Claims:1. A system (100) for trapping and manipulating magnetic particles (112), the system comprising:
a pair of conductors (108) electrically coupled with a current source (102);
a conductive ring (110) electrically coupled at a first end of the pair of conductors 108, and being configured to be positioned above one or more magnetic particles (112),
wherein the conductive ring (110) is configured to trap the one or more magnetic particles (112) when a current having pre-defined parameters is flown through the conductive ring (110) from the pair of conductors (108).
2. The system (100) as claimed in claim 1, wherein the pair of conductors (108) is electrically coupled, at a second end, in a cantilever arrangement with a pre-defined attributes, with a substrate (104) electrically coupled with the current source (102).
3. The system (100) as claimed in claim 1, wherein an axial force of interaction between the one or more magnetic particles (112) and the conductive ring (110) causes a deformation in the cantilever arrangement of the pair of conductors (108).
4. The system (100) as claimed in claim 3, wherein the system (108) comprises a position detecting unit to measure the deformation of the cantilever arrangement of the pair of conductors (108).
5. The system (100) as claimed in claim 3, wherein the measurement of the deformation corresponds to a position of the one or more magnetic particle (112) along an axis of the conductive ring (110).
6. The system (100) as claimed in claim 3, wherein the position detecting unit system comprises a laser source (116) focusing at an end of the conductive ring (110), and a processor.
7. The system (100) as claimed in claim 3, wherein the pre-defined attributes comprises any or combination of length, width, thickness, and stiffness.
8. The system (100) as claimed in claim 1, wherein the pre-defined parameters comprise any or combination of amplitude, phase, and frequency.
, Description:TECHNICAL FIELD
[0001] The present disclosure relates to the field of magnetic tweezers, and more particularly the present disclosure relates to a system for trapping and manipulating the magnetic particles.

BACKGROUND OF THE INVENTION
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] Optical tweezers are scientific instruments that are used to hold microscopic objects such as nanoparticles. Conventionally, the optical tweezers include highly focused laser beam for providing attractive or repulsive force on the nanoparticles. The optical tweezers use principle of optical trapping for holding the nanoparticles. Magnetic particles are employed as manipulators in magnetic tweezers systems, where they are subjected to magnetic forces in order to get them to manipulate non-magnetic objects. Magnetic tweezers are widely used in molecular biology, cell biology and polymer sciences, in applications such as unfolding of DNA and other macro-molecules, characterization of intracellular visco-elastic properties, and in force spectroscopy.
[0004] Magnetic tweezers have some important advantages over optical tweezers, such as in the specificity of interaction, and absence of photo-damage to the manipulated object. However, unlike optical tweezers, the magnetic particle can’t be stably trapped in 3-D and requires the use of visual feedback for trapping. This is an important drawback since visual measurement of particle position can be compromised either partially or completely when the particle is buried inside a cell, or when it is desired to be guided into concave features of a sample.
[0005] There is, therefore, a requirement of a magnetic tweezer that is capable of trapping the magnetic particle in 3-D without any feedback control.

OBJECTS OF THE PRESENT DISCLOSURE
[0006] It is an object of the present disclosure to provide a magnetic tweezer capable of trapping the magnetic particle without feedback control.
[0007] It is an object of the present disclosure to provide a magnetic tweezer capable of sensing axial position of the magnetic particle in 3-D.

SUMMARY
[0008] The present disclosure relates to the field of magnetic tweezers, and more particularly the present disclosure relates to a system for trapping and manipulating the magnetic particles.
[0009] An aspect of the present disclosure relates to a system for trapping and manipulating magnetic particles. The system includes a pair of conductors electrically coupled with a current source. A conductive ring electrically coupled at a first end of the pair of conductors, and being configured to be positioned above one or more magnetic particles. The conductive ring is configured to trap the one or more magnetic particles when a current having pre-defined parameters is flown through the conductive ring from the pair of conductors.
[0010] In an aspect, the pair of conductors may be electrically coupled at a second end, in a cantilever arrangement with a pre-defined attributes, with a substrate electrically coupled with the current source.
[0011] In an aspect, an axial force of interaction between the one or more magnetic particles and the conductive ring may cause a deformation on the cantilever arrangement of the pair of conductors.
[0012] In an aspect, the system may include a position detecting unit to measure the deformation of the cantilever arrangement of the pair of conductors.
[0013] In an aspect, the measurement of the deformation corresponds to a position of the one or more magnetic particle along an axis of the conductive ring.
[0014] In an aspect, the position detecting unit system may include combination of a laser source focusing at an end of the conductive ring, and a processor.
[0015] In an aspect, the pre-defined attributes may include combination of length, width, thickness, and stiffness.
[0016] In an aspect, the pre-defined parameters may include combination of amplitude, phase, and frequency.
[0017] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF DRAWINGS
[0018] The accompanying drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.
[0019] FIG. 1 illustrates an exemplary diagram of a system for trapping magnetic particles, according to an embodiment of present disclosure.
[0020] FIG. 2A illustrates initial location of the magnetic particle, FIG. 2B illustrates particle just before it was trapped, and FIG. 2C illustrates trapped magnetic particle in 3-D at a frequency of , according to an embodiment of present disclosure.
[0021] FIG. 3A illustrates a trapped magnetic particle, FIG. 3B illustrates the trapped magnetic particle when a surface below the magnetic particle is retracted, FIG. 3C illustrates trapped magnetic particle when the surface below the magnetic particle is back under the trapped magnetic particle, and FIG. 3D illustrates measured trajectory of the particle as the micro-ring executed circular motion of radius about 20 micro-meter, according to an embodiment of present disclosure.
[0022] FIG. 4A illustrates a dependence of first harmonic of deflection of pair of conductors on the steady-state value of mean position of the magnetic particle, for different magnitudes of constant force experienced by the particle, FIG. 4B illustrates dependence of the measured deformation voltage as function of the position of the particle from a center of the conductive ring, according to an embodiment of present disclosure.

