A 97-Channel Read-Out ASIC for an Electrophysiological Mapping Catheter With an Optical Link.

Electrophysiological (EP) mapping catheters are medical equipment, which are widely used to diagnose and treat atrial fibrillation. The electrophysiology signals are sensed by the catheter's electrodes, for which a large electrode count becomes more and more essential because of the demand for a higher local resolution. A drawback of the large electrode count is the effort to pass through and to integrate the wires inside the catheter shaft. To overcome with this issue, this article describes the realization of an EP ASIC, which is placed close to the 97 electrodes and to perform an in-tip digitization. Thanks to an integrated optical link, only a single fiber is required to connect the catheter tip to an externally located electro-optical unit and thus shrinking the shaft volume to a minimum. The fiber is used to guide light from the electro-optical unit to the catheter tip and illuminate a blue LED, which is located close to the EP ASIC and acts as a photovoltaic cell. The EP ASIC is designed to use the LED as power source and a data transceiver while performing signal conditioning and digitization of the EP signals at the same time. The EP signals are captured with the ASIC's multi-channel read-out circuit consisting of 97 fully differential preamplifiers and additional filter stages. A switch network sequentially selects one single channel for further amplification and digitization of the EP signal. The read-out circuit is designed to process signals in the range of 500 µVpp to 20 mVpp with a bandwidth of 5 Hz to 100 Hz.

A 96-Channel Electrophysiology Catheter with Integrated Read-Out ASIC and Optical Link.

This paper describes a realization of an electrophysiology (EP) catheter with 96 electrodes which requires no electrical wiring to the outside by relying on an optical link for both power supply and data communication. The catheter tip is constructed from a liquid crystal polymer (LCP) material. It features 96 gold electrodes, which are uniformly arranged along an expandable basket. An integrated ASIC amplifies, filters and digitizes the EP signals and establishes communication to a data processing unit outside the patient's body. The optical interface consists of a conventional multi-mode fiber and a single blue LED inside the catheter. The external unit used to generate optical power, establish communication and perform data post-processing comprises a laser module, optics, and electrical components. The catheter is designed to capture EP signals in the range of 600 µVpp to 20 mVpp in a frequency range between 8 Hz and 120 Hz.