Implantable telemetry for small animals

A series of totally implantable telemetry devices for use in measuring deep body parameters in small animals were developed. Under a collaborative agreement with NASA, several of these systems; the continuous wave Doppler ultrasonic flowmeter, the multichannel telemetry system, and the inductively-powered dual channel cardiac pacer were evaluated in a series of ten mongrel dogs (15 to 20 kg.). These systems were used to measure ascending aortic and coronary blood flow, aortic pressure, and subcutaneous EKG

Micropower circuits for bidirectional wireless telemetry in neural recording applications

Journal ArticleState-of-the art neural recording systems require electronics allowing for transcutaneous, bidirectional data transfer. As these circuits will be implanted near the brain, they must be small and low power. We have developed micropower integrated circuits for recovering clock and data signals over a transcutaneous power link. The data recovery circuit produces a digital data signal from an ac power waveform that has been amplitude modulated. We have also developed an FM transmitter with the lowest power dissipation reported for biosignal telemetry. The FM transmitter consists of a low-noise biopotential amplifier and a voltage controlled oscillator used to transmit amplified neural signals at a frequency near 433 MHz. All circuits were fabricated in a standard 0.5- m CMOS VLSI process. The resulting chip is powered through a wireless inductive link. The power consumption of the clock and data recovery circuits is measured to be 129 W; the power consumption of the transmitter is measured to be 465 W when using an external surface mount inductor. Using a parasitic antenna less than 2 mm long, a received power level was measured to be 59 73 dBmat a distance of one meter

Ultrasonic Doppler measurement of renal artery blood flow

An extensive evaluation of the practical and theoretical limitations encountered in the use of totally implantable CW Doppler flowmeters is provided. Theoretical analyses, computer models, in-vitro and in-vivo calibration studies describe the sources and magnitudes of potential errors in the measurement of blood flow through the renal artery, as well as larger vessels in the circulatory system. The evaluation of new flowmeter/transducer systems and their use in physiological investigations is reported

Characteristics of Telemetry Interference with Pacemakers Caused by Digital Media Players

Background: Contemporary implantable heart rhythm devices communicate multiple complex data simultaneously using radiofrequency telemetry. Interference in communication can expose them to the risk of potential corruption, leading to adverse clinical consequences. Methods & Results: We studied the characteristics of interference with uplink (real time intracardiac electrograms, marker channel, and stored histograms) and downlink (attempt to program a change in the lower rate limit, the pacing mode, and the ventricular lead configuration) data transmission between the wand and the pacemaker caused by digital media players (iPods—Photo and 3G) in 50 patients. We also measured and characterized worst-case magnetic field emissions (MFE) from the wand (≤0.4 μT), pacemaker (≤0.004 μT), and iPod (≤0.05 μT) during telemetry to understand the modulation techniques and safety protocols employed during data transmission. Telemetry interference (TI) manifested as high-frequency spikes (24.4%), blanking (17.7%) and interruption (22.2%), or delay (17.6%) in transmission with warning on programmer's screen. TI occurred in 25.6% of patients when the iPod was “on” and in 13% even with the iPod turned “off.” There were no inaccuracies in downlinked data when the downlink communication was successful. Wanded telemetry utilizes low-frequency (30–300 kHz) radiowaves and simple digital modulation techniques at relatively slow rates for “sequential” data transmission protected by a continuous “handshake.” Emissions from iPods in that range interrupt the telemetry link but are too weak to cause pacemaker malfunction through corruption of vital data. Conclusion: Low-power MFE from iPods can produce interference with establishment and maintenance of a telemetry link and can cause TI with transmission of real time data, but because of continuous check protocols, do not corrupt the stored and vital downlink data. (PACE 2010; 33:712–720)Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78697/1/j.1540-8159.2009.02672.x.pd

A wireless implantable multichannel digital neural recording system for a micromachined sieve electrode

This paper reports the development of an implantable, fully integrated, multichannel peripheral neural recording system, which is powered and controlled using an RF telemetry link, The system allows recording of +/-500 mu V neural signals from axons regenerated through a micromachined silicon sieve electrode, These signals are amplified using on-chip 100 Hz to 3.1 kHz bandlimited amplifiers, multiplexed, and digitized with a low-power (<2 mW), moderate speed (8 mu s/b) current-mode 8-b analog-to-digital converter (ADC), The digitized signal is transmitted to the outside world using a passive RF telemetry link, The circuit is implemented using a bipolar CMOS process, The signal processing CMOS circuitry dissipates only 10 mW of power from a 5-V supply while operating at 2 MHz and consumes 4 x 4 mm(2) of area, The overall circuit including the RF interface circuitry contains over 5000 transistors, dissipates 90 mW of power, and consumes 4 x 6 mm(2) of area

A new optical UWB modulation technique for 250Mbps wireless link in implantable biotelemetry systems

We propose a new UWB modulation technique for wireless optical communications in transcutaneous biotelemetry. The solution, based on the generation of sub-nanoseconds laser pulses, allows for a high data rate link whilst achieving a significant power reduction (energy per bit) compared to the state-ofthe- art. These features make this particularly suitable for emerging biomedical applications such as implantable neural/biosensor systems. The relatively simple architecture consists of a transmitter and receiver that can be integrated in a standard CMOS technology in a compact Silicon footprint (lower than 1mm^2 in a 0.18μm technology). These parts, optimised for low-voltage/low-power operation, include coding and decoding digital systems, biasing and driving analogue circuits for laser pulse generation and photodiode signal conditioning. Experimental findings with prototype PCBs have validated the new paradigm showing the system capabilities to achieve a BER less than 10^-9 with data rate up to 250Mbps and estimated total power consumption lower than 5mW

A High TCMRR, Inherently Charge Balanced Bidirectional Front-End for Multichannel Closed-Loop Neuromodulation

This paper describes a multichannel bidirectional front-end for implantable closed-loop neuromodulation. Stimulation artefacts are reduced by way of a 4-channel H-bridge current source sharing stimulator front-end that minimizes residual charge drops in the electrodes via topology-inherent charge balancing. A 4-channel chopper front-end is capable of multichannel recording in the presence of artefacts as a result of its high total common-mode rejection ratio (TCMRR) that accounts for CMRR degradation due to electrode mismatch. Experimental verification of a prototype fabricated in a standard 180 nm process shows a stimulator front-end with 0.059% charge balance and 0.275 nA DC current error. The recording front-end consumes 3.24 µW, tolerates common-mode interference up to 1 Vpp and shows a TCMRR > 66 dB for 500 mVpp inputs.Ministerio de Economía y Competitividad TEC2016-80923-POffice of Naval Research (USA) N00014111031