A pumpless cell culture chip with the constant medium perfusion-rate maintained by balanced droplet dispensing

This paper presents a pumpless cell culture chip, where a constant-rate medium perfusion is achieved by balanced droplet dispensing. Previous pumpless cell culture chips, where the gravity-driven flow is induced by gradually decreasing the hydraulic-head difference, Δh, between source and drain reservoirs, result in a decreasing perfusion-rate. However, the present pumpless cell culture chip, where autonomous droplet dispensers are integrated on the source reservoirs, results in a constant perfusion-rate using a constant Δh maintained by balanced droplet dispensing between the source-inlet and the drain-outlet. In the experimental study, constant perfusion-rates of 0.1, 0.2, and 0.3 μl min⁻¹ are obtained by Δh of 38, 76, and 114 mm, respectively. At the constant perfusion-rate (Q = 0.2 μl min⁻¹), H358 lung cancer cells show the maximum growth-rate of 57.8 ± 21.1% d⁻¹, which is 1.9 times higher than the 30.2 ± 10.3% d⁻¹ of the static culture. At a perfusion-rate varying between 0.1–0.3 μl min⁻¹ (average = 0.2 μl min⁻¹), however, the H358 cells show a growth-rate of 46.9 ± 8.3% d⁻¹, which is lower than that of the constant Q of 0.2 μl min⁻¹. The constant-rate perfusion culture (Q = 0.1, 0.2, and 0.3 μl min⁻¹) also results in an average cell viability of 89.2%, which is higher than 75.9% of the static culture. This pumpless cell culture chip offers a favorable environment to cells with a high growth-rate and viability, thus having potential for use in cell-based bio-assays.