Biology subjects

Sachs, D. M.

Publications and source records attributed to Sachs, D. M..

2 recordsLinked to original sources

bioRxiv2023

Robotic System for Organoid Assembly in a Multi-Well Microfluidic Chip

While many cell culture systems are sensitive to the conditions in which cells are introduced into the system, we find that in situ differentiated tube-shaped microfluidic organoids have a particularly high sensitivity. Preliminary experiments using conventional seeding techniques revealed that biases in initial cell number and distribution dramatically impacted organoid shape and behavior downstream. Residual flows during seeding further complicated the process, dispersing cells to undesirable locations within the chip. To address this problem, a a robotic seeding system for controlling the process of inserting cells into microfluidic chips was developed. Environmental control of temperature, CO2, and humidity was implemented by modifying a commercial Arduino-controlled incubator. An eight-channel syringe pump controlled flow to eight cell dispensers, while a vertical leadscrew stage raised and lowered them, and a set of stackable flexure micromanipulators individually controlled the X and Y position of each cell dispenser. The flexure manipulators were 3D printed, driven by low-cost motors and electronics, and required little assembly and no alignment, resulting in a cheap and scalable method of controlling a dense array of micromanipulators. A dual objective microscope on a motorized gantry used an oblique lighting system to observe the seeding process, allowing for real-time interventions or passive observation of automated protocols. The robotic cell seeding system provided a platform for optimizing a sensitive process towards increasing the repeatability and physiological relevance of tube-shaped microfluidic organoids.

bioengineering↗

bioRxiv2023

Automated Stimulation and Long-Term Remote Monitoring of Multi-Plex Microfluidic Organoid Chips

Developing a novel microfluidic organoid system required many experiments and iterations due to lack of knowledge about the relevant developmental biology. Collecting data on the developing organoids quickly escalated into a bottleneck as high throughput and long term culture resulted in a rapidly increasing number of specimens being observed. Commercially available automated microscope systems exist, but were either too expensive or not appropriate, and could not be modified. To satisfy the increasing need for automated data collection, a custom robotic system was developed to collect data from within a standard incubator. An X-Y belt driven gantry was designed with an architecture chosen to balance high accuracy, low cost, speed, and range of motion. Focus control was implemented with dual miniature leadscrews. A linear sliding mechanism was used to switch between two microscope objectives. 3D printed chip attachments were designed to implement illuminators for bright field imaging, and electrodes for stimulating the cardiac organoids. A fluorescent filter block was designed using a 3D printed piece to hold optical components, and a multi-band filter set that allowed for three color fluorescence without moving parts. A pulley driven tilting stage gravitationally biased the organoids during development. In order to ensure accurate image collection despite the inevitable position shifting of the chips, an image processing pipeline was developed for locating organoids using geometrical microfluidic chip features. The resulting robotic system automated imaging data collection on organoids and electrical and mechanical stimulation, in addition to being modifiable for future projects.

bioengineering↗