A fully implantable multi-channel neural prosthesis for epidural stimulation will be demonstrated. The prosthesis features three telemetry-operated independent stimulators providing in total eighteen stimulation channels. The stimulator circuits were implemented in a 0.6-μm CMOS technology. The prosthesis is protected in a hermetically sealed ceramic enclosure and encapsulated in medical grade silicone rubber for long-term implantation. During the live demonstration in-vitro tests with electrodes in saline will be performed with the prosthesis operated wirelessly from a remote computer.@en

A fully-integrated complementary metal-oxide semiconductor (CMOS) sensor for combined temperature and humidity measurements is presented. The main purpose of the device is to monitor the hermeticity of micro-packages for implanted integrated circuits and to ensure their safe operation by monitoring the operating temperature and humidity on-chip. The smart sensor has two modes of operation, in which either the temperature or humidity is converted into a digital code representing a frequency ratio between two oscillators. This ratio is determined by the ratios of the timing capacitances and bias currents in both oscillators. The reference oscillator is biased by a current whose temperature dependency is complementary to the proportional to absolute temperature (PTAT) current. For the temperature measurement, this results in an exceptional normalized sensitivity of about 0.77%/°C at the accepted expense of reduced linearity. The humidity sensor is a capacitor, whose value varies linearly with relative humidity (RH) with a normalized sensitivity of 0.055%/% RH. For comparison, two versions of the humidity sensor with an area of either 0.2 mm2or 1.2 mm2 were fabricated in a commercial 0.18 μm CMOS process. The on-chip readout electronics operate from a 5 V power supply and consume a current of approximately 85 μA.@en

Powering of medical implants by inductive coupling is an effective technique, which avoids the use of bulky implanted batteries or transcutaneous wires. On the external unit side, class-D and class-E power amplifiers (PAs) are conventionally used, thanks to their high efficiency at high frequencies. The initial specifications driving this study require the use of multiple independent stimulators, which imposes serious constraints on the area and functionality of the external unit. An integrated circuit class-D PA has been designed to provide both small area and enhanced functionality, the latter achieved by the addition of an on-chip (PLL) a dead-time generator and a phase detector. The PA was designed in a 0.18-μm CMOS high-voltage process technology and occupies an area of 9.86 mm2. It works at frequencies up to 14 MHz and 30-V supply and efficiencies higher than 80% are obtained at 14 MHz. The PA is intended for a closed-loop transmitter system that optimizes power delivery to medical implants.@en

This paper presents a fully implantable multi-channel neural prosthesis for epidural stimulation. The prosthesis features three telemetry-operated independent stimulators providing in total eighteen stimulation channels. The stimulator circuits were implemented in a 0.6-μm CMOS technology. The prosthesis is protected in a hermetically sealed ceramic enclosure and encapsulated in medical grade silicone rubber. In-vitro measured results with electrodes in saline are presented.@en

The efficiency of an inductive power transfer link is greatly affected by misalignment between the coils, caused by the patient's movement, after implantation. In this paper we present the preliminary design of a coupling-insensitive system with an integrated class-D transmitter, suitable for powering epidural stimulation implants. The operation of the system is based on closed-loop modulation of the power delivered to the implant, to compensate for losses of coupling between coils after implantation. An integrated transmitter with efficiencies above 90% was designed to operate between 1 MHz and 14 MHz. The circuit design employs 0.18-um high-voltage CMOS technology. Simulations are presented to verify the operation of the circuit.@en

This paper presents a modified 1-Wire® based communication architecture between one active and several passive units of a distributed implantable system. The passive slave units are embedded in the electrode array. We focus in particular on the introduction of the physical and data link layer of the communication block, and present post-layout results of simulated data transfer between the hub and one slave in 0.18-μm power management CMOS technology. The communication block has a power consumption of 12.5 μW for a gross bit rate of 11.1 kBit/s. The proposed interface is inherently safe and suitable for exchanging status and sensor data between implants. The possibility to achieve higher symbol rates is discussed.@en

This paper discusses the design of an application-specific integrated circuit (ASIC) suitable for mounting on a multi-electrode array for epidural spinal cord stimulation in rats. The ASIC acts as a demultiplexer, driving 12 electrodes on the array in any configuration. It is capable of routing biphasic constant current pulses of up to 1 mA to high impedance loads (with a maximum output voltage swing of approximately 25 V) and is small enough to be implanted into a rat's spinal column. Communication with its driver is achieved via 3 wires to minimize the number of interconnections. The circuit was implemented in a 0.18-μm high-voltage CMOS technology occupying a core area of 0.36 mm 2. Power dissipation is about 110 μW. Post-layout simulations are presented which show the correct operation of the system.@en