A test card comprising: a body comprising a first surface and a second surface opposite the first surface; at least one well defining an opening extending from the first surface to the second surface and configured to receive a sample therein; wherein the at least one well comprises a wall bounding the opening and extending between the first surface and the second surface of the card; wherein a supply conduit connects to the at least one well at the wall; wherein sealing membranes are disposed on both the first surface and the second surface covering the opening of the at least one well at both the first surface and the second surface; characterized in that: the at least one well further comprises a shelf defining a shelf surface, wherein a first portion of the wall extends from the shelf surface to the first surface and a second portion of the wall extends from the shelf surface to the second surface, and wherein the shelf protrudes from the wall at a junction of the first portion and the second portion, wherein the opening is narrower between the shelf and the second surface than between the shelf and the first surface, wherein the shelf surface is substantially parallel to the first surface or the second surface, and the supply conduit connects to the at least one well at the wall at a location between the shelf and the first surface such that the shelf is formed at a portion of the wall beneath the connection of the supply conduit. a body comprising a first surface and a second surface opposite the first surface; at least one well defining an opening extending from the first surface to the second surface and configured to receive a sample therein; wherein the at least one well comprises a wall bounding the opening and extending between the first surface and the second surface of the card; wherein a supply conduit connects to the at least one well at the wall; wherein sealing membranes are disposed on both the first surface and the second surface covering the opening of the at least one well at both the first surface and the second surface; characterized in that: the at least one well further comprises a shelf defining a shelf surface, wherein a first portion of the wall extends from the shelf surface to the first surface and a second portion of the wall extends from the shelf surface to the second surface, and wherein the shelf protrudes from the wall at a junction of the first portion and the second portion, wherein the opening is narrower between the shelf and the second surface than between the shelf and the first surface, wherein the shelf surface is substantially parallel to the first surface or the second surface, and the supply conduit connects to the at least one well at the wall at a location between the shelf and the first surface such that the shelf is formed at a portion of the wall beneath the connection of the supply conduit. the at least one well further comprises a shelf defining a shelf surface, wherein a first portion of the wall extends from the shelf surface to the first surface and a second portion of the wall extends from the shelf surface to the second surface, and wherein the shelf protrudes from the wall at a junction of the first portion and the second portion, wherein the opening is narrower between the shelf and the second surface than between the shelf and the first surface, wherein the shelf surface is substantially parallel to the first surface or the second surface, and the supply conduit connects to the at least one well at the wall at a location between the shelf and the first surface such that the shelf is formed at a portion of the wall beneath the connection of the supply conduit.