An apparatus for measuring photoplethysmogram includes a ring structure with at least one photon source and at least one photon detector positioned on an inner surface of the ring structure. The apparatus further includes a controller configured to measure a preliminary photoplethysmogram during a first time period by taking a first number of samples, determine a form factor from the preliminary photoplethysmogram, determine an inter beat interval from the preliminary photoplethysmogram, and use the form factor and the inter beat interval to determine a second number of samples to be taken during a second time period of measurement of the photoplethysmogram and the distribution of the samples to be taken in function of time.

Various embodiments are described herein for a system and a method for assessing a risk of ventricular arrhythmias for a patient. For example, the method may comprise receiving ECG data obtained from the patient; analyzing the ECG data to detect abnormal QRS peaks; determining the risk of ventricular arrhythmias for the patient based on the detected abnormal QRS peaks; and providing an indication of the risk of ventricular arrhythmias for the patient. The system may be configured to perform this method.

Apparatus and methods remove a voltage offset from an electrical signal, specifically a biomedical signal. A signal is received at a first operational amplifier and is amplified by a gain. An amplitude of the signal is monitored, by a first pair of diode stages coupled to an output of the first operational amplifier, for the voltage offset. The amplitude of the signal is then attenuated by the first pair of diode stages and a plurality of timing banks. The attenuating includes limiting charging, by the first pair of diode stages, of the plurality of timing banks and setting a time constant based on the charging. The attenuating removes the voltage offset persisting at a threshold for a duration of at least the time constant. Saturation of the signal is limited to a saturation recovery time while the saturated signal is gradually pulled into monitoring range over the saturation recovery time.

The provided systems, methods and devices describe lightweight, wireless tissue monitoring devices that are capable of establishing conformal contact due to the flexibility or bendability of the device. The described systems and devices are useful, for example, for skin-mounted intraoperative monitoring of nerve-muscle activity. The present systems and methods are versatile and may be used for a variety of tissues (e.g. skin, organs, muscles, nerves, etc.) to measure a variety of different parameters (e.g. electric signals, electric potentials, electromyography, movement, vibration, acoustic signals, response to various stimuli, etc.).

Systems and methods for electromagnetic field generator alignment are disclosed. In one aspect, the system includes an electromagnetic (EM) sensor configured to generate, when positioned in a working volume of the EM field, one or more EM sensor signals based on detection of the EM field, the EM sensor configured for placement on a patient. The system may also include a processor and a memory storing computer-executable instructions to cause the processor to: determine a position of the EM sensor with respect to the field generator based on the one or more EM sensor signals, encode a representation of the position of the EM sensor with respect to the working volume of the EM field, and provide the encoded representation of the position to a display configured to render encoded data.

Various embodiments of an interface control subsystem may be used between an electrode terminal and a recording terminal of a neurostimulation and neurorecording system. The interface control subsystem may operate in three modes. In a disable mode, a first transistor and a second transistor disposed between the electrode terminal and the recording terminal may operate in a cutoff region and generate a high impedance. In an active mode, the first transistor and the second transistor may operate in a saturation region and generate a low impedance. In a stimulation mode, the first transistor and the second transistor operate in a triode region and generate an impedance between the high impedance of the disable mode and the low impedance of the active mode. The interface control subsystem may further limit voltage at the recording terminal in response to a detected overvoltage condition.

Systems, devices, and techniques are described for analyzing evoked compound action potentials (ECAP) signals to assess the effect of a delivered electrical stimulation signal. In one example, a system includes processing circuitry configured to receive ECAP information representative of an ECAP signal sensed by sensing circuitry, and determine, based on the ECAP information, that the ECAP signal includes at least one of an N2 peak, P3 peak, or N3 peak. The processing circuitry may then control delivery of electrical stimulation based on at least one of the N2 peak, P3 peak, or N3 peak.

Methods, systems, and media are disclosed for detrending a bioelectric signal. In some embodiments, the disclosed system can include a processor configured to receive the bioelectric signal, identify at least one breakpoint section corresponds to a rapid change of amplitude of the bioelectric signal, smooth an amplitude of the bioelectric signal after the at least one breakpoint section; and reconstruct the bioelectric signal based on the smoothed amplitude of the bioelectric signal and a reset of the breakpoint section to remove extrinsic components caused by a non-biological factor from the bioelectric signal.

In one embodiment, a method includes receiving first cardiac signals captured by at least one first sensing electrode in contact with tissue of a first living subject, injecting the received first cardiac signals into a length of wire, which outputs respective noise-added cardiac signals responsively to noise acquired in the wire, training an artificial neural network to remove noise from cardiac signals responsively to the received first cardiac signals and the respective noise-added cardiac signals, receiving second cardiac signals captured by at least one second sensing electrode in contact with tissue of a second living subject, and applying the trained artificial neural network to the second cardiac signals to yield noise-reduced cardiac signals.

There is provided a system and method for classifying time series data for state identification. The method including: training a machine learning model to classify occurrences of the state; receiving a new time series data stream; determining whether a current sample in the new time series data stream is an occurrence of the state by determining a classified feature vector, the classified feature vector determined by passing the current sample and samples in at least one continuous sampling window into the trained machine learning model, each continuous sampling window including a plurality of preceding samples from the time series data, an epoch for each respective continuous sampling window determined according to a respective exponential decay rate; and outputting the determination of whether the current sample is an occurrence of the state.