Devices and methods for using centripetal acceleration to drive fluid movement in a microfluidics system

A method for detecting gas or particles comprising an environmental sample, wherein the method comprises the steps of:

• a) Contacting the environmental sample with a sample inlet port of a microsystem platform of a centripetally-motivated fluid micromanipulation apparatus comprising a microsystem platform, wherein the microsystem platform comprises:
• i) a multiplicity of sample inlet ports, arranged concentrically around the center of the platform, wherein the sample ports comprise an air intake vent and a connecting funnel channel, wherein each of the sample inlet ports is operatively linked to
• ii) a multiplicity of microchannels arrayed radially away from the center of the platform, said microchannels being operatively linked to
• iii) a multiplicity of reagent reservoirs containing a reagent specific for the gas or particles to be detected, wherein release of the reagent from each of the reservoirs is controlled by a microvalve, wherein the microvalves are in electrical contact with a controller unit, and wherein the multiplicity of microchannels is also operatively linked to
• iv) a multiplicity of gas or particle detectors arranged peripherally around the outer edge of the microplatform,
• wherein movement of the environmental sample from the sample inlet port and through the microchannel, and movement of the reagent from the reagent from the reagent reservoir and through the microchannel is motivated by centripetal force generated by rotational motion of the micro system platform,
• b) placing the mcirosystem platform in a micromanipulation device,
• c) providing rotational motion to the microsystem platform for a time and at a velocity sufficient to motivate the gaseous or particulate environmental sample from the sample inlet port through the microchannel,
• d) opening each of the microvalves controlling the release of the reagent from the reagent reservoirs by generating a signal from the controlling unit, at a time and duration wherby the reagent moves into the microchannel and is mixed with the environmental sample,
• e) detecting the mixture of the environmental sample and the reagent or the gaseous or particulate component of the environmental sample directly in the gas or particle detection chamber, whereby each of the detectors detects a signal proportional to the amount of the gas or particulate present in the environmental sample, and
• f) recording the measurement of the amount of the gas or particulate in the environmental sample.

A method for determining a hematocrit value from a blood sample, the method comprising the steps of

• a) applying the blood sample to the proximal end of a microchannel of a microsystem platform of centripetally-motivated fluid micromanipulation apparatus comprising a micromanipulation device and a microsystem platform, wherein the microsystem platform comprises
• i) a radial array of microchannels having a diameter of about 100 μm wherein the microchannels are treated with heparin to prevent coagulation, and wherein the microchannels are open at one end proximal to the center of the disk, the apparatus also comprising a coherent light source and a recording means operatively connected thereto comprising the micromanipulation device, and wherein movement of the blood sample through the microchannel is motivated by centripetal force generated by rotational motion of the microsystem platform,
• b) placing the microsystems platform in a micromanipulation device,
• c) providing rotational motion to the Microsystems platform for a time and at a velocity sufficient to motivate the red blood cells comprising the blood sample to move along the extent of the microchannel,
• d) scanning the microchannel along its length with the coherent light source,
• e) detecting a change in light scatter at a position along the microchannel that defines a boundary between the red blood cells and blood plasma,
• f) recording the position of the boundary for each microchannel, and
• g) comparing the position of this boundary for each microchannel with a standard curve relating hematocrit values to the position of the boundary, and recording the hematocrit determined thereby.