Detection of sub-degree angular fluctuations of the local cell membrane slope using optical tweezers

Abstract

We ascertain pitch angle of a spherical birefringent particle using optical tweezers and use it to find cell membrane parameters.

Estimation of rolling work of adhesion at the nanoscale with soft probing using optical tweezers

“…We rst calibrate the pitch motion of the birefringent particle by trapping it away from the surfaces and ascertaining the power spectral density of the thermal motion of the pitch mode of rotation. 20,27 This has been shown in Fig. 3 and has been tted to a Lorentzian.…”

“…The pitch motion is inferred from the difference in signals from the two photodiodes. 20 Current preampliers PDA200C (Thorlabs) were placed on the outputs for the two photodiodes with a bandwidth of 20 KHz. A National Instruments data card NI-DAQ 6212 BNC with a data acquisition rate of 10 kilo samples per second has been used to acquire data for the time series.…”

“…In the experiment the PSD is measured in V 2 Hz À1 units as shown in Fig. 3 which has to be calibrated and converted to rad 2 Hz À1 using a calibration factor (b) [20][21][22] given as Fig. 1 This cartoon shows how a spherical particle confined at the center by an optical trap, rolls on a surface which has been moved parallel to the surface.…”

A hydro-thermophoretic trap for microparticles near a gold-coated substrate

“…The particle is spatially confined in all three dimensions but also observed to be executing different out-of-plane rotations, namely roll 34 and pitch [40][41][42][43] due to the thermoplasmonic fluid flow. It is not exactly clear why the particle executes this rotation but it could arise from minor differences in fluid velocities in the local neighborhood of the equilibrium location.…”

Simultaneous optical trapping and magnetic micromanipulation of ferromagnetic iron-doped upconversion microparticles in six degrees of freedom

“…The upconverting NaYF 4 :Yb,Er (NYF) non-magnetic particles have been routinely used with optical tweezers [26][27][28] but, for the first time, the magnetic properties of these NYF through co-doping with Fe are being explored. We show that this co-doped particle can be held in optical tweezers while the magnetic field could be used to turn the particle in all the three degrees of freedom, namely, yaw [29][30][31][32] , pitch 27,[33][34][35] and roll, in the nomenclature of the airlines.…”