An on-chip system is presented with integrated architectures for digital microfluidic actuation and sensing. Localized actuation is brought about by a digital microfluidic multiplexer layout that overcomes the challenges of multi-microdrop interference, and complete two-dimensional motion is shown for microdrops on a 14×14 grid with minimized complexity by way of 14+14 inputs. At the same time, microdrop sensing is demonstrated in a folded-cavity design for enhanced optical intensity probing of internal fluid refractive indices. The heightened intensities from this on-chip refractometer are shown to have a linear response to the underlying fluid refractive index. An electro-dispensing technique is used to fabricate the folded-cavity optical architecture in a format that is tuned for the desired refractive index range and sensitivity. The overall lab-on-a-chip system is successful in integrating localized microdrop actuation and sensing.
A digital microfluidic architecture is introduced for micron-scale localized fluid actuation and in in-situ optical sensing.
Contemporary device integration challenges related to localization and device scalability are overcome through the
introduction of a bi-layered digital microfluidic multiplexer. Trinary inputs are applied through differential combinations
of voltage signals between upper (column) electrodes and lower (row) electrodes. The ultimate layout provides increased
scalability for massively parallel microfluidic actuation applications with a minimal number of inputs. The on-chip
sensing technique employed here incorporates a microlens in a folded-cavity arrangement (fabricated by a new voltage-tuned
polymer electro-dispensing technique). Such a geometry heightens the sensitivity between the optical probe and
fluid refractive properties and allows the device to probe the refractive index of the internal fluid. This optical
refractometry sensing technique is merged with the actuation capabilities of the digital microfluidic multiplexer on a
single lab-on-a-chip device.