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Grass Technologies amplifiers are world-renowned in the field of neurophysiology for their quality, reliability, simplicity, and serviceability.

The amplifier system provides for patient safety isolation, signal conditioning (physiological signal amplification and filtering), and digitization. Communications with a host computer are accomplished using TCP/IP protocol over an Ethernet network or dedicated cable. A host computer, using TWin software, sets the sample rate, starts and stops the data transmission, monitors the digital data, and stores it to hard disk or an optional file server.

AURA (Ambulatory Universal Recording Amplifier) amplifier system has a front-end sampling rate of 400 Hz (record 200 or 400 Hz, user definable). The electrode input jack box provides 32 AC inputs, 2 reference inputs and 2 ground inputs. The redundant references and grounds provide reliability and signal integrity during long-term monitoring procedures.

The 32-channel system has the capability of recording data directly to a PC or can be untethered for temporary ambulatory recordings. The compact and lightweight design of AURA offers maximum patient comfort, without sacrificing the ruggedness required for long-term studies.

AURA is typically tethered to the base station, which streams data to a host computer running TWin. However, AURA is also capable of operating untethered. When untethered, AURA will run off of an internal battery and save data to a CompactFlash® (CF) memory card. AURA is capable of over 2 hours of untethered recording. If there is an immediate need to download and review the data stored on the CompactFlash memory card, the CF can be removed from AURA and the data can be downloaded quickly via a USB CompactFlash Reader.

With AURA, the patient can travel from their patient room to a day room. When the patient arrives at the day room, AURA simply needs to be plugged into any base station located in that room. Our TWin recording software will recognize that the patient has switched to a new base station, and tethered recording will resume again.

An optional external battery pack is available to enable recording of 24-hour ambulatory EEG studies.

An 8-channel DC input module and optional pulse oximeter (SpO2/HR) allow for an additional 10 channels of data. This flexibility allows for wide range of physiological parameters to be monitored and recorded.

An intuitive user interface with LCD screen is present with the base station. From the base station itself, the technologist is able to implement such features as electrode impedance checking, amplifier calibration, and photic stimulator control. Also from the LCD display it is possible to obtain information such as connection status to the host computer, and oximetry/pulse rate information if an oximeter is in use.

The AURA-LTM64 amplifier, with integrated electrode input connections, is designed for use either as a bedside amplifier or as a wearable cabled-telemetry amplifier unit which allows the patient to have greater freedom of movement within their patient room. Provided accessories include a patient-worn pouch and 33-foot (10 m) patient cable. The integrated electrode input connections provides 64 AC inputs, 2 reference electrode inputs, and 2 ground inputs. Two amplifiers are connected for 128-channel recordings using a single link cable between them. Jack box adhesive labels are provided for labeling the inputs with international 10-20 and 1-64 numerical nomenclature, 10-10 nomenclature, and/or 65-128 nomenclature. The AURA-LTM64 64/128 amplifiers are modular and can be used with multiple recording systems.

When used for scalp recording, the amplifiers built-in electrode impedance meter can be activated via software from the recording PC, or by pressing the impedance button on the amplifier. The electrode connector inputs exceeding the user-defined impedance value will light up, making it easy for the technologists to identify which electrodes need attention. When used for invasive electrode recordings, the built-in impedance meter is disabled.

AURA-LTM64 amplifier system’s maximum possible sample rate is 3200 samples per second (64 channels) with a maximum possible bandwidth up to 1000 Hz *. Auxiliary inputs are also available for connecting a Patient Event Push Button and an optional photic stimulator.

* Frequency response is approximately 1/3 of the front end sampling rate. The sampling rate and the storage rate is set by TWin software and available sampling rates are dependent on the TWin software version.