DETAILED DESCRIPTION
[0023] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0024] If the specification states a component or feature “may”, “can”, “could”, or “might” be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic.
[0025] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0026] The present disclosure relates to the field of magnetic tweezers, and more particularly the present disclosure relates to a system for trapping and manipulating the magnetic particles.
[0027] In an embodiment the present disclosure elaborated upon a system for trapping and manipulating magnetic particles. The system includes a pair of conductors electrically coupled with a current source. A conductive ring electrically coupled at a first end of the pair of conductors, and being configured to be positioned above one or more magnetic particles. The conductive ring is configured to trap the one or more magnetic particles when a current having pre-defined parameters is flown through the conductive ring from the pair of conductors.
[0028] In an embodiment, the pair of conductors can be electrically coupled at a second end, in a cantilever arrangement with a pre-defined attributes, with a substrate electrically coupled with the current source.
[0029] In an embodiment, an axial force of interaction between the one or more magnetic particles and the conductive ring can cause a deformation on the cantilever arrangement of the pair of conductors.
[0030] In an embodiment, the system can include a position detecting unit to measure the deformation of the cantilever arrangement of the pair of conductors.
[0031] In an embodiment, the measurement of the deformation corresponds to a position of the one or more magnetic particle along an axis of the conductive ring.
[0032] In an embodiment, the position detecting unit system can include combination of a laser source focusing at an end of the conductive ring, and a processor.
[0033] In an embodiment, the pre-defined attributes can include combination of length, width, thickness, and stiffness.
[0034] In an embodiment, the pre-defined parameters can include combination of amplitude, phase, and frequency.
[0035] FIG. 1 illustrates an exemplary diagram of a system for trapping magnetic particles, according to an embodiment of present disclosure.
[0036] As illustrated, the system 100 can include a pair of conductors 108 that can be electrically coupled with a current source 102. A conductive ring 110 can be electrically coupled at a first end of the pair of conductors 108, and being configured to be positioned above one or more magnetic particles 112. The radius of the conductive ring 110 can be chosen to be larger than the size of the magnetic particles 112, but small enough that the gradients in magnetic field generated by the conductive ring 110 are high. The magnetic particles 112 can be ferromagnetic micro-particles. A magnetic moment of the magnetic particles 112 can be aligned along an axis of the conductive ring 110 using an external magnetic field Bz0.
[0037] In an embodiment, the conductive ring 110 can be configured to trap the magnetic particles 112 when a current having pre-defined parameters is flown through the conductive ring 110 from the pair of conductors 108. The current source 102 can be configured to produce a sinusoidal current with a predetermined amplitude, phase, and frequency. The pair of conductors 108 can be electrically coupled at a second end, in a cantilever arrangement with a predefined attributes with a substrate 104 that can be electrically coupled with the current source 102. The cantilever arrangement of the pair of conductors 108 can have a predefined attributes that can include any or combination of length, width, thickness, and stiffness. The conductive ring 110 can be suspended away from the substrate 104 with the cantilever arrangement of the pair of conductors 108. The length and cross-section of the pair of conductors 108 can be chosen to ensure that the mechanical compliance is adequately high, but yet the rise in temperature, owing to joule heating, is low.
[0038] In an embodiment, the cantilever arrangement of the pair of conductors 108 can act as a force sensor whole deformation can be measured to detect a position of the magnetic particles 112 along the axis of the conductive ring 108. The pair of conductor 108 along with the conductive ring 110 can act as an actuator sensor. An axial force of interaction between the magnetic particles 112 and the conductive ring 110 can cause deformation on the cantilever arrangement of the pair of conductors 108. The system 100 can include a position detecting unit to measure the deformation of the cantilever arrangement of the pair of conductors 108. The measurement of the deformation of the cantilever arrangement of the pair of conductors 108 can corresponds to a position of the magnetic particles 112 along the axis of the conductive ring 108. Once the magnetic particle 112 is trapped, the magnetic particle 112 can be manipulated with the conductive ring 110. The magnetic particle 112 can follow a trajectory of the conductive ring 108 after being trapped.
[0039] In an embodiment, the position detecting unit system can include a laser source 116, and a measurement system 114. The measurement system 114 can further include a receiver (not shown) and a processor (not shown). The laser 116 can focus the laser light at an end of the conductive ring 110, and after reflection from the conductive ring 110, the laser light can be received by the receiver. The processor can calculate the deformation in the cantilever arrangement of the pair of conductors 108, which can correspond to the position of the magnetic particles 112 along the axis of the conductive ring 108. The pre-defined parameters of the current flown through the conductive ring 108 can include combination of amplitude, phase, and frequency.
