Inertial and viscous flywheel sensing of nanoparticles

Abstract

Rotational dynamics often challenge physical intuition while enabling unique realizations, from the rotor of a gyroscope that maintains its orientation regardless of the outer gimbals, to a tennis racket that rotates around its handle when tossed face-up in the air. In the context of inertial sensing, which can measure mass with atomic precision, rotational dynamics are normally considered a complication hindering measurement interpretation. Here, we exploit the rotational dynamics of a microfluidic device to develop a modality in inertial sensing. Combining theory with experiments, we show that this modality measures the volume of a rigid particle while normally being insensitive to its density. Paradoxically, particle density only emerges when fluid viscosity becomes dominant over inertia. We explain this paradox via a viscosity-driven, hydrodynamic coupling between the fluid and the particle that activates the rotational inertia of the particle, converting it into a ‘viscous flywheel’. This modality now enables the simultaneous measurement of particle volume and mass in fluid, using a single, high-throughput measurement.

Sensing of Fluidic Features Using Colloidal Microswarms

“…By contrast, the van der Waals attractive energy remains unchanged according to (5). Meanwhile, the electrostatic repulsive energy and van der Waals attractive energy are independent from the fluidic viscosity based on (4).…”

“…With higher fluidic ionic strength, the electric double layers of nanoparticles will be compressed, 36 inducing the decrease of surface potentials s of chains. 39 Meanwhile, the inverse Debye length k will increase with the ionic strength according to (4). Therefore, based on (4), the electrostatic repulsive energy E EDL between the particle chains will be decreased, indicating the chain−chain repulsive interaction in a swarm also will be weaken with high ionic strength.…”

“…Sensing of key parameters (e.g., viscosity and ionic strength) in physiological environments has attracted extensive attention. − The blood viscosity is an important determinant associated with the cardiovascular diseases, − such as stroke and coronary heart disease. The inflammation could also cause alterations of blood viscosity .…”

Nanomechanical Sensing Using Heater-Integrated Fluidic Resonators

“…Micro/nanochannel resonators − are unique physical devices with channels incorporated within their structural bodies, allowing the highly controlled delivery of a variety of fluid samples. Cantilever-type fluidic resonators, with or without an additional dispensing nozzle near their free ends, have been used for gravimetric sensing applications of cells, viruses, suspended micro/nanoparticles, or liquids . They also have applications for dispensing/extracting of drugs, biomolecules, and functional materials , onto target substrates.…”

Weighing the DNA Content of Adeno-Associated Virus Vectors with Zeptogram Precision Using Nanomechanical Resonators

“…The sensitivity, S, for a length scale, L, of the cantilever scales as S ∼ L −5 (Figure 1b, Supporting Information S2) indicating that the smaller the cantilever, the greater the Δf rms . On the basis of the scaling of S and the availability of previously characterized cantilevers, 27 we used the one with the smallest length L = 17.5 μm, a fluid channel with a cross-sectional area 700 × 700 nm 2 , and a baseline resonant frequency f ≅ 4.5 MHz (Supporting Information S4). Next, we measured AAV solutions with distinct genetic constructs, having nominal number n DNA of DNA kilobases (kb), n DNA = 0, 3.3, and 4.9 kb (Supporting Information S5).…”