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Silicon Biosystems patented technology
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Silicon Biosystems’ core technology is based on the ability of an electric field to exert forces on neutral but polarisable particles, such as cells, suspended in a liquid. According to this particular electrokinetic principle, which is called dielectrophoresis (DEP), a neutral particle, when subject to non-uniform electric fields, experiences a net force directed towards locations with increasing (positive dielectrophoresis -pDEP) or decreasing (negative dielectrophoresis -nDEP) field intensities. More specifically, a particle can be subject to pDEP or nDEP according to the (frequency-dependent) electrical properties of the particle and its suspending medium, the particle dimension and the gradient of the electric field. In our approach, the electric field is generated by a silicon chip directly interfaced to a microchamber containing living or non-living particles in liquid suspension. The microchamber is confined between the chip surface and a conductive transparent lid spaced tens of microns apart. The chip surface implements a two dimensional array of microlocations, each consisting of a surface electrode, embedded sensors and logic. The electrodes induce suitable closed nDEP cages in the spatial region above selected microsites, within which single particles may be trapped and levitated individually. Step by step, DEP potential cages can be moved around the device plane concurrently and independently, thus grabbing and dragging single cells and/or microbeads to or from any microchamber location. Separation of heterogeneous populations can be performed by either exploiting DEP spectrum characterisation (i.e. using the frequency-dependent DEP force changing from positive to negative or vice versa) or by using labelling techniques based on functionalised microbeads or fluorescent dyes. Silicon Biosystems’ patented approach represents an enabling technology platform that offers possibilities not achievable with traditional laboratory instrumentation or with other LOACs. |
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Sketch of the proposed LOAC. Cells are individually trapped in dielectrophoretic cages and are manipulated by reconfigurable electric fields generated by programmable electrodes embedded in the chip. |
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Features
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More specifically, the unprecedented features can be summarised as follows:
- Massively parallel individual cell/microbead operation. Hundreds of thousands of single particles can be trapped and moved individually within the microchamber. This grab-and-drag approach is essential for manipulating rare cell populations or small cell loads.
- Embedded sensors. The on-chip sensors allow one to detect the results of experiments, thus enabling fabrication of portable, stand-alone, low-cost devices.
- Programmability. Since both sensing and actuation can be performed on silicon, complex protocols can be managed at a microscopic scale under software control.
- Contactless movement. Cells are levitated and moved without friction or collision against chamber walls. This helps to overcome problems such as cell adhesion, which is quite common when using microfluidic approaches. While traditional TECHNOLOGYs are geared to work either on whole populations or on a single cell, we can control each individual cell on the chip.
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