Wireless data telemetry for implantable medical devices (IMDs) has, in general, been limited to a few Mbps, and used for applications such as transmitting recordings from an implanted monitoring device, or uploading commands to an implanted stimulator. However, modern neural interfaces need to record high resolution potentials from hundreds of neurons; this requires much higher data rates. While fast wireless communication is possible using existing standards such as WiFi, power consumption demands are far too high for IMDs. Short range inductive link based telemetry, in particular impulse-based systems such as pulse-harmonic modulation (PHM), have demonstrated transfer speeds of up to 20 Mbps with a small power budget. However, these systems require complex and precise circuits, making them potentially susceptible to inter-symbol-interference. This work presents a new method named Short-range Quality-factor Modulation (SQuirM), which retains the low power consumption and high data rate of PHM, while improving the resilience of the system and simplifying the circuit design. Transmitter and receiver circuits were fabricated using 0.35 μm CMOS. The circuits were capable of reliably transceiving data at speeds of up to 50.4 Mbps, with a BER of < 4.5 × 10^-10 , and a transmitter energy consumption of 8.11 pJ/b.

@en

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

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

This paper presents the operation of a dualmode wideband CMOS analog front-end (AFE) for electrical impedance spectroscopy. The chip combines two current-readout (CR) channels and four voltage-readout (VR) channels suitable for both bipolar and tetrapolar EIS analysis. The chip addresses the need for flexible readout units for real-time simultaneous single-cell and large scale tissue/organ analysis. Postlayout simulations show that the VR channel is capable of wideband operation up to 12 MHz with noise floor as low as 16.4 nV/Hz^1/2. A 2-bit control allows to select between a high-frequency low-gain channel and a bandwidth-limited high-gain channel. Each VR channel occupies an area of 0.48 mm². The CR channel is capable of 80 dB of dynamic range, by converting currents between 1 nA to 10μA, while achieving a noise floor of 1.4 pA/Hz^1/2. An automatic gain control (AGC) unit can be enabled in order maintain the sensor signal within the ADC dynamic range. Each CR channel occupies an area of 0.21 mm². The chip consumes between 290 μA and 690 μA per channel and operates from a 1.8 V supply. The chip will be part of a fully flexible and configurable dual-mode EIS systems for impedance sensors and bioimpedance analysis.

@en

This paper presents a second-generation integrated circuit for the Active Books neural stimulation microsystem. It provides multi-channel stimulation with versatile control of stimulation profiles and reduced crosstalk from other stimulation channels. The new design features enhanced safety by monitoring the temperature and humidity inside the micropackage, and the peak electrode voltage at any stimulating electrode. The humidity sensor uses an interdigitated capacitor covered by a passivation layer and a polyimide covering. To boost sensitivity in the operating range of interest, the temperature sensor uses a temperature-insensitive current that is subtracted from a proportional-to-absolute-temperature current. A 3-b analog-to-digital converter is used to record the peak electrode voltage. All sensor data is sent to an implanted central hub using bidirectional connection with error checking. Both the stimulation electronics and sensors are integrated on a 6.2 mm 4 mm silicon die using XFAB's 0.6- μ m CMOS high-voltage process. No post-processing steps are involved. The stimulator uses a five-wire cable to provide the power supply and bidirectional data signals. The chip operates from a 7.5-18 V power supply and can generate stimulation currents of 1 mA, 4 mA or 8 mA with a pulse duration of 2 μ S-1.07 ms. The humidity sensor output varies linearly with relative humidity (RH) with a normalized sensitivity of 0.04%/%RH over the range of 20-90%RH. The temperature sensor has a nonlinearity of 0.4% over the range of 20-90 °C and a resolution of 0.12 °C. The stimulator is the first of its kind to include integrated temperature and humidity sensors.@en

This paper presents the preliminary design and simulation of a flexible and programmable analog front-end (AFE) circuit with current and voltage readout capabilities for electric impedance spectroscopy (EIS). The AFE is part of a fully integrated multifrequency EIS platform. The current readout comprises of a transimpedance stage and an automatic gain control (AGC) unit designed to accommodate impedance changes larger than 3 order of magnitude. The AGC is based on a dynamic peak detector that tracks changes in the input current over time and regulates the gain of a programmable gain amplifier in order to optimise the signal-to-noise ratio. The system works up to 1 MHz. The voltage readout consists of a 2 stages of fully differential current-feedback instrumentation amplifier which provide 100 dB of CMRR and a programmable gain up to 20 V/V per stage with a bandwidth in excess of 10MHz.

@en