11.6 Summary
Biophotonics technologies are widely used in biomedical research, in the detection
and treatment of diseases and health conditions, and in point-of-care healthcare
clinics. In addition to a broad selection of microscopic and spectroscopic methods
described in previous chapters, this chapter describes other advanced tools and
implementations. These include the following:
- Optical tweezers and optical trapping techniques that enable microscopic
manipulation of cells and molecules for exploring biological materials and
functions in the micrometer and nanometer regime - Miniaturized photonics-based instrumentation functions and devices such as the
lab-on-a-chip and lab-on-fiber technologies - Microscope-in-a-needle concepts to enable 3-dimensional scanning of malignant
tissue within the body - The detection of single nanoscale particles (e.g., viruses) using a method named
interferometric reflectance imaging sensor (IRIS) - Optogenetics procedures, which attempt to explore and understand the mecha-
nisms of neuronal activity in organs such as the brain and the heart.
11.7 Problems.
11 :1 Show that a force of F = 2.5× 103 pN is needed to pick up a grain of maize
pollen that has a mass m = 2.5× 10 −^10 kg.
11 :2 Consider an optical trap that has a stiffness k = 45 pN/μm. If an image
analysis instrument can determine the position of a micrometer-sized sphere
to within 12 nm, show that the force resolution is 0.54 pN.
11 :3 Consider an optical trap that has a trapping efficiency of Q = 0.30. Show that
if a power level of 150 mW is used in the trap and if the refractive index of
the medium is nmed= 1.36, then the total force Ftotalexerted on a particle is
203 pN.
11 :4 Consider an optical trap that has a trapping efficiency of Q = 0.25. Let the
refractive index of the medium be nmed= 1.36. Show that if the total force
Ftotalexerted on a particle is 80 pN, then a power level of 70.8 mW is used in
the trap.
11 :5 Using Web resources (for example, http://www.microfluidic-ChipShop.com),,)
describe the operation of a microfluidic device such as a droplet-generator
chip, a micro-mixer chip, or a particle and cell-sorting chip.
11 :6 The applications of lab-on-a-chip devices routinely require interfaces between
a microfluidic chip and the macroscopic world. Using Web resources (for
example,www.microfluidic-ChipShop.com), describe how an interface chip
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