Fluid testing chip and cassette
A fluid testing cassette may comprise a microfluidic channel having a constriction and a micro-fabricated integrated sensor within the constriction. In one implementation, the constriction is less than or equal to 30 μm. In one implementation, the cassette further comprises a nozzle connecting the microfluidic channel to the discharge reservoir, wherein a thermal resistor expels fluid within the microfluidic channel into the discharge reservoir.
1. A fluid testing cassette comprising:
a chip comprising:
a microfluidic reservoir;
a microfluidic channel extending from the microfluidic reservoir and having:
a constriction having a width of no greater than 30 μm;
a cross-sectional area that is smaller than both adjacent regions of the microfluidic channel;
a first portion extending from the microfluidic reservoir and containing a thermal resistor; and
multiple additional portions branching from the first portion back to the microfluidic reservoir; and
a micro-fabricated integrated sensor within the constriction.
2. The fluid testing cassette of claim 1 further comprising a cassette body supporting the chip, the cassette body comprising a sample input port connected to the microfluidic reservoir.
3. The fluid testing cassette of claim 2 further comprising:
a reagent within the sample input port; and
a removable packaging completely enclosing the cassette body and the chip.
4. The fluid testing cassette of claim 2 further comprising a residence passage extending tortuously downward from the sample input port to microfluidic reservoir.
5. The fluid testing cassette of claim 2 , wherein the cassette body further comprises a discharge reservoir to receive fluid that has passed through the chip.
6. The fluid testing cassette of claim 5 , wherein the chip further comprises:
a nozzle connecting the microfluidic channel to the discharge reservoir; and
a thermal resistor to expel fluid through the nozzle into the discharge reservoir.
7. The fluid testing cassette of claim 1 , wherein the microfluidic channel comprises:
a second portion branching from the first portion back to the microfluidic reservoir, the second portion having the constriction containing the micro-fabricated integrated sensor; and
a third portion branching from the first portion back to the microfluidic reservoir, the third portion having a third constriction containing a third micro-fabricated integrated sensor.
8. The fluid testing cassette of claim 7 , wherein the first portion has an inlet from the microfluidic reservoir of a first width, wherein the second portion has an outlet to the reservoir of a second width greater than the first width and wherein the third portion has an outlet to the reservoir of a third width greater than the first width.
9. The fluid testing cassette of claim 1 , wherein the microfluidic channel comprises a second constriction containing a second micro-fabricated integrated sensor, wherein the constriction has a first width and wherein the second constriction has a second width different than the first width.
10. The fluid testing cassette of claim 1 further comprising a thermal resistor within the microfluidic channel to pump fluid through the microfluidic channel, wherein:
the thermal resistor has a length along the microfluidic channel;
the micro-fabricated integrated sensor is spaced from the thermal resistor along the microfluidic channel by a spacing of at least the length; and
the thermal resistor is spaced from the microfluidic reservoir along the microfluidic channel by a spacing of at least the length.
11. The fluid testing cassette of claim 1 , wherein the micro-fabricated integrated sensor has a length along the microfluidic channel, wherein the microfluidic channel has a second constriction, wherein the chip further comprises a second micro-fabricated integrated sensor within the second constriction and wherein the second micro-fabricated integrated sensor is spaced from the micro-fabricated integrated sensor by a distance of at least twice the length.
12. A fluid testing cassette comprising:
a sample input port to receive and direct a fluid sample to be tested to a microfluidic channel;
a side chamber to supply a fluid reagent to the sample input port;
the microfluidic channel comprising:
a first portion extending from the microfluidic reservoir and containing a thermal resistor in a constriction; and
at least one additional portion branching from the first portion back to the microfluidic reservoir;
per each of the additional portions, a micro-fabricated integrated sensor within a constriction;
a discharge reservoir;
a nozzle connecting the microfluidic channel to the discharge reservoir; and
a thermal resistor within the microfluidic channel to expel fluid in the microfluidic channel into the discharge reservoir.
13. The fluid testing cassette of claim 7 , wherein the second portion and the third portion branch off of opposite sides of the first portion.
14. The fluid testing cassette of claim 7 , wherein the second portion and the third portion have different dimensions.
15. The fluid testing cassette of claim 12 , wherein the sample input port comprises an open mouth to receive the fluid sample.
16. The fluid testing cassette of claim 12 , wherein the sample input port comprises a membrane to cover the sample input port.
17. The fluid testing cassette of claim 12 , wherein the discharge reservoir extends below the sample input port.
18. The fluid testing cassette of claim 12 , wherein:
the at least one additional portion comprises a second portion branching from the first portion back to the microfluidic reservoir; and
the microfluidic channel comprises a third portion branching from the second portion and returning to the second portion.
19. A fluid testing cassette comprising:
a cassette body;
a sample input port to receive and direct a fluid sample to be tested to a microfluidic chip;
a side chamber to supply a fluid reagent to the sample input port;
a flexible diaphragm over the side chamber to squeeze reagent into the sample input port upon depression of the flexible diaphragm;
the microfluidic chip, wherein the microfluidic chip comprises:
a microfluidic reservoir;
a microfluidic channel extending from the microfluidic reservoir comprising:
a first U-shaped portion extending from the microfluidic reservoir and containing a thermal resistor;
multiple additional U-shaped portions branching from the first portion back to the microfluidic reservoir; and
per each of the multiple additional U-shaped portions, a constriction having:
a cross-sectional area that is smaller than both adjacent regions; and
columns projecting between walls of the portion;
a micro-fabricated integrated sensor within each constriction;
a discharge reservoir enclosed within the cassette body;
a nozzle connecting the microfluidic channel to the discharge reservoir;
a discharge passage extending from the nozzle towards the discharge reservoir to inhibit reverse backflow; and
a thermal resistor within the microfluidic channel to expel fluid in the microfluidic channel into the discharge reservoir.
20. The fluid testing cassette of claim 19 , wherein the sample input port comprises a mouth formed on an elevated mound, a top surface of the elevated mound concave to match a surface of a finger.