Dynamic Deformation Measurement of an Intact Single Cell via Microfluidic Chip with Integrated Liquid Exchange

Integration of Microfluidic Chip and Probe with a Dual Pump System for Measurement of Single Cells Transient Response

“…Furthermore, compared to the reported response time of a large number of Synechocystis cell volume changes [27], the measured response time in this research is reasonable, and we further achieved accurate contact measurements of the force and deformation measurements of a compressed single cell. The average liquid exchange time of the system is over 100 times faster than our previous work and also faster than the response time of cells to osmolarity change [7]. Hence, we successfully exposed the process of a single compressed cell responding to osmolarity change by using a proposed system.…”

“…The liquid exchange occurred from approximately 0.097 s to 0.102 s. The disturbance of the liquid exchange was almost impossible to observe in the displacement data of the sensor probe (Figure 6b). Compared to the disturbance of the liquid exchange in a closed chip using the laminar flow method [7], the probe with the dual pump system achieved localized liquid exchange, which significantly decreases the disturbance under the liquid exchange process and increases the measurement accuracy of the force sensor. To evaluate the disturbance of the sensor probe under liquid exchange accurately, we replaced the cells with PDMS beads that have a similar Young's modulus and size as Synechocystis cells since the volume of PDMS beads is not influenced by osmolarity change.…”

“…Robot-integrated microfluidic chips have immense potential for exploring the biophysical properties of cells. These chips integrate a series of functional components that allow for cell separation, capture, detection, and several other tasks for single cells [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. For instance, an optical tweezers system was used to trap or stretch a single cell [ 2 , 6 , 8 ].…”

“…For instance, an optical tweezers system was used to trap or stretch a single cell [ 2 , 6 , 8 ]. Additionally, on-chip functional probes were fabricated with the chips to puncture or deform the cell, providing insight into the mechanical properties of the cell [ 3 , 4 , 6 , 7 ].…”

Instantaneous extracellular solution exchange for concurrent evaluation of membrane permeability of single cells

“…4 To analyze the single-cell response, the microfluidic chip approach, which has some advantages in terms of observability and environmental controllability, is a powerful tool. 20,21 Despite these advantages, conventional microfluidic chip approaches of solution exchange using streamswitching, 22 which controls streamlines of the initial solution and stimulation solution around cells trapped in a microchannel by alternating their relative flow rates, have been limited to a solution exchange time of 0.3 s. 23 This method has difficulty changing the extracellular environment rapidly because of diffusion of the liquid-liquid interface 24,25 and high hydraulic resistance to switch streamlines. Therefore, it is necessary to establish a novel solutionexchange method for the concurrent evaluation of cellular osmoadaptation at the single-cell level.…”