A micropillar-based on-chip system for continuous force measurement ofC. elegans

Abstract

Caenorhabditis elegans is a well-established model organism and has been gaining interest particularly related to worm locomotion and the investigation of the relationship between muscle arms and the motion pattern of the nematode. In this paper, we report on a micropillar-based on-chip system which is capable of quantifying multi-point locomotive forces of a moving C. elegans. A Polydimethylsiloxane (PDMS) device was microfabricated to allow C. elegans to move in a matrix of micropillars in a channel, and an image processing method was developed to resolve the worm force from the bending pillars. The current micropillar-based system is able to measure force with a resolution of 2.07 μN for body width of 80 μm. Initial experiments have been conducted to collect a maximum force level for thirteen wild type worm samples. A maximum force level of 61.94 μN was observed from 1571 data points, based on which an average maximum force level was 32.61 μN for multi-point measurements. The demonstrated capabilities of the system can be an enabling technology that allows biologist to gain a better understanding of subtle force patterns of C. elegans and worm muscle development.

On-chip analysis of C. elegans muscular forces and locomotion patterns in microstructured environments

“…37 Since the pillar height is not equal to the chamber depth, a two-layer photoresist mould was used. SU-8 photoresist was spin-coated onto a silicon wafer to first create a base of 20 mm thick SU-8 2025.…”

An integrated platform enabling optogenetic illumination of Caenorhabditis elegans neurons and muscular force measurement in microstructured environments

“…It shows rather significant variations compared to the reported data earlier, 13 which measured the force at 5 Hz. According to our force measurement method, 13,34 the significant variations between the data points in each curve are not mainly attributed to measurement noises. We believe these are the real signal variations.…”

“…(iv) Finally, how to obtain its locomotion metrics? This question is then answered by the post-processing module previously reported, 34 which analyzes time-stamped image sequences obtained in (i).…”

“…29 Furthermore, when made of materials, such as PDMS or SU-8, the pillars were capable of measuring subtle micro-Newton-scale mechanosensation forces between the worm body muscles and the pillars. [32][33][34] Enabled by the force measurement techniques, the locomotion patterns could be precisely described quantitatively and correlated to environmental variables, which are favored by biologists. Meanwhile, it is still desirable to advance this further by incorporating means of manipulating neurons and thus provide a platform that allows mapping of external stimuli, internal neuron circuits, and locomotion patterns.…”

Stress-strain relationship of PDMS micropillar for force measurement application

“…When the aspect ratio (i.e. height-to-diameter ratio) of a cantilever beam is greater than 5, deflection due to the shear can be safely ignored as it contributes less than 5% to the total deflection [11]. However, as the aspect ratio of the micropillar is smaller than 5, hence both bending and shear must be considered in the force-deflection mechanics model.…”