A Tripolar Current-Steering Stimulator ASIC for Field Shaping in Deep Brain Stimulation

Abstract

A significant problem with clinical deep brain stimulation (DBS) is the high variability of its efficacy and the frequency of side effects, related to the spreading of current beyond the anatomical target area. This is the result of the lack of control that current DBS systems offer on the shaping of the electric potential distribution around the electrode. This paper presents a stimulator ASIC with a tripolar current-steering output stage, aiming at achieving more selectivity and field shaping than current DBS systems. The ASIC was fabricated in a 0.35-μ m CMOS technology occupying a core area of 0.71 mm(2). It consists of three current sourcing/sinking channels. It is capable of generating square and exponential-decay biphasic current pulses with five different time constants up to 28 ms and delivering up to 1.85 mA of cathodic current, in steps of 4 μA, from a 12 V power supply. Field shaping was validated by mapping the potential distribution when injecting current pulses through a multicontact DBS electrode in saline.

An Inductively Coupled Power and Data Link with Self-referenced ASK Demodulator and Wide-range LDO for Bio-implantable Devices

“…where 0 f is the resonance frequency, 1 Q is the quality factors for the primary, and 2 Q is the quality factor for the secondary resonator, respectively [6,10]. In practice, the load (R L ) is set by the power consumption of the internal circuit driven by the voltage regulator.…”

“…Deep brain stimulators have been successfully demonstrated as a clinical tool for the treatment of chronic pain and movement disorders such as Parkinson's disease [1][2][3]. These medical devices often employ the near-field inductive coupling for power and data delivery to implanted devices as a replacement for transcutaneous wires or implantable batteries that may cause infections in human body or require a periodic surgery.…”

Advances in Microelectronics for Implantable Medical Devices

“…For current sources with high output impedance, the stimulus current amplitude is not affected by changes in the load. Examples of integrated currentmode stimulators in CMOS technology for various applications such as nerve root stimulation for spinal cord injury, vestibular prosthesis for balance disorders, and deep brain stimulation for severe movement disorders are described in [11,[69][70][71][72][73]. The current amplitude range is from 1 mA to 16 mA.…”

“…DBS emerged from heart pacemaker technology and hence is also called a brain pacemaker. Current developments are focused on the design of cranialmounted inductively-powered DBS systems [10] to reduce the length of the leads from the stimulator to the electrodes and novel stimulation techniques using high-density segmented electrodes, which can enable current-steering and electric field shaping capability [11,12]. In addition, recent papers have reported the development of prototype closed-loop (i.e., sense and stimulate) neuroprosthetic devices for applications such as vestibular prosthesis [13] and epilepsy [14,15].…”

Low-power circuit structures for chip-scale stimulating implants

“…Reduction in implant volume, reduction in implant power dissipation per function, increase in stimulation site count, and advanced builtin analogue and digital signal processing, in particular, are examples of key advances in enabling electronics technologies. In recent years, a wealth of electronic circuits and systems for an increasingly diverse field of neuro-stimulators have thus been reported: for instance functional electrical stimulators [1], bladder control stimulators [2], spinal cord stimulators [3], deep brain stimulator [4], and of course cochlear implants [5] and pacemakers [6].…”