Welcome to Bioelectronics Group!

We are an enthusiastic and diverse group of materials scientists, electrical engineers, bioengineers, and neuroscientists working at the interface between synthetic electronics and the nervous system. We use a variety of fabrication methods ranging from fiber drawing and CMOS-compatible processing to organic and organo-metallic synthesis to create materials and devices capable of addressing the complexity of signaling modalities found in neural circuits. We are interested in developing multifunctional flexible and stretchable devices to enable simultaneous recording and modulation of neural activity in the brain, spinal cord and peripheral nervous system. We also investigate magnetic nanomaterials to impart sensitivity of neurons to externally applied magnetic fields. We apply our neural interface tools to studies of brain circuits implicated in neurological and psychiatric conditions including depression, post-traumatic stress, and Parkinson’s disease. Our spinal cord and peripheral nerve interfaces are aimed at studies of nerve repair following traumatic injury or degeneration.

Flexible Fiber-based Neural probes

Minimally invasive neural probes are very important in understanding the mechanism of debilitating neurological conditions, both in the central and peripheral nervous systems, and to enable treatment of these conditions. Currently available neural probes, however, are limited in their use in the long term by deterioration of the electrode-tissue interface supposedly caused by glial scarring and neuronal death around the probe. We fabricate flexible probes that could help to decrease tissue response to the probe as well as increasing the ability to implant the probes in hard to reach places.

To fabricate this kind of probes we apply a thermal drawing process. To this end, we start with a template (~2.5-4 cm in diameter), and apply controlled heat and stress to obtain fibers hundreds of meters long with preserved cross-sectional geometry, but reduced in diameter to the micrometer scale. This way, the recording surface of the electrodes can be tuned down to <1 μm, while maintaining controlled pitch. Different materials can be incorporated that result in different functionalities of the probes or to change the geometry of the device after the drawing process. The probes we fabricate are tested to confirm their usability in vivo.

Tissue Engineering

Injuries to the peripheral nervous system (PNS) affect a broad population globally and due to limited treatment options, full recovery is limited. In the United States alone, there are over 360,000 peripheral nervous system injuries every year. Of these injuries, 200,000 repairs are preformed, however only 40% of patients will regain normal function. Hence, there is a high demand for clinically relevant strategies to aid axonal regeneration and return patients to physiological function. While autografts are the gold standard for surgical repair, donor tissue is limited and results in secondary co-morbidity. In the case of a complete nerve transection with large gap distances (greater than 4 cm) functional recovery becomes highly unlikely even with surgical intervention. Therefore, clinically relevant synthetic nerve guidance channels are in high demand.

Our proposed solution is to utilize the thermal drawing process (TDP) to fabricate flexible, biocompatible polymer-based neural electronic scaffolds (NELS) with inner diameters 20-250 µm and lengths up to tens of centimeters. We take advantage of TDP’s fine control of variable dimensions and our ability to include topographical cues, polymer electrodes, and waveguides to promote nerve regeneration through a multifaceted approach. Furthermore, through the inclusion of electrodes in our guidance channels we are capable of monitoring regeneration in vivo. We are evaluating NELS in vitro with a whole dorsal root ganglia (DRG) culture system as well as a sciatic transection model in vivo. In addition to developing new methods for fabricating nerve guidance channels, we are working to explore the regenerative potential of optogenetics.

Nanomagnetic Medicine

An emerging class of bioelectronics medicines based on minimally-invasive and wireless methods may be of clinical relevance for modulating electrical signals in deep brain structures. A potential platform is the conversion of alternating magnetic fields (AMFs) into a biological stimulus accomplished by magnetic nanoparticles (MNPs) that dissipate heat via hysteretic power loss. AMFs in the low radiofrequency regime can penetrate deep into the body with no significant attenuation due to the low magnetic susceptibility of biological tissue. Heat-mediated actuation of a thermally-responsive cation channel TRPV1 from the transient receptor potential vanilloid family enables control over cellular functions ranging from cell-membrane depolarization to gene expression.

To explore whether rapid and reversible neuronal activation with AMFs can be achieved, we are developing intracellular calcium ion control schemes that rely on an optimized magnetic nanoparticle set that are stable in physiological milieu. Utilizing a dynamic hysteresis model to guide us in the synthesis of single-crystalline and monodisperse ferrites, we are investigating whether heat dissipation optimized at different AMF driving conditions can evoke neuronal activity in vitro and in vivo. The same principles are also being extended to control the conformational dynamics of protein aggregates, which has implications in the treatment of neurological disorders such as Alzheimer’s.