System and method for scalable real-time micro-object position control with the aid of a digital computer
The system and method described below allow for real-time control over positioning of a micro-object. A movement of at least one micro-object suspended in a medium can be induced by a generation of one or more forces by electrodes proximate to the micro-object. Prior to inducing the movement, a simulation is used to develop a model describing a parameter of an interaction between each of the electrodes and the micro-object. A function describing the forces generated by an electrode and an extent of the movement induced due to the forces is generated using the model. The function is used to design closed loop policy control scheme for moving the micro-object towards a desired position. The position of the micro-object is tracked and taken into account when generating control signals in the scheme.
1. A system for scalable real-time micro-object position control with the aid of a digital computer, comprising:
at least one processor configured to execute computer-executable code and further configured to:
obtain one or more parameters of a system for positioning of at least one micro-object, the system comprising a plurality of electrodes, the electrodes configured to induce a movement of the micro-object when the micro-object is suspended in a fluid proximate to the electrodes upon a generation of one or more forces by the electrodes;
model a capacitance of an interaction between each of the electrodes and the micro-object as a function of a distance between that electrode and the micro-object using the system parameters;
obtain a position of the micro-object within the fluid;
obtain using the modeled capacitance a further function describing a relationship between the forces generated by one of the electrodes for a predefined period of time and an extent of the movement induced by the forces generated by the one electrode, comprising:
map a plurality of values for the one or more forces generated by the one electrode to the extent of the movement of the micro-object induced by the generation of each of the voltage values; and
derive the further function from the mappings; and
generate a control signal for each of the electrodes, the control signal comprising a command to generate one or more of the forces for the predefined period of time by that electrode, using the obtained position, the further function, and a desired location of the micro-object.
2. A system according to claim 1 , wherein the electrodes are spiral electrodes and are comprised in an electrode unit.
3. A system according to claim 1 , wherein the electrodes are periodically spaced.
4. A system according to claim 1 , the at least one processor further configured to:
perform a plurality of simulations of the interaction parameters at a plurality of values of the distance, wherein the modeling is done based on the simulations.
5. A system according to claim 1 , the at least one processor further configured to:
apply the control signals to the electrodes, wherein the electrodes generate the one or more forces commanded by the control signals upon the application and induce the movement of the micro-object;
identify a further position of the micro-object following the application of the control signals to the electrodes; and
generate further control signals for the electrodes using the interaction parameter, the further position of the micro-object, and the desired position of the micro-object following the application.
6. A system according to claim 5 , the at least one processor further configured to:
receive raw data captured by a high-speed, high-resolution camera monitoring the micro-object, the raw data having been captured before and after the application of the control signals;
convert the raw data into a plurality of images using a frame grabber;
perform background extraction on the images converted from the raw data captured before the application of the control signals;
identify foreground components in at least one of the images converted from the raw data captured after the application of the signal using a result of the background extraction;
identify the foreground components whose size is greater than or equals to a predefined size; and
perform a template matching algorithm in a neighborhood associated with the foreground components to identify the position of the micro-object.
7. A system according to claim 5 , the at least one processor further configured to:
apply a morphological opening to the foreground components to identify the foreground components whose size is greater than or equal to the predefined size.
8. A system according to claim 5 , the at least one processor further configured to:
define a window around the identified position,
wherein the template matching algorithm is run in a neighborhood defined by the window to determine a subsequent position of the micro-object.
9. A system according to claim 1 , the at least one processor further configured to:
perform a plurality of simulations to obtain the mappings.
10. A method for scalable real-time micro-object position control with the aid of a digital computer, comprising the steps of:
obtaining one or more parameters of a system for positioning of at least one micro-object, the system comprising a plurality of electrodes, the electrodes configured to induce a movement of the micro-object when the micro-object is suspended in a fluid proximate to the electrodes upon a generation of one or more forces by the electrodes;
modeling a capacitance of an interaction between each of the electrodes and the micro-object as a function of a distance between a location of that electrode and a location of the micro-object using the system parameters;
obtaining a position of the micro-object within the fluid;
obtaining using the modeled capacitance a further function describing a relationship between the forces generated at one of the electrodes for a predefined period of time and an extent of the movement induced by the forces generated by the one electrode, comprising:
mapping a plurality of values for the one or more forces generated by the one electrode to the extent of the movement of the micro-object induced by the generation of each of the voltage values; and
deriving the further function from the mappings; and
generating a control signal for each of the electrodes, the control signal comprising a command to generate one or more of the forces for the predefined period of time by that electrode, using the obtained position, the further function, and a desired location of the micro-object,
wherein the steps are performed by a computer.
11. A method according to claim 10 , wherein the electrodes are spiral electrodes and are comprised in an electrode unit.
12. A method according to claim 10 , wherein the electrodes are periodically spaced.
13. A method according to claim 10 , further comprising:
performing a plurality of simulations of the interaction parameters at a plurality of values of the distance, wherein the modeling is done based on the simulations.
14. A method according to claim 10 , further comprising:
applying the control signals to the electrodes, wherein the electrodes generate the one or more forces commanded by the control signals upon the application and induce the movement of the micro-object;
identifying a further position of the micro-object following the application of the control signals to the electrodes; and
generating further control signals for the electrodes using the interaction parameter, the further position of the micro-object, and the desired position of the micro-object following the application.
15. A method according to claim 14 , further comprising:
receiving raw data captured by a high-speed, high-resolution camera monitoring the micro-object, the raw data having been captured before and after the application of the control signals;
converting the raw data into a plurality of images using a frame grabber;
performing background extraction on the images converted from the raw data captured before the application of the control signals;
identifying foreground components in at least one of the images converted from the raw data captured after the application of the signal using a result of the background extraction;
identifying the foreground components whose size is greater than or equals to a predefined size; and
performing a template matching algorithm in a neighborhood associated with the foreground components to identify the position of the micro-object.
16. A method according to claim 15 , further comprising:
applying a morphological opening to the foreground components to identify the foreground components whose size is greater than or equal to the predefined size.
17. A method according to claim 15 , further comprising:
defining a window around the identified position,
wherein the template matching algorithm is run in a neighborhood defined by the window to determine a subsequent position of the micro-object.
18. A method according to claim 10 , comprising:
performing a plurality of simulations to obtain the mappings.