One-Time-Implantable Spinal Cord Stimulation System Prototype

Abstract

A prototype of a one-time-implantable spinal cord stimulation (SCS) system using wireless power and data-transmission techniques is presented in this paper. The power of the implant is induced by wireless coil coupling, and duplex amplitude-shift keying-load-shift keying wireless communication is used so that digital packets can be transmitted by the same inductive link. The proposed novel ASK demodulator attains high demodulation performance and small area without using any resistors and capacitors. The proposed SCS system utilizes many power saving schemes to reduce power dissipation (e.g., dual supply voltages on-chip, high-voltage impulse generation using small current, etc.). Meanwhile, the excess energy induced by the coils is stored in a rechargeable battery to extend the implant's operation time so that the number of battery replacement surgeries will be reduced significantly. The system-on-chip (SOC) is physically implemented on silicon and integrated in the implant as the system controller. The fabricated SOC area is 1410 × 1710 μm(2). Compared with existing commercial products, the proposed SCS system attains better flexibility and longer operation time.

A Discrete Controlled Fully Integrated Class E Coil Driver With Power Efficient ASK Modulation for Powering Biomedical Implants

“…The measured coil inductance was increased from 29. 8 to 38.6 . The volume of the ferrite object was .…”

“…This is denoted as . Based on (7), in (4) can also be expressed as (8) In addition, the condition in (6) can be rewritten as (9) For a given , can therefore be determined using (9). The peak values of and given as and can be derived using (2) and (3) as (10) (11) According to (7)-(10), the amplitude of the coil current can be controlled by adjusting the coil supply voltage directly without affecting .…”

“…To analyze MI at steady state with being turned on, the equations described in Section II-A can be used except that , , and are required to change to , , , and , respectively where . The values for and can be determined using (4) and (8). By substituting into (6) with the use of (7), , which is equal to , can be found as (30) Since has to be higher than , the maximum value for , , is limited to be .…”

“…Although different methods for harvesting energy from different energy sources, including the optical source [1] and the ultrasonic energy source [2], have been considered recently by different researchers, the transcutaneous power transmission based on inductive coupling [3]- [13] is still the most common way utilized for delivering power wirelessly across the human skin to power the biomedical implants. Although some biomedical implants are designed to obtain power directly from the batteries within the implants, these batteries are still required to be recharged wirelessly [8], [14]- [17]. In an inductive coupling transcutaneous power transmission system, a primary coil, , located in the controller outside the body is used to inductively couple and power a secondary coil, , located in the implant as shown in Fig.…”

Batteries Not Included: A Mat-Based Wireless Power Transfer System for Implantable Medical Devices As a Moving Target

“…The batteries of these implantable devices can be recharged by external wireless chargers. Unfortunately, the chargers are often inconvenient for patients since losing power by the implant is often risky [20]. Therefore, a new technology transmitting both signal and energy, requiring no attachments to the body of humans or animals, and allowing full freedom of motion within a space of sufficient size represents a significant advance in the field of medical implants.…”