Regenerative medicine has the capability to revolutionise many aspects of medical care, but for it to make the step from
small scale autologous treatments to larger scale allogeneic approaches, robust and scalable label free cell sorting
technologies are needed as part of a cell therapy bioprocessing pipeline. In this proceedings we describe several
strategies for addressing the requirements for high throughput without labeling via: dimensional scaling, rare species
targeting and sorting from a stable state. These three approaches are demonstrated through a combination of optical and
ultrasonic forces. By combining mostly conservative and non-conservative forces from two different modalities it is
possible to reduce the influence of flow velocity on sorting efficiency, hence increasing robustness and scalability. One
such approach can be termed "optically enhanced acoustophoresis" which combines the ability of acoustics to handle
large volumes of analyte with the high specificity of optical sorting.
We present an optimized optical tweezers system based upon the conical refraction of circularly polarized light in a
biaxial crystal. The described optical arrangement avoids distortions to the Lloyd plane rings that become apparent when
working with circularly polarized light in conventional optical tweezers. We demonstrate that the intensity distribution of
the conically diffracted light permits optical manipulation of high and low refractive index particles simultaneously.
Such trapping is in three dimensions and not limited to the Lloyd plane rings. By removal of a quarter waveplate the
system also permits the study of linearly polarized conical refraction. We show that particle position in the Raman plane
is determined by beam power, and indicates that true optical tweezing is not taking place in this part of the beam.
The increased application of holographic optical manipulation techniques within the life sciences has sparked the
development of accessible interfaces for control of holographic optical tweezers. Of particular interest are those that
employ familiar, commercially available technologies. Here we present the use of a low cost games console interface, the
Microsoft Kinect for the control of holographic optical tweezers and a study into the effect of using such a system upon
the quality of trap generated.
When using single microfluidic droplets as isolated biological/chemical micro-reactors or arrays of droplets as 2D
assaying tools, control over droplet placement is crucial to successful device implementation. Here we demonstrate a
combined mechanical and optical approach to generate highly controllable arrays of droplets in pre-determined 'rails and
anchors' patterns on a two-dimensional plane.
The technique combines passive mechanical forcing with selective laser action. Passive mechanical forcing provides a
vehicle for droplet transport and storage and laser induced optical forcing is employed for stopping, guiding or derailing
droplets as they pass through the chip. In this way intelligent operations can be performed upon arrays of droplets such
as sorting, merging to initiate chemical reactions or selective removal of droplets from a predefined array. The usergenerated
array may then be held static against a mean flow for prolonged observation.