Abstract: Methods and devices for measuring blood flow velocity are provided. The device may include a wave source and at least two detectors positioned along a blood vessel. The wave source, which may include an ultrasound transducer or a mechanical source, is configured to induce a pressure wave in blood flowing in a blood vessel. In one example, the detectors are both positioned downstream of the wave source, with respect to the direction of blood flow. In another example, one detector is positioned upstream of the wave source, and a second detector is positioned downstream of the wave source. The difference in time it takes for the induced pressure wave to reach the first and the second detectors is indicative of the velocity of blood flow in the vessel.

Abstract: Optical measurement of physiological parameters with wearable devices often includes measuring signals in the presence of significant noise sources. These noise sources include, but are not limited to, noise associated with: variable optical coupling to skin or tissue, variations in tissue optical properties with time due to changes in humidity, temperature, hydration, variations in tissue optical properties between individuals, variable coupling of ambient light sources into detectors, and instrument and detector noise, including electrical noise, radio frequency or magnetic interference, or noise caused by mechanical movement of the detector or its components. The present disclosure includes devices and methods configured to produce representations of the raw data in which noise, broadly defined, is separated from the data of interest. The disclosed devices and methods may include subtracting or calibrating out these noise sources and other spurious fluctuations in wearable devices with optical sensors.

Abstract: An imaging agent for detecting analytes in an environment includes functionalized nanodiamonds and functionalized magnetic particles that can selectively interact with an analyte. Each functionalized nanodiamond contains at least one color center configured emit light in response to illumination. At least one property of the light emitted by the color centers is related to the proximity of the functionalized magnetic particles to the color centers. This property can be detected to determine that the functionalized nanodiamonds are proximate to the functionalized magnetic particles, to determine that the functionalized nanodiamonds and the functionalized magnetic particles are interacting with the analyte, or other applications. Devices and methods for detecting properties of the analyte by interacting with the functionalized nanodiamonds and functionalized magnetic particles are also provided.

Abstract: An engineered particle for detecting analytes in an environment includes an electromagnetic receiver that is configured to preferentially receive electromagnetic radiation of a specified polarization relative to the orientation of the electromagnetic receiver. The engineered particle additionally includes an energy emitter coupled to the electromagnetic receiver such that a portion of electromagnetic energy received by the electromagnetic receiver is transferred to and emitted by the energy emitter. The engineered particles are functionalized to selectively interact with an analyte. The engineered particle can additionally be configured to align with a directed energy field in the environment. The selective reception of electromagnetic radiation of a specified polarization and/or alignment with a directed energy field can enable orientation tracking of individual engineered particles, imaging in high-noise environments, or other applications.

Abstract: An imaging agent for detecting analytes in a biological environment includes functionalized, silicon vacancy center-containing nanodiamonds. Individual nanodiamonds of the imaging agent include at least one silicon vacancy center. The at least one silicon vacancy center can emit light having a wavelength in a narrow band in response to illumination having any wavelength in a wide range of wavelengths. The nanodiamonds are functionalized to selectively interact with an analyte of interest. The nanodiamonds can additionally include other color centers, and the imaging agent can include a plurality of sets of nanodiamonds having detectably unique ratios of silicon vacancy centers to other color centers. The silicon vacancy centers in the nanodiamonds can have a preferred orientation enabling orientation tracking of individual nanodiamonds or other applications. A method for detecting properties of the analyte of interest by interacting with the imaging agent is also provided.

Abstract: A system for modulating a response signal includes functionalized particles configured to interact with target analytes, a detector configured to detect an analyte response signal transmitted from the body, a modulation source configured to modulate the analyte response signal, and a processor configured to non-invasively detect the one or more target analytes by differentiating the analyte response signal from a background signal, at least in part, based on the modulation. The analyte response signal is related to the interaction of the target analytes with the functionalized particles. In some examples, the system may also include magnetic particles and a magnetic field source sufficient to distribute the magnetic particles into a spatial arrangement in the body. The analyte response signal may be differentiated from the background signal, at least in part, based on modulation of the signals due, at least in part, to the spatial arrangement of the magnetic particles.

Abstract: A method for modulating a response signal includes introducing functionalized magnetic particles configured to interact with target analytes into the body, applying a magnetic field sufficient to draw the functionalized magnetic particles towards a surface of the lumen of subsurface vasculature closest to an internally or externally applied mask having a spatial arrangement, and detecting a response signal, which includes a background signal and an analyte response signal, transmitted from the subsurface vasculature. The analyte response signal related to interaction of the functionalized magnetic particles with the target analytes and is modulated with respect to the background signal due, at least in part, to the spatial arrangement of the mask. The target analytes may be non-invasively detected by differentiating the analyte response signal from the background signal due, at least in part, to the modulation of the analyte response signal.

Abstract: A method for modulating a response signal includes introducing functionalized particles into a lumen of subsurface vasculature, wherein the functionalized particles are configured to interact with one or more target analytes present in blood circulating in the subsurface vasculature; and non-invasively detecting the one or more target analytes. A response signal, which may include a background signal and an analyte response signal related to interaction of the functionalized particles with the one or more target analytes, is transmitted from the subsurface vasculature. A modulation configured to alter the response signal such that the analyte response signal is affected differently than the background signal may be applied to a portion of subsurface vasculature. Analyte detection may be achieved by differentiating the analyte response signal from the background signal.