Pain control on demand based on pulsed radio-frequency stimulation of the dorsal root ganglion using a batteryless implantable CMOS SoC

Although pain is interpreted as the fifth vital sign by many professions, the presence of different degrees of pain significantly affects quality of life for many patients, especially the elderly [1]. Electrical stimulation to the central or peripheral neural conduction paths has been utilized in clinics to achieve effective pain relief [2]. The conventional scheme for pulsed radio-frequency (PRF) pain therapy uses thermal coagulation to permanently damage nerves by heat. This destructive method can cause severe side-effects such as hyper-sensitivity to pain after nerves regenerate. Thus, repeated surgery is needed. Additionally, the conventional design of an implantable system requires a battery for operation, often accounting for over 2/3 of the entire device volume. Therefore, a non-destructive and batteryless method using PRF for pain control is key for implantable systems. This work uses a batteryless implantable pain-control SoC that is effective in pain reduction, using a low stimulation voltage that avoids causing thermal damage to dorsal root ganglion (DRG) tissue. An animal study of neuropathic pain was previously designed with PRF parameters to control tissue temperature at ≪40°C via an external function generator [3]. This work now presents the implementation of this functionality on a CMOS SoC. Its effectiveness is demonstrated by observing the behavior of rats receiving localized bipolar stimulus to the DRG of the lumbar nerve.