Laser doppler electrophoresis using a diffusion barrier

An electrophoretic instrument, comprising:

• a generally upright, u-shaped vessel, including:
• a transparent bend,
• a first upright leg connected to a first side of the bend and extending upward from the bend,
• a second upright leg connected to a second side of the bend and extending upward from the bend,
• a first electrode volume connected to an upward end of the first upright leg opposite the bend and extending horizontally away from the first upright leg, and
• a second electrode volume connected to an upward end of the second upright leg opposite the bend and extending horizontally away from the second upright leg,
• a first electrode disposed in the first electrode volume and horizontally offset from the first upright leg,
• a second electrode disposed in the second electrode volume and horizontally offset from the second upright leg, and
• a cell body for supporting the bend, the first upright leg, the second upright leg, the first electrode volume, the second electrode volume, and the first and second electrodes.

An electrophoretic instrument, comprising:

• a generally upright, u-shaped vessel, including:
• a transparent bend,
• a first upright leg connected to a first side of the bend and extending upward from the bend,
• a second upright leg connected to a second side of the bend and extending upward from the bend,
• a first electrode at an upward end of the first upright leg opposite the bend,
• a second electrode at an upward end of the second upright leg opposite the bend,
• wherein the first upright leg defines a sufficient diffusion barrier volume to prevent dispersion of a sample located in the bend to the first electrode before a frequency shift in light that has interacted with the sample can be detected while an alternating electric field is applied to the sample across the first and second electrodes,
• wherein the second upright leg defines a sufficient diffusion barrier volume to prevent dispersion of the sample located in the bend to the second electrode before the frequency shift in light that has interacted with the sample can be detected while the alternating electric field is applied to the sample across the first and second electrodes, and
• a rectangular transparent housing that includes the u-shaped vessel, wherein the transparent housing is constructed and adapted to be held in a cuvette holder for the instrument.

An electrophoretic instrument, comprising:

• a vessel,
• a first electrode,
• a second electrode,
• a first diffusion barrier between a sample location and the first electrode, wherein the first diffusion barrier includes a volume of dispersant,
• a second diffusion barrier between the sample location and the second electrode, wherein the second diffusion barrier includes a volume of dispersant,
• a temporally coherent illumination source positioned to illuminate the sample location, and
• a frequency-shift detector positioned to receive illumination from the sample location after interaction with the sample.