[0040] FIG. 2A illustrates initial location of the magnetic particle, FIG. 2B illustrates particle of diameter 18µm just before it was trapped, and FIG. 2C illustrates trapped magnetic particle in 3-D at a frequency of , according to an embodiment of present disclosure.
[0041] FIG. 3A illustrates a trapped magnetic particle, FIG. 3B illustrates the trapped magnetic particle when a surface below the magnetic particle is retracted, FIG. 3C illustrates trapped magnetic particle when the surface below the magnetic particle is back under the trapped magnetic particle, and FIG. 3D illustrates measured trajectory of the particle as the micro-ring executed circular motion of radius about 20 micro-meter, according to an embodiment of present disclosure.
[0042] While experiment, a micro-ring of mean diameter was employed to trap permanent-magnet particles (MQP S-11-9, an alloy of Neodymium, Iron and Boron) of sizes in the range to . The length, width and thickness of both the cantilever beams (also referred as pair of conductors 108, herein) were , , respectively and the overall stiffness was . The micro-particles (also referred as magnetic particles 112, herein) were magnetized to saturation and placed within deionized water. The value of external magnetic field (Bz0) was about 40 G. A current of 100 mA was applied to the conductive ring 110. The micro-particles were magnetized to saturation and placed within deionized water. The micro-ring (also referred as conductive ring 110, herein) was initially positioned such that the magnetic particle 112 was visible within its boundary. Subsequently, the vertical offset between the particle and the conductive ring 110 was reduced to a value less than the radius of the ring. Finally, the actuation current of amplitude was applied, and the frequency was swept. In a certain range of frequencies, the particles were observed to get trapped in 3-D. FIGs. 2A-2C illustrates the step of trapping magnetic particle of 18 micrometer with the help of proposed system.
[0043] As illustrated, the magnetic particle 112 once trapped can follow trajectory of the micro-ring 110. FIG. 3A illustrates trapped magnetic particle about 350 µm above surface under the magnetic particle 112. One the magnetic particle 112 was trapped, the surface under the magnetic particle 112 was retracted to make sure the magnetic particle was trapped as illustrated in FIG. 3B, and the surface was again extended under the magnetic particle 112 later on, as shown in FIG. 3C. Once the magnetic particle 112 was trapped, the conductive ring was moved in a trajectory and the magnetic particle 112 followed the almost same trajectory as that of the conductive ring 110, as shown in FIG. 3D.
[0044] FIG. 4A illustrates a dependence of first harmonic of deflection of pair of conductors on the steady-state value of mean position of the magnetic particle, for different magnitudes of constant force experienced by the particle, FIG. 4B illustrates dependence of the measured deformation voltage as function of the position of the magnetic particle from a center of the conductive ring, according to an embodiment of present disclosure.
[0045] As illustrated, in general, motion of a parametrically excited magnetic particle in an environment with damping includes a component close to the excitation frequency, superposed on motion at much lower frequencies, with the latter component termed as secular motion. Together they contribute to a force on the conductive ring that is dependent on the instantaneous position of the particle. Since the applied magnetic field oscillates at the frequency, the secular motion of the particle determines the first harmonic of the pair of conductors deformation. FIG. 4A illustrates plots the dependence of on the steady-state value of , for different magnitudes of constant force experienced by the particle. It shows that the two are proportional to each other. In other words, enables estimation of , and by employing a lock-in amplifier to measure the deflection or deformation of the cantilever arrangement of pair of conductors 108, at the frequency , it is possible to infer the latter.
[0046] As shown in the FIG. 4A, a sensitivity of estimation is proportional to the amplitude of the applied excitation current. It is worth noting that even when the particle is tethered to a substrate, would be proportional to the mean position of the magnetic particle, as shown in the FIG. 4B. In the experiment, the magnetic particle was trapped in-plane on the surface at 2.5 kHz rather than in 3-D and the deflection of the actuator-sensor (also referred as pair of conductors 108, herein) at frequency was measured as the separation between the magnetic particle 112 and the conductive ring 110 was varied. FIG. 4B shows almost linear relationship, and thus measured deflection can be employed to infer .
[0047] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

ADVANTAGES OF THE INVENTION
[0048] The proposed invention provides a magnetic tweezer capable of trapping the magnetic particle without feedback control.
[0049] The proposed invention provides a magnetic tweezer capable of sensing axial position of the magnetic particle in 3-D.