Microfluidic trapping chip and uses thereof for culture and assay of cell clusters and objects

A microfluidic chip for trapping a plurality of objects, the microfluidic chip comprising:

• a body including:
• one or more upstream inlets;
• one or more downstream outlets;
• a first plurality of trapping channels having a collective flow resistance and comprising three or more parallel trapping channels, wherein each trapping channel of the first plurality of trapping channels is fluidically connected to the one or more upstream inlets and to the one or more downstream outlets and has a trapping channel length and comprises one single hydrodynamic trap and no other hydrodynamic traps, the single hydrodynamic trap defined by a structural constriction in a respective trapping channel configured to:
• trap an object having a diameter in a range of 10 microns to 1 mm, and
• direct all of a fluid flowing into the respective trapping channel into the single hydrodynamic trap of the respective trapping channel,
• wherein for each trapping channel in the first plurality of trapping channels, the one or more upstream inlets and the respective trapping channel up to the single hydrodynamic trap defines:
• a flow path distance from the one or more inlets to the respective single hydrodynamic trap wherein the flow path distance of each trapping channel of the first plurality of trapping channels is identical across the first plurality of trapping channels, and
• a channel volume from the one or more upstream inlets to the respective single hydrodynamic trap, wherein the channel volume of each trapping channel of the first plurality of trapping channels is identical across the first plurality of trapping channels;
• a main channel upstream of the first plurality of trapping channels, the main channel fluidically connected to the first plurality of trapping channels;
• and
• a bypass channel having a bypass channel length, a bypass channel flow resistance, a bypass channel upstream end, and a bypass channel downstream end, the bypass channel parallel to the first plurality of trapping channels,
• wherein the bypass channel branches from the main channel upstream of the fluidic connection to the first plurality of trapping channels, bypasses the first plurality of trapping channels, and does not include any hydrodynamic traps;
• wherein the bypass channel upstream end is fluidically connected to the one or more upstream inlets and the bypass channel downstream end is fluidically connected to the one or more downstream outlets;
• wherein the bypass channel length is longer than each trapping channel length and the bypass channel flow resistance is higher than the first plurality of trapping channels collective flow resistance when two or more single hydrodynamic traps of the first plurality of trapping channels contain no trapped object;
• and
• wherein the bypass channel flow resistance is lower than the first plurality of trapping channels collective flow resistance when the single hydrodynamic trap of each respective trapping channel in the first plurality of trapping channels includes a trapped object.