Increasing the capture zone by nanostructure patterns
Techniques for increasing the capture zone in nano and microchannel-based polymer testing structures using concentric arrangements of nanostructures, such as nanopillars are provided. In one aspect, a testing structure for testing polymers is provided that includes a first fluid reservoir and a second fluid reservoir formed in an electrically insulating substrate; at least one channel formed in the insulating substrate that interconnects the first fluid reservoir and the second fluid reservoir; and an arrangement of nanostructures within either the first fluid reservoir or the second fluid reservoir wherein the nanostructures are arranged so as to form multiple concentric circles inside either the first fluid reservoir or the second fluid reservoir with each of the concentric circles being centered at an entry point of the channel. A method of analyzing a polymer using the testing structure is also provided.
1. A method of analyzing a polymer, the method comprising the steps of:
providing a testing structure having a first fluid reservoir and a second fluid reservoir interconnected by at least one nanochannel, an electrolyte solution within the first fluid reservoir, the second fluid reservoir and the nanochannel, and an arrangement of nanostructures within the first fluid reservoir, wherein the first fluid reservoir has a square shape with four sides and wherein the at least one nanochannel connects with the first fluid reservoir along one of the sides, wherein the nanostructures are arranged so as to form multiple concentric circles inside the first fluid reservoir with each of the concentric circles being centered at an entry point of the nanochannel;
placing the polymer within the first fluid reservoir;
applying a voltage to the first fluid reservoir and the second fluid reservoir to create an electrical force to move the polymer through the arrangement of nanostructures which directs the polymer into the nanochannel by way of the concentric circles being centered at the entry point of the nanochannel; and
monitoring ionic current changes in the electrolyte solution as the polymer passes through the nanochannel to obtain ionic current data for one or more constituent components of the polymer.
2. The method of claim 1 , wherein the polymer comprises a linear polymer selected from the group consisting of: single stranded DNA, double stranded DNA, single stranded RNA, double stranded RNA, and a peptide.
3. The method of claim 1 , wherein the nanochannel has a round or square cross-sectional shape with at least one dimension that is from about 1 nanometer to about 100 nanometers and ranges therebetween, and a length of from about 100 nanometers to about 5 micrometers and ranges therebetween.
4. The method of claim 1 , wherein the nanostructures comprise nanopillars which each have a round, triangular, or square cross-sectional shape.
5. The method of claim 1 , wherein all of the nanostructures in the testing structure have a same shape and same dimensions as one another.
6. The method of claim 1 , wherein the nanochannel has a depth D and each of the nanostructures has a same height h, and wherein D=h.
7. The method of claim 1 , wherein the nanochannel has a round cross-section with a radius r 0 and wherein a number of the nanostructures at a distance r from the entry point of the channel is r/r 0 .
8. The method of claim 1 , wherein the voltage is applied to the first fluid reservoir and the second fluid reservoir via a first electrode in the first fluid reservoir and a second electrode in the second fluid reservoir, and wherein the ionic current changes in the electrolyte solution are monitored via an ammeter located in circuit with the first electrode and the second electrode.
9. The method of claim 8 , wherein the voltage is generated by a voltage source that is located in circuit with the first electrode, the second electrode, and the ammeter.