Preventing adhesion between nanostructures

A device for Surface Enhanced Raman Scattering (SERS). The device includes a plurality of nanostructures protruding from a surface of a substrate, a SERS active metal disposed on a portion of said plurality of nanostructures, and a low friction film disposed over the plurality of nanostructures and the SERS active metal. The low friction film is to prevent adhesion between the plurality of nanostructures.

BACKGROUND

Surface Enhanced Raman Scattering (SERS) is a technique using Raman scattering for enhancing the detection of molecular species through the excitation of Plasmon modes and their coupling to molecular vibrational modes. In other words, Raman scattering is the inelastic scattering of photons that can provide vibrational fingerprints of molecules.

Nanostructures on a substrate where the detection of molecular species takes place affects the Raman scattering. In particular, when the nanostructures are adhered together, the Raman scattering can be negatively affected.

DESCRIPTION

Reference will now be made in detail to examples of the present technology, examples of which are illustrated in the accompanying drawings. While the technology will be described in conjunction with various example(s), it will be understood that they are not intended to limit the present technology to these examples. On the contrary, the present technology is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the various examples as defined by the appended claims.

Furthermore, in the following description of examples, numerous specific details are set forth in order to provide a thorough understanding of the present technology. However, the present technology may be practiced without these specific details. In other instances, well known methods, procedures, components, and circuits have not been described in detail as not to unnecessarily obscure aspects of the present examples.

FIG. 1depicts device100for SERS, in accordance with an example of the present technology. Device100includes substrate110, nanostructures120-122, SERS active metal130-132and low friction film140.

Nanostructures120-122are disposed on substrate110. It should be appreciated that any number of nanostructures are disposed in various orientations on substrate110. In various examples, the shapes of the nanostructures120-122can be, but are not limited to, conical, cylindrical and the like. It should be appreciated nanostructures120-122can be any shape that facilitates in the enhancement of Raman scattering. In one example, nanostructures120-122are flexible, such that nanostructures120-122may come into contact with neighboring nanostructures.

SERS active metals130-132are disposed at least on a portion of nanostructures120-122. In general, SERS active metals are metals that help provide for the enhancement of Raman scattering during SERS.

In one example, SERS active metals130-132are disposed on a tip portion of nanostructures120-122. It should be appreciated that a SERS active metal can be disposed on nanostructures in any fashion to facilitate in enhancing Raman scattering. For example, SERS active metal can be deposited as a uniform thin layer on all of the nanostructures. SERS active metals130-132, can be, but are not limited to, silver, gold, platinum or copper.

Low friction film140is to prevent adhesion between nanostructures120-122. In contrast, in conventional technology, oftentimes nanostructures in close proximity to one another adhere to one another. Accordingly, SERS is negatively affected. Moreover, long term use of SERS devices is also negatively affected.

The adhesion between nanostructures is often due to van der Waals forces between the nanostructures. Additionally, nanostructures may be brought together via microcapillary forces.

Low friction film140is disposed over SERS active metals130-132and nanostructures120-122. In one example, low friction film140has a thickness of 2 nanometers or less.

Low friction film140can be, but is not limited to, CF4, C2F4, and diamond-like carbon. It should be appreciated that low friction film is any film that includes low interaction forces and is able to prevent adhesion between nanostructures. In particular, low friction film is an film that prevents adhesion due to van der Waals forces.

Low friction film140may be deposited on nanostructures120-122and SERS active metals130-132in a variety of ways. For example, low friction film140may be deposited by, but not limited to, vapor deposition, chemical vapor deposition (CVD), plasma CVD, molecule self assembly, atomic layer deposition, and the like.

FIG. 2depicts device200for SERS, in accordance with an example of the present technology. Device200is similar to device100, as described above. However, device200includes nanostructure detacher210.

Nanostructure detacher210is to detach nanostructures that are attached to one another. For example, if nanostructures120and121are adhered together due to van der Waals forces, nanostructure detacher210facilitates in detaching nanostructures120and121. It should be appreciated that nanostructure detacher210can be disposed at any location with respect to devices100or200such that it is able to facilitate in detaching nanostructures.

In one example, nanostructure detacher210is a piezoelectric substrate to excite attached nanostructures to a resonant vibration frequency. Once the nanostructures are detached from one another, the resonant frequency is shifted or reduced. Also, the amplitude may be limited, because once the nanostructures are detached, their resonant vibration frequency will be shifted and the nanostructures cannot absorb any more energy from the vibration excitation source.

In another example, nanostructure detacher210is a heat source that thermally expands the attached nanostructures. For example, the thermal expansion of the attached nanostructures can overcome van der Waals forces and result in detaching of the nanostructures.

In a further example, nanostructure detacher210is a magnet (e.g., electro magnet) that provides a magnetic field. For example, a magnetic field provided to the attached nanostructure can facilitate in the attached nanostructures to overcome van der Waals forces and result in detaching of the nanostructures.

At310, a SERS active metal is disposed on a portion of the plurality of nanostructures. For example, gold is disposed on a tip portion of nanostructures120-122.

At320, a low friction film is disposed over the plurality of nanostructures and the SERS active metal, wherein the low friction film is for preventing adhesion between the plurality of nanostructures. For example, low friction film140is uniformly disposed over nanostructures120-122and SERS active metals130-132to prevent adhesion between nanostructures120-122due to van der Waals forces. In various examples, the low friction film can be, but is not limited to, CF4, C2F4, and diamond-like carbon.

At330, attached nanostructures are detached from one another. For example, nanostructures120and121are adhered to one another due to van der Waals forces, as depicted inFIG. 2. However, nanostructure detacher210facilitates in detaching nanostructures120and121. Accordingly, nanostructures120and121are not attached to one another, as depicted inFIG. 1.

In one example, at332, the attached nanostructures are excited to a resonant vibration frequency. For example, a vibration excitation source (e.g., piezoelectric substrate) excites attached nanostructures120and121to a resonant vibration frequency to facilitate in the detaching of nanostructures120and121.

In another example, at334, the attached nanostructures are thermally expanded. For example, a heat source provides heat to attached nanostructures120and121to facilitate in the detaching of nanostructures120and121.

In a further example, at336, a magnetic field is provided to the attached nanostructures. For example, attached nanostructures120and121are provided with a magnetic field to facilitate in the detaching of nanostructures120and121.

Various examples of the present technology are thus described. While the present technology has been described in particular examples, it should be appreciated that the present technology should not be construed as limited by such examples, but rather construed according to the following claims.