Systems and methods for preventing contamination of recorded biological signals during surgery
View Patent ↗A system for recording, processing, and monitoring biosignals is provided, the system being configured to suspend data acquisition whenever an electric surgical tool or other generator of high frequency interference is in use. Such a system may protect the hardware of the system and reduce or eliminate the acquisition of distorted signals. The system of some embodiments includes an amplifier system configured to detect the presence of high frequency interference. Related methods are also disclosed.
1. An amplifier system, comprising:
an evoked potential detection device including at least one data processor and at least one memory storing instructions for stimulating a peripheral nerve and recording one or more detected signals, the evoked potential detection device further comprising:
a first signal pathway and a second signal pathway coupled with the evoked potential detection device, each signal pathway having an input for the detected signal, wherein the detected signal comprises a target signal and high frequency interference,
wherein the first signal pathway is configured to amplify the target signal and comprises, in order:
a low pass filter,
an amplifier,
an analog to digital converter, and
a microprocessor;
wherein the second signal pathway is configured to detect the high frequency interference and comprises:
a band pass filter or high pass filter electrically coupled to a radiofrequency detector,
a comparator,
a digital to analog converter, and
the microprocessor of the first signal pathway;
wherein the comparator is configured to compare a first amplitude of a first signal entering from a first leg and a second amplitude of a second signal entering from a second leg, the first leg of the comparator being electrically coupled to an output from the radiofrequency detector, and the second leg being electrically coupled via the digital to analog converter to an output from the microprocessor;
wherein the microprocessor is electrically coupled to an output from the comparator and is configured to detect the presence of high frequency interference within the detected signal when the first amplitude is greater than the second amplitude; and
wherein the evoked potential detection device is configured to temporarily suspend data acquisition upon detection of the high frequency interference.
2. The amplifier system of claim 1 , wherein the second signal is a threshold signal set by a user interacting with the microprocessor via a user interface.
3. The amplifier system of claim 1 , wherein the system is configured to temporarily suspend signal amplification upon detection of high frequency interference.
4. The amplifier system of claim 1 , further comprising a control line electrically connecting the microprocessor to the amplifier, wherein the control line is configured to deliver an interrupt signal to the amplifier upon detection of high frequency interference.
5. The amplifier system of claim 1 , further comprising one or more low pass filters positioned between the comparator and the microprocessor.
6. The amplifier system of claim 1 , wherein the band pass filter of the second signal pathway comprises one or more inductors, capacitors, or a combination thereof, configured to pass a frequency band of interest while eliminating signals outside the frequency band of interest.
7. The amplifier system of claim 6 , wherein the frequency band of interest is 200 kHz to 6 MHz.
8. The amplifier system of claim 1 , wherein the radiofrequency detector comprises an ultrafast diode, a capacitor connected to ground, and a parallel shunt resistor connected to ground.
9. The amplifier system of claim 1 , wherein the target signal is a biological signal.
10. The amplifier system of claim 9 , wherein the biological signal is an evoked potential.