Microfluidic devices with integrated resistive heater electrodes including systems and methods for controlling and measuring the temperatures of such heater electrodes
The invention relates to methods and devices for control of an integrated thin-film device with a plurality of microfluidic channels. In one embodiment, a microfluidic device is provided that includes a microfluidic chip having a plurality of microfluidic channels and a plurality of multiplexed heater electrodes, wherein the heater electrodes are part of a multiplex circuit including a common lead connecting the heater electrodes to a power supply, each of the heater electrodes being associated with one of the microfluidic channels. The microfluidic device also includes a control system configured to regulate power applied to each heater electrode by varying a duty cycle, the control system being further configured to determine the temperature of each heater electrode by determining the resistance of each heater electrode.
1. A system comprising:
a multiplex circuit comprising a plurality of multiplexed heater electrodes sharing a common lead connecting the electrodes to a power supply;
a controller having instruction for:
sequentially measuring the combined series resistances for N number of distinct sensor pairs, such that each of the plurality of sensors is included in at least one of the measured sensor pairs, wherein N is the number of sensors in the plurality of sensors, and the measured sensor pairings are such that the individual resistance of each of the plurality of sensors may be determined; and
determining by a processor the individual resistance of at least one of the plurality of sensors based upon the measured combined series resistances.
2. The system of claim 1 , wherein the instruction of determining the resistance of at least one of the plurality of sensors comprises: defining a first matrix corresponding to the measured combined series resistances; defining a second matrix having rows and columns such that each column corresponds to a sensor in the network and each row represents a measured sensor pair configuration; generating an inverse matrix of the second matrix; and multiplying the inverse of the second matrix by the first matrix.
3. The system of claim 2 , wherein the second matrix is defined by linearly independent equations such that the second matrix is of full rank.
4. The system of claim 1 , wherein measuring a combined series resistance of a sensor pair comprises: electrically isolating the sensor pair from the other sensors in the plurality of sensors; applying a source voltage or current to a first terminal electrically coupled to a first sensor of the sensor pair, measuring an output voltage at a second terminal electrically coupled to a second sensor of the sensor pair.
5. The system of claim 4 , further comprising a control unit, wherein the measurements are performed in accordance with timing instructions supplied by the control unit.
6. The system of claim 1 , further comprising a microfluidic device, wherein the multiplexed sensor network is a component of the microfluidic device.
7. The system of claim 1 , wherein the sensors are in thermal communication with a fluidic channel.
8. The system of claim 1 , wherein the sensors are resistance temperature detectors.
9. The system of claim 1 , further comprising: generating a feedback signal based upon either the equivalent resistance of a series combination of sensors or the resistance of an individual sensor; and transmitting the feedback signal to a control unit configured to provide closed-loop thermal control.
10. The system of claim 9 , wherein the feedback signal describes the status of a biological process.