Patented Biochip Technology (“lab-on-chip”)

Amphasys redefines impedance-based cell analysis through a chip-based high frequency approach. This new method provides a label-free solution for microfluidic single cell analysis.

The heart of the cytometer consists of a microfluidic chip supplied with microelectrodes. In this chip we measure changes of the electrical impedance (resistance) of a fluidic medium when cells or other particles pass through the applied electric field. The high sensitivity of the device is achieved by adjusting the channel dimensions close to the size of the measured cell type, increasing thereby the ratio between cell and detection volume. Thus, for the various cell types chips with different channel dimensions are available for optimal sensitivity.

Impedance Flow Cytometry – Reinvented by Amphasys

The origins of impedance-based cell analysis reach back to the 1950's, when Wallace Coulter developed a device in which cells, normally surrounded by an insulating lipid membrane, changed the resistance of an electric field applied across a small orifice when they passed through it. The applied current was DC or low frequency AC and enabled cell counting and volume determination. Coulter counters were mainly used in clinical laboratories for blood cell counting.

Amphasys enhances and miniaturizes the Coulter principle with a chip-based approach by applying AC in the radio frequency range (from 100 kHz to 30 MHz) and minimizing the detection volume (“lab-on-a-chip”). This allows a more accurate cell analysis and provides higher information content that simply outclasses the analyses of conventional Coulter counters. The chip has been developed and patented in collaboration with the Swiss Federal Institute of Technology Lausanne (EPFL).

The main difference from the Coulter principle is that we are measuring with AC (alternating current) over a broad frequency range, while Coulter works with DC (direct current) or with AC at very low frequencies. However, at higher frequencies the cell becomes more and more „transparent“ for the electric field thereby changing the electrical properties of the detected signal. Amphasys measures the impedance of passing cells at up to 4 frequencies at the same time which allows the recognition of a range of cell characteristics like size, viability and cytoplasmic features.

For more details see our brochure about impedance flow cytometry.