# US 2014/0150534 A1 · Scanning non-contact surface microrheometer

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- Number: US 2014/0150534 A1
- Document ID: US20140150534A1
- Status: Published application
- Kind: A1
- Application number: 14/065,755
- Filed: 2013-10-29
- Published: 2014-06-05
- Earliest claimed: 2012-10-29
- Assignees: The Regents of the University of California
- Applicants: The Regents of the University of California
- Inventors: Michael Dennin; Thomas Boatwright; Alexander Levine; Arthur A. Evans; Roy Shlomovitz
- Web page: https://patentgrep.com/patent/US20140150534A1

## CPC

- G01N 11/00: Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties
- G01N 13/00: Investigating surface or boundary effects, e.g. wetting power; Investigating diffusion effects; Analysing materials by determining surface, boundary, or diffusion effects (scanning-probe techniques or apparatus G01Q)
- G01N 2203/005: Electromagnetic means
- G01N 2203/0089: Biorheological properties
- G01N 2203/0286: Miniature specimen; Testing on microregions of a specimen
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

The disclosure provides non-contact microrheological methods that can measure the fluctuation of a particle in a monolayer, where the particle is hydrodynamically coupled to the monolayer. The disclosure further comprises devices to carry out the non-contact microrheological methods thereof, including Laser Tweezer devices which can study in vitro biological processes.

## Claims

### Claim 1

A non-contact microrheological method comprising: measuring a particle fluctuation of a particle in or near a monolayer by using a weak laser trap in combination with a back focal plane displacement detection scheme, wherein the particle is held at a fixed depth below an air/liquid, liquid/liquid, or solid/liquid interface and its small fluctuations in a plane parallel to the monolayer surface is measured, and wherein the particle is hydrodynamically coupled to the monolayer.

### Claim 2 (depends on 1)

The non-contact microrheological method of claim 1, wherein a quadrant photodiode detection system is used to measure the particle's position.

### Claim 3 (depends on 1)

The non-contact microrheological method of claim 1, further comprising extracting from the particle fluctuation measurements an in-plane response function.

### Claim 4 (depends on 3)

The non-contact microrheological method of claim 3, further comprising determining the in-plane response function in terms of the hydrodynamic modes of the system and their associated moduli.

### Claim 5 (depends on 3)

The non-contact microrheological method of claim 3, wherein the in-plane response function takes into account the role of a subphase, the contact angle between the particle and the interface, and changes in the monolayer itself induced by the particles.

### Claim 6 (depends on 1)

The non-contact microrheological method of claim 1, comprising correcting the particle fluctuation measurements for one or more optical effects.

### Claim 7 (depends on 6)

The non-contact microrheological method of claim 6, wherein the optical effects arise from either: (1) changes in the background intensity of reflected light as the depth is changed, (2) particle lensing effects acting on reflected light, or (3) a combination thereof.

### Claim 8 (depends on 1)

The non-contact microrheological method of claim 1, wherein the method utilizes one or more of Equations 1-20.

### Claim 9 (depends on 1)

A device for carrying out the non-contact microrheological method of claim 1.

### Claim 10 (depends on 9)

The device of claim 9, comprising a monolayer trough coupled with a liquid immersion objective; an optical trap using a laser; an optical system comprising a beam expander, steering lenses, mirrors, which focuses the beam to form the optical trap, wherein the trough is attached to a vertical translation stage so that the fixed objective can trap particles at various distances below the surface.

### Claim 11 (depends on 10)

The device of claim 10, wherein the trapped particles scatter laser light back through the objective, onto both a quadrant photodiode (“QPD”) and an intensified CCD camera, wherein the quadrant photodiode allows high frequency 2-dimensional position measurements to be recorded via a data acquisition board and analysis software.

### Claim 12 (depends on 9)

The device of claim 9, further comprising a laser tweezer that can measure bulk mechanical properties of biological systems.

### Claim 13 (depends on 12)

The device of claim 12, wherein the device uses a response function that is measured directly by comparing an applied force and the particles displacement using an oscillatory measurement (“AMR”).

### Claim 14 (depends on 12)

The device of claim 12, wherein the device manipulates a particle by using an oscillating Ytterbium fiber-laser trapping beam, wherein the particle acts as a lens to steer the diode laser detection beam as detected by the QPD; and wherein the particles elastic and viscous interactions with a surrounding liquid medium can be measured.