Capillary well microplate

Abstract

Microplates with deep hydrophobic coated wells are standard tools in analytical research and clinical diagnostic screening. High throughput screening demands the dispensation of small volumes of liquid; which, in turn, exacts precise positioning in instrumentation. This precision condition can be significantly relaxed in the approach described here where droplets are released at the entrance of the well and fill it by capillary forces alone; provided that a critical diameter to volume condition dependent on the liquid-solid hydophibicity is fulfilled. After filling, the liquid column typically remains stationary even if the bottom end of the well is open.

Sliding variability of droplets on a hydrophobic incline due to surface entrained air bubbles

“…The use of droplets in isolation logically overcomes these limitations and is, not surprisingly, finding increasing use in assay applications [4]. It also plays a role in the ability of droplets to fill capillaries, for instance, is vital in new schemes of microplate instrumentation [5], and particle harvesting [6].…”

Capillary Wells Microplate with Side Optical Access

“…This demonstrates the ability of the design to account for pipetting errors during the actual assay run itself. If we suppose that the length information can be ascertained to an accuracy of 10 µm, the use of a capillary well with internal diameter 0.2 mm should result in the ability to detect pipetting errors of 0.31 picoliters based on equation (2). Obviously, the use of a smaller internal diameter enhances the volume error sensitivity.…”

“…Differentiating and rearranging gives . Equation (2) indicates that for small values of D, any volumetric error results in large variation in the registered liquid length. Hence, the use of capillary wells, in which the internal diameter is generally small, permits sensitive detection of volumetric error from pipetting.…”

“…We have reported the idea of having the microplate wells themselves functioning like capillaries. 2 With this method, droplets can be released at the entrance of the well and will fill into it by capillary force alone if the well surface is hydrophilic. After filling, the liquid column typically remains stationary even if the bottom end of the well is open.…”

“…20 Liquid samples are delivered via an automated or manual pipette in the form of droplets, which is drawn into the wells using the capillary effect as detailed previously. 2 The volume V that fills each well is related to the length L and internal diameter D via . Differentiating and rearranging gives .…”