This disclosure concerns methods and apparatus for interferometric spectroscopic measurements of particles with higher signal to noise ratio utilizing an infrared light beam that is split into two beams. At least one beam may be directed through a measurement volume containing a sample including a medium. The two beams may then be recombined and measured by a detector. The phase differential between the two beams may be selected to provide destructive interference when no particle is present in the measurement volume. A sample including medium with a particle is introduced to the measurement volume and the detected change resulting from at least one of resonant mid-infrared absorption, non-resonant mid-infrared absorption, and scattering by the particle may be used to determine a property of the particle. A wide range of properties of particles may be determined, wherein the particles may include living cells.

Apparatuses and methods for analyzing fluid samples are provided. For example, an example apparatus may include a fluid imaging chamber, at least one illumination source component, and an image sensor component. In some examples, the fluid imaging chamber comprises a flow channel for receiving a fluid sample. In some examples, the at least one illumination source component is configured to emit at least one light beam, and the at least one light beam is directed through the fluid sample in the flow channel from a top surface of the fluid imaging chamber. In some embodiments, the image sensor component is positioned under a bottom surface of the fluid imaging chamber and configured to generate digital holography image data of the fluid sample.

This lensless imaging system comprises a receiving support configured to receive a sample, a light source configured to emit a light beam illuminating the sample in an illumination direction, the light source including a diode and a diaphragm, the diaphragm being positioned between the diode and the receiving support in the lighting direction, and a matrix photodetector configured to acquire at least one image of the sample, each image being formed by radiation emitted by the illuminated sample and including at least one elementary diffraction pattern, the receiving support being positioned between the light source and the matrix photodetector in the illumination direction.

The system further comprises a light diffuser positioned between the diode and the diaphragm.

In some instances, an apparatus can include a light sensitive imaging sensor having a surface to receive a fluid sample, a body to be moved relative to the light sensitive imaging sensor and having a surface to touch a portion of the fluid sample, and a carrier to move the body toward the surface of the light sensitive imaging sensor to cause the surface of the body to touch the portion of the fluid sample, so that as the surface of the body touches the portion of the fluid, the surface of the body (i) is parallel to the surface of the light sensitive imaging sensor, and (ii) settles on top of the fluid sample independently of motion of the carrier.

Systems and methods are provided for counting particles in a fluid flow. In an aspect, coordinates of particles are obtained from video data of particles in a fluid, the video data made up of a sequence of image frames. The particle positions are linked in each pair of consecutive image frames of the video data. The linked particle positions are used to calculate particle trajectories through sequential image frames of the video data, and the particles are counted based on the particle trajectory. In another aspect, the particle positions within each image frame are transformed to estimated positions within a common coordinate frame. The estimated particle positions of a particle are grouped into a cluster center, and the particle count is calculated based on the cluster centers.

An imaging system for imaging a fluid sample includes a light source configured to generate a beam of light, an angled element disposed along an optical path of the beam of light, and a sample cartridge holder configured to receive a sample cartridge and configured to hold the sample cartridge in a first position in which an imaging region of the sample cartridge is disposed along the optical path. The system further includes a sensor configured to capture the beam of light after it passes through the angled element and the imaging region of the sample cartridge. The imaging region of the sample cartridge is configured to receive the sample fluid. A sample cartridge having a cover plate and a fluidics layer is also disclosed. The fluidics layer includes an opening, a fluid channel, and an imaging region configured to receive a whole blood sample.

Holograms of colloidal dispersions encode comprehensive information about individual particles' three-dimensional positions, sizes and optical properties. Extracting that information typically is computation-ally intensive, and thus slow. Machine-learning techniques based on support vector machines (SVMs) can analyze holographic video microscopy data in real time on low-power computers. The resulting stream of precise particle-resolved tracking and characterization data provides unparalleled insights into the composition and dynamics of colloidal dispersions and enables applications ranging from basic research to process control and quality assurance.

Stationary devices employing quadrature phase analysis light scattering are provided, to aid in the determination of the magnitude and polarity of electrophoretic mobility and zeta potential of particles in colloids. The devices use an optical quadrature interferometer with an electrophoresis sample chamber containing sample particles undergoing electrophoresis, the optical quadrature interferometer being configured to generate a quadrature signal. The phase of the quadrature signal may be analyzed at the frequency of the sample chamber electric field to estimate displacements and directions of the particles. The estimates can be used to determine a central value of the magnitude of the electrophoretic mobility, as well as its polarity. Particles having low electrophoretic mobility, or that may be adversely affected by high electric fields, can be analyzed, and constraints on vibration and light source coherence length may be relaxed. A phase modulator or frequency shifter is not required.

In one aspect, the present teachings provide a system for performing cytometry that can be operated in three operational modes. In one operational mode, a fluorescence image of a sample is obtained by exciting one or more fluorophore(s) present in the sample by an excitation beam formed as a superposition of a top-hat-shaped beam with a plurality of beams that are radiofrequency shifted relative to one another. In another operational mode, a sample can be illuminated successively over a time interval by a laser beam at a plurality of excitation frequencies in a scanning fashion. The fluorescence emission from the sample can be detected and analyzed, e.g., to generate a fluorescence image of the sample. In yet another operational mode, the system can be operated to illuminate a plurality of locations of a sample concurrently by a single excitation frequency, which can be generated, e.g., by shifting the central frequency of a laser beam by a radiofrequency. For example, a horizontal extent of the sample can be illuminated by a laser beam at a single excitation frequency. The detected fluorescence radiation can be used to analyze the fluorescence content of the sample, e.g., a cell/particle.

A method for lens-free imaging of a sample or objects within the sample uses multi-height iterative phase retrieval and rotational field transformations to perform wide FOV imaging of pathology samples with clinically comparable image quality to a benchtop lens-based microscope. The solution of the transport-of-intensity (TIE) equation is used as an initial guess in the phase recovery process to speed the image recovery process. The holographically reconstructed image can be digitally focused at any depth within the object FOV (after image capture) without the need for any focus adjustment, and is also digitally corrected for artifacts arising from uncontrolled tilting and height variations between the sample and sensor planes. In an alternative embodiment, a synthetic aperture approach is used with multi-angle iterative phase retrieval to perform wide FOV imaging of pathology samples and increase the effective numerical aperture of the image.