Microfluidic flow sensor

Patent metadata

Field	Value
Publication number	US-10655994-B2
Application number	US-201515546327-A
Country	US
Kind code	B2
Filing date	Apr 30, 2015
Priority date	Apr 30, 2015
Publication date	May 19, 2020
Grant date	May 19, 2020

Abstract

An apparatus includes a microfluidic channel and a flow sensor along the microfluidic channel. The flow sensor includes a heat emitting resistor for connection to an electric current source, analytical parameter sensor and electronics. The heat emitting resistor has a resistance that varies in response to temperature. The electrical parameter sensor is to sense an electrical parameter of the heat emitting resistor that is based on the resistance of the heat emitting resistor. The electronics determine a flow based on the sensed electrical parameter.

First claim

What is claimed is:

1. An apparatus comprising:
a microfluidic channel; and
a flow sensor along the microfluidic channel, the flow sensor comprising:
a heat emitting resistor for connection to an electric current source, the heat emitting resistor having a resistance that varies in response to temperature;
an electrical parameter sensor to sense an electrical parameter of the heat emitting resistor that is based on the resistance of the heat emitting resistor;
a second heat emitting resistor having a resistance that varies in response to temperature;
a second sensor to sense an electrical parameter of the second heat emitting resistor that is based on the resistance of the second heat emitting resistor; and
electronics that determine at least one flow based on the sensed electrical parameter of the heat emitting resistor and the sensed electrical parameter of the second heat emitting resistor.

2. The apparatus of claim 1 further comprising:
a substrate supporting the microfluidic channel and the flow sensor; and
a fluid interaction component supported by the substrate to interact with fluid directed by the microfluidic channel.

3. The apparatus of claim 2 , when the fluid interaction component is selected from a group of fluid interaction components consisting of: a microfluidic branch channel stemming from the microfluidic channel; a microfluidic pump; a microfluidic valve; a microfluidic multi-mixer; a drop ejector; a thermal inkjet resistor; and a nozzle.

4. The apparatus of claim 1 ,
wherein the heat emitting resistor extends across the microfluidic channel in a path selected from a group of paths consisting of: diagonal, serpentine, wavy, zigzag, and square wave.

5. The apparatus of claim 1 further comprising:
a substrate underlying the heat emitting resistor; and
a thermal insulative layer between the substrate and the heat emitting resistor, the thermal insulative layer having a thermal conductivity of less than or equal to 1-2.5 W/m*° C.

6. The apparatus of claim 5 further comprising a second thermal insulative layer on opposite sides of the heat emitting resistor, wherein a top of the heat emitting resistor is exposed to fluid within the microfluidic channel, the second thermal insulative layer having a thermal conductivity of less than or equal to 0.3 W/m*° C.

7. The apparatus of claim 1 further comprising:
a substrate underlying the heat emitting resistor; and
a thermal insulative layer on opposite sides of the heat emitting resistor, wherein a top of the heat emitting resistor is exposed to fluid within the microfluidic channel, the thermal insulative layer having a thermal diffusivity less than a thermal diffusivity of the substrate.

8. The apparatus of claim 1 , wherein the heat emitting resistor comprises at least one material selected from a group of materials consisting of: aluminum, platinum, rhodium, copper, nickel, tantalum, tungsten, ruthenium, nickel chromium, copper nitride, silicon, polysilicon, germanium, carbon, graphing, tin oxide, zinc tin oxide, tantalum nitride, titanium nitride, magnesium oxide, rubidium oxide, vanadium oxide, and tungsten-silicon-nitride (WSi x N y ).

9. The apparatus of claim 1 comprising:
an array of spaced heat emitting resistors across a microfluidic channel, the array including the heat emitting resistor; and
sensors, each of the sensors to sense an electrical parameter of one of the heat emitting resistors that is based on the resistance of the heat emitting resistor.

10. The apparatus of claim 1 , wherein the heat emitting resistor has a length-to-width ratio of at least 5 to 1.

11. The apparatus of claim 1 , wherein the microfluidic channel extends along an axis along which the flow is directed and wherein the heat emitting resistor and the second heat emitting resistor extend across different portions of a width of the microfluidic channel perpendicular to the axis.

12. The apparatus of claim 11 , wherein the heat emitting resistor and the second heat emitting resistor are spaced apart from one another, end-to-end across the width of the microfluidic channel.

13. The apparatus of claim 12 , wherein the heat emitting resistor and the second heat emitting resistor extend along a line oblique to the axis.

14. The apparatus of claim 13 , further comprising a third heat emitting resistor spaced end-to-end from the second heat emitting resistor along the line oblique to the axis.

15. The apparatus of claim 13 , further comprising:
a substrate underlying the heat emitting resistor; and
a thermal insulative layer between the substrate in the heat emitting resistor, the thermal insulative layer having a thermal conductivity of less than or equal to 1-2.5 W/m*° C.

16. The apparatus of claim 15 further comprising a second thermal insulative layer on opposite sides of the heat emitting resistor, wherein a top of the heat emitting resistor is exposed to fluid within the microfluidic channel, the second thermal incident layer having a thermal conductivity of less than or equal to 0.3 W/m*° C.

17. The apparatus of claim 12 further comprising:
a substrate underlying the heat emitting resistor; and
a thermal insulative layer on opposite sides of the heat emitting resistor, wherein a top of the heat emitting resistor is exposed to fluid within the microfluidic channel, the thermal insulative layer having a thermal diffusivity less than a thermal diffusivity of the substrate.

18. The apparatus of claim 1 further comprising:
a third heat emitting resistor for connection to an electric current source; and
a third sensor to sense an electrical parameter of the third heat emitting resistor that is based upon resistance of the third heat emitting resistor, wherein the heat emitting resistor, the second heat emitting resistor and the third heat emitting resistor are spaced along an axis along which the flow is directed within the microfluidic channel.

19. The apparatus of claim 1 further comprising a third heat emitting resistor for connection to the electric current source, wherein the electronics determine a first flow along a first width portion of the microfluidic channel based on the sensed electrical parameter of the heat emitting resistor, wherein the electronics determine a second flow along a second width portion of the microfluidic channel based on the sensed electrical parameter of the second heat emitting resistor and wherein the electronics determine a direction of flow based upon the sensed electrical parameter of the third heat emitting resistor and one of the first heat emitting resistor and the second heat emitting resistor.

20. An apparatus comprising:
a microfluidic channel; and
a flow sensor along the microfluidic channel, the flow sensor comprising:
a heat emitting resistor for connection to an electric current source, the heat emitting resistor having a resistance that varies in response to temperature;
an electrical parameter sensor to sense an electrical parameter of the heat emitting resistor that is based on the resistance of the heat emitting resistor;

electronics that determine a flow based on the sensed electrical parameter;
electronic circuitry to transmit time-spaced electrical pulses across the heat emitting resistor; and
a pump, wherein the time-spaced electrical pulses are asynchronous with pumping by the pump.

21. The apparatus of claim 20 , wherein the pump comprises a bubble jet pump.

Assignees

• Hewlett Packard Development Co

Inventors

• Govyadinov Alexander
• Torniainen Erik D
• Kornilovich Pavel

Classifications

• G01F1/69

  of resistive type · CPC title

• B41J2/175

  Ink supply systems {; Circuit parts therefor} · CPC title

• B01L3/502746

  characterised by the means for controlling flow resistance, e.g. flow controllers, baffles or throttle valves · CPC title

• B01L2300/0627

  Sensor or part of a sensor is integrated · CPC title

• B01L2300/0887

  Laminated structure · CPC title