A method for detecting the concentration of particles in a fluid is disclosed. The method comprises the steps of: S1: introducing a pure fluid into a detection device to obtain a scatter background noise value U noise output by the detection device; S2: introducing a fluid to be detected into the detection device, obtaining scatter signals output by the detection device, and obtaining voltage signals of standard particles; S3: sampling signals of the fluid in a certain period of time, extracting effective signals, carrying out threshold value analysis on the effective signals Ux obtained by sampling, and obtaining the number of particles present in the period of time; and S4: obtaining the concentration of the particles in the fluid according to the number of particles in S3. According to this method, the accuracy in calculation of the concentration of particles in a fluid can be effectively improved.

A method of partitioning droplets from a fluid reservoir containing particles provides a non-Poissonian distribution of dispensed droplets containing a desired number of particles. The method constitutes a method of operating an electrowetting on dielectric (EWOD) device including the steps of: inputting a fluid reservoir containing particles into the EWOD device; performing an electrowetting operation to dispense a plurality of dispensed droplets from the fluid reservoir; interrogating each droplet with a detector and determining whether each dispensed droplet has a desired number of particles; selecting dispensed droplets that contain the desired number of particles and performing an electrowetting operation to move the selected dispensed droplets to a reaction area on the EWOD device; and rejecting dispensed droplets that do not contain the desired number of particles and performing an electrowetting operation to move the rejected dispensed droplets to a holding area on the EWOD device that is different and spaced apart from the reaction area. The selected droplets may be combined, including with or without a portion of the rejected droplets and/or additional reagent, into a larger reaction droplet that may be used in subsequent reaction protocols.

A differential emissivity imaging device for measuring evaporable particle properties can include a heated plate, a thermal camera, a memory device, and an output interface. The heated plate can have an upper surface oriented to receive falling evaporable particles. The evaporable particles have a particle emissivity and the upper surface has a plate surface emissivity. The thermal camera can be oriented to produce a thermal image of the upper surface. A memory device can include instructions that cause the imaging device to calculate a mass of the individual evaporable particle via heat conduction using a calculated surface area and an evaporation time.

Systems and methods for measuring the properties (e.g., mechanical properties) of particles such as biological entities, in a fluidic channel(s) are generally provided. In some embodiments, the systems and methods comprise measuring an acoustic scattering of single particles. For example, a single particle (e.g., a biological entity) may be flowed in a suspended fluidic channel (e.g., a suspended microfluidic channel) and the fluidic channel is oscillated at or near a (mechanical) resonant frequency (e.g., at a second or higher bending mode) of the suspended fluidic channel. In some cases, an acoustic scattering signal (e.g., the change in resonant frequency of the fluidic channel as the particle flows along a longitudinal axis of the channel) may correspond to a property (e.g., a mechanical property, a cross-linking density, a transport rate of small molecules into/out of the particle) of the particle. In certain embodiments, the systems and methods comprise determining a node deviation due to a single particle (or node deviations for a plurality of particles).

Disclosed herein is a device for characterizing a biological sample or an airborne sample. According to embodiments of the present disclosure, the device comprises an electrospray source, a mass analyzer, a charge detector, and optionally, an ion guide. The present device is useful in analyzing the particle population in the biological or airborne sample based on the mass to charge (m/z) ratio and the charge (z) of each particle. Also disclosed herein are the methods of making a diagnosis of cancer by use of the present device, and methods of determining the mass distribution of particles in an airborne sample.

Systems and methods for measuring the properties (e.g., masses, weights, densities, etc.) of particles, such as biological entities, in a fluidic channel are generally provided. In some embodiments, the systems and methods comprise a plurality of suspended microchannel resonators (SMRs) configured to operate simultaneously. A particle or a plurality of particles may be dissolved or suspended in a fluid, whereby the fluid is flowed through an inlet (e.g., an inlet channel) that is fluidically connected in parallel and in fluid communication with at least one SMR (e.g. at least one SMR, at least two SMRs, at least four SMRs, at least 8, at least 16 SMRs). Fluid containing a particle or particles may flow into the plurality of SMRs, which may oscillate at a certain frequency (e.g., a resonance frequency). As particles pass through the SMR(s), the mass of particle may cause a change in the resonance frequency, the change in frequency which may be read out via embedded piezoresistors. The SMR may comprise a cantilever, where shifts in the resonance frequency of each cantilever can be tracked independently and whereby frequency-multiplexing allows each cantilever to be continuously driven at the resonance frequency using a single actuation channel and a single detection channel. This may provide a precise, statistically-relevant property determination of the particles within the fluid (e.g., the mass of the particles).

Methods for determining the hardness and/or ductility of a material by compression of the material are provided as a first aspect of the invention. Typically, compression is performed on multiple sides of a geologic material sample in a contemporaneous manner. Devices and systems for performing such methods also are provided. These methods, devices, and systems can be combined with additional methods, devices, and systems of the invention that provide for the analysis of compounds contained in such samples, which can indicate the presence of valuable materials, such as petroleum-associated hydrocarbons. Alternatively, these additional methods, devices, and systems can also stand independently of the methods, devices, and systems for analyzing ductility and/or hardness of materials.