Battery-Free Dual-Channel Wireless Neurostimulator Using Passive Circuitry for Neuropathic Pain Modulation

Neuropathic pain caused by nervous system diseases or injuries is a complex condition with diverse pathological mechanisms and poses a significant burden to individuals and society. Typically, when pharmacological treatments are ineffective, neuromodulation techniques, such as spinal cord stimulation, deep brain stimulation, and motor cortex stimulation, are employed. Although these methods offer promising alternatives to pharmacological treatments, they require bulky implanted stimulators with batteries and complex circuitry. In this study, a miniaturized wireless dual-channel stimulator is developed that uses only passive circuit components. This wireless electroceutical approach enables multichannel stimulation using a single receiver coil with a tapping inductor. The miniaturized passive stimulator (9 × 13 × 3.4 mm³, 0.451 g) generates stimulus pulses for each channel. After implantation into a spared nerve injury rat model to stimulate the primary motor cortex, behavioral assessments using the Von Frey filament up-and-down method demonstrated significant pain alleviation following independent channel stimulation. The innovative approach advances the miniaturization of multichannel passive neurostimulators, thereby enhancing patient comfort and reducing surgical complications.