Focused Epicranial Brain Stimulation by Spatial Sculpting of Pulsed Electric Fields Using High Density Electrode Arrays.

Transcranial electrical neuromodulation of the central nervous system is used as a non-invasive method to induce neural and behavioral responses, yet targeted non-invasive electrical stimulation of the brain with high spatial resolution remains elusive. This work demonstrates a focused, steerable, high-density epicranial current stimulation (HD-ECS) approach to evoke neural activity. Custom-designed high-density (HD) flexible surface electrode arrays are employed to apply high-resolution pulsed electric currents through skull to achieve localized stimulation of the intact mouse brain.

Residual voltage as an ad-hoc indicator of electrode damage in biphasic electrical stimulation.

We derive and demonstrate how residual voltage (RV) from a biphasic electrical stimulation pulse can be used to recognize degradation at the electrode-tissue interface.Using a first order model of the electrode-tissue interface and a rectangular biphasic stimulation current waveform, we derive the equations for RV as well as RV growth over several stimulation pulses. To demonstrate the use of RV for damage detection, we simulate accelerated damage on sputtered iridium oxide film (SIROF) electrodes using potential cycling.

Hydrogel-based electrodes for selective cervical vagus nerve stimulation.

Electrical vagus nerve stimulation (VNS) has the potential to treat a wide variety of diseases by modulating afferent and efferent communication to the heart, lungs, esophagus, stomach, and intestines. Although distal vagal nerve branches, close to end organs, could provide a selective therapeutic approach, these locations are often surgically inaccessible. In contrast, the cervical vagus nerve has been targeted for decades using surgically implantable helix electrodes to treat epileptic seizures and depression; however, to date, clinical implementation of VNS has relied on an electrode with contacts that fully wrap around the nerve, producing non-selective activation of the entire nerve.

Inkjet Printing of Curing Agent on Thin PDMS for Local Tailoring of Mechanical Properties.

Rapid prototyping of thin, stretchable substrates with engineered stiffness gradients at desired locations has potential impact in the robustness of skin-wearable electronics, as the gradients can inhibit cracking of interconnect and delamination of embedded electronic chips. Drop-on-demand inkjetting of thinned polydimethylsiloxane (PDMS) curing agent onto a spin-cast 80 µm-thick 20:1 (base: curing agent) PDMS substrate sets the elastic modulus of the subsequently cured film with sub-millimeter accuracy. The inkjet process creates digitally defined stiffness gradient spans as small as 100 µm for single droplets.

Parylene neural probe with embedded CMOS multiplexing amplifier.

We present a method for embedding integrated circuit chips in parylene neural probes where Anisotropic Conductive Film (ACF) electrically and physically connects the chip to the probe. Adequate insulation of the assembly is verified up to 150 h in vitro (testing ongoing). A custom-designed 8-to-1 multiplexing amplifier for neural application was fabricated in a 0.