Measurement of body volume of live C. elegans by microchip

We propose a microfluidic device to analyze the feature of Caenorhabditis elegans (C. elegans) from an electric property. In this device, we assessed the body volume of C. elegans using the microchip which has a capacitance sensor. This device is mainly composed of two parts. One is a tapered micro channel. The tapered micro channel was used to immobilize C. elegans. The other is a pair of electrode. The electrode is used to measure the capacitance change. These two components make a sensing space and the capacitance change happens when C. elegans is placed in the sensing space. To measure the body volume of C. elegans by the capacitance change, the suspension with C. elegans was introduced from the inlet and then the solution was sucked through the tapered micro channel by negative pressure. The body volume and the capacitance change of total 15 C. elegans were measured. To get the body volume, first, the body length and the body width of C. elegans were measured by the digital optical microscope and the volume was calculated from two measured values. The capacitance change was measured by the proposed microchip. By comparison with the result of two methods, we confirmed the capacitance change was related with the body volume of C. elegans.