Microfluidic manipulation of Caenorhabditis elegans using acoustic radiation forces

The ability to precisely trap, transport and manipulate micrometer-sized objects is very important in microfluidic applications. Caenorhabditis elegans (C. elegans) is one of the most ubiquitous lab animals used for biological research; and for experimental studies and observations it needs to be selected, transported or immobilized. In this study we demonstrate the use of acoustic radiation forces, including Primary Radiation Force (PRF) and Secondary Radiation Force (SRF) to trap and manipulate C. elegans. PRF in a standing wave field is used to trap multiple C. elegans. Simulations are found to be in good agreement with the patterns of the trapped worms. SRF generated around an array of insonated microbubbles is used to trap a single C. elegans and precisely direct its motion in a specified path. Theoretical explanation for SRF to trap and manipuate worms via microbubble arrays is also presented. Viability test proves that the two approaches do not pose harm to the biological matter. Due to non-contact and non-electrical-field nature of the two techniques, we believe that these inexpensive methodologies can pave way for novel lab on a chip technologies for manipulating C. elegans or potentially any other important biological sample.