A Versatile Hermetically Sealed Microelectronic Implant for Peripheral Nerve Stimulation Applications

Abstract

This article presents a versatile neurostimulation platform featuring a fully implantable multi-channel neural stimulator for chronic experimental studies with freely moving large animal models involving peripheral nerves. The implant is hermetically sealed in a ceramic enclosure and encapsulated in medical grade silicone rubber, and then underwent active tests at accelerated aging conditions at 100°C for 15 consecutive days. The stimulator microelectronics are implemented in a 0.6-μm CMOS technology, with a crosstalk reduction scheme to minimize cross-channel interference, and high-speed power and data telemetry for battery-less operation. A wearable transmitter equipped with a Bluetooth Low Energy radio link, and a custom graphical user interface provide real-time, remotely controlled stimulation. Three parallel stimulators provide independent stimulation on three channels, where each stimulator supports six stimulating sites and two return sites through multiplexing, hence the implant can facilitate stimulation at up to 36 different electrode pairs. The design of the electronics, method of hermetic packaging and electrical performance as well as in vitro testing with electrodes in saline are presented.

Wireless Battery-free and Fully Implantable Organ Interfaces

“…On the left is a hermetically sealed microelectronic implant for peripheral nerve stimulation. 203 This fully implantable device consists of a ceramic casing encapsulated in medical-grade silicone rubber. This encapsulation approach is robust and offers excellent longevity, although it lacks conformality and flexibility, and is not suitable for thin, compliant electronics.…”

“…Copyright 2021 The Author(s), under exclusive license to Springer Nature America, Inc. d) Common encapsulation methods for chronic use devices. From left to right: Hermetically sealed microelectronic implant for peripheral nerve stimulation . Reproduced with permission.…”

“…Figure d contains four approaches to long-term device encapsulation, where encapsulants must serve as a barrier against gas and liquid transmission to enable device lifetimes spanning months to decades. On the left is a hermetically sealed microelectronic implant for peripheral nerve stimulation . This fully implantable device consists of a ceramic casing encapsulated in medical-grade silicone rubber.…”

A Fully Implantable Opto-Electro Closed-Loop Neural Interface for Motor Neuron Disease Studies

“…In the event of device failure, deionized water will accelerate the failure rate. Using deionized water is a harsher test condition for evaluating the safety of the device for implantation [36]. During the test, the implant was wirelessly powered by the transmitter.…”

Initial Life Test of Silicone Encapsulated FR 4 Printed Circuit Boards for Pre-Clinical Active Implants

“…Good silicone adhesion has been achieved to alumina ceramic substrates. To accelerate active implant innovation, it would be valuable to use prototype PCBs in pre-clinical studies including traditional glass-fibre-reinforced epoxy laminate (FR4) materials [7]. Promising lifetimes for silicone encapsulated FR4 PCB implants have been demonstrated [7,8].…”