a sub-millimeter wireless stimulator and recently demonstrated that this device can be attached to commercial nerve cuff electrodes for wireless neural stimulation. Since commercial cuff electrodes are made with relatively thick silicone conduits, we also reported the fabrication of 16-electrode arrays using a thin film softening polymers that are cause significantly less fibrosis compared to silicone cuff electrodes.
Neurotrophic factors (NTF) such as NGF, BDNF, and NT-3, as well as GDNF, play an important role in axonal regeneration. To provide sustained three-dimensional molecular gradients and extracellular matrix support we developed a method capable of establishing sustained 3D NTF gradients in the collagen-filled lumen of multi-luminal nerve guides and showed that NGF gradient increased axonal length. This device was patented and licensed to Tissue Gen Inc. We recently demonstrated that PTN and GDNF synergistically stimulate nerve regeneration across 3 and 4 cm long-gap injuries.
We have been interested in developing testing new materials that can improve the conductivity and safety of peripheral nerve interfaces. We first reported the use of carbon nanotubes as material for neural stimulation/recording. More recently we showed that platinized graphene fibers have significantly lower impedance and increased charge injection capacity compared to Pt electrodes. We have also been interested in developing new medical applications for neural interfacing. We have shown that stimulation of somatic nerve fascicles can effectively reduce the mean arterial pressure in genetically hypertense rats, and that stimulation of motor nerves controlling individual pelvic floor muscles can be used as a treatment for stress urinary incontinence.
During development axons are guided to their targets via membrane bound and secreted molecular cues, which can be either attractive or repulsive. We uncovered the role of NT-3 in proper targeting of thalamic neurons projecting to the primary sensory cortex, defined the role of Klf7 in the regulation of nociceptive neuron development, and discovered that Ephrin B-3 plays a critical developmental role in the proper targeting of axonal projections from the primary motor cortex to the ventral motor neurons in the spinal cord. We then discovered that EB-3 is upregulated in oligodendrocytes early postnatally and reported for the first time that this molecule is a myelin-associated inhibitor in the adult spinal cord. We uncovered the role of the Ephrin ligands in guiding the migration of CA-3 hippocampal neurons from their birth site in the sub-ventricular zone, to their final destination in the ventral hippocampus.
Scoliosis corrective surgery requires the application of multidirectional stress forces to the spinal cord, including those of distraction. We have designed an innovative device that relies on intervertebral grip fixation and computer controlled linear actuators to induce bidirectional distraction injuries to the spine. We have shown that NGF can overcome the inhibitory nature of the CNS, and have shown that Riluzole has neurprotective effect in an animal model of atraumatic spine distraction injury
Scoliosis corrective surgery requires the application of multidirectional stress forces to the spinal cord, including those of distraction. We have designed an innovative device that relies on intervertebral grip fixation and computer controlled linear actuators to induce bidirectional distraction injuries to the spine. We have shown that NGF can overcome the inhibitory nature of the CNS, and have shown that Riluzole has neurprotective effect in an animal model of atraumatic spine distraction injury
