The invention itself, as well as a preferred mode of use, further objects, and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein:
Referring now to the drawings and in particular to
mλ=p(sin α+sinθ) (1)
where m is the diffraction order, λ is the wavelength of light, p is the pitch of gratings 10, α is the angle of illumination, and θ is the diffraction angle.
If pitch p of grating 10 is changed by Δp via compressing grating 10, the change in diffraction angle θ for normal illumination, Δθ, can be calculated by
where m is the diffraction order, λ is the wavelength of light, p is the pitch of gratings 10, α is the angle of illumination, and θ is the diffraction angle.
The working principles of an optical-encoded force sensor is governed by equation (2). Equation (2) shows that the sensitivity of an optical-encoded force sensor can be increased by reducing pitch p of grating 10 in order to match the wavelength of light at the nanometer regime.
With reference now to
Optical-encoded force sensor 20 is also equipped with electrostatic comb drive actuators 29 that are capable of moving cantilever probe 22 and compress reflective phase grating 26 by application of a voltage between a bank of stator combs 24 and a bank of movable comb 25. Electrostatic comb drive actuators 29 can be used to mechanically bias reflective phase grating 26 to tune its force measurement range and sensitivity to the requirements of a specific application, and for microsurgical operations to penetrate a cell and deliver genetic material using a probe equipped with a microfluidic channel, for RNA interference (RNAi) studies.
Referring now to
As has been described, the present invention provides a mechanically-tunable optical-encoded force sensor.
While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.
The present application claims priority under 35 U.S.C. § 119(e)(1) to provisional application No. 60/828,684 filed on Oct. 9, 2006, the contents of which are incorporated herein by reference.
Number | Date | Country | |
---|---|---|---|
60828684 | Oct 2006 | US |