Method for manufacturing a microfluidic device
A microfluidic device comprises a first substrate ( 102 ) made of a first polymer material and a second substrate ( 104 ) made of a second polymer material, the first ( 102 ) and second ( 104 ) substrates having respective bonding surfaces ( 23, 41 ), at least one of the bonding surfaces ( 41 ) having channel formations ( 14 ) so that, when the bonding surfaces ( 23, 41 ) are bonded by surface deformation to one another, the bonded first and second substrates ( 102, 104 ) and the channel formations ( 14 ) form at least part of a microfluidic channel network comprising a plurality of microfluidic channels, wherein one or more indicator pits ( 11 ), separate to the channel formations ( 14 ) defining the microfluidic channel network, are formed in at least one of the bonding surfaces ( 23, 41 ), so that surface deformation caused by the bonding process causes a change of configuration of the one or more indicator pits ( 11 ).
1. A method of manufacturing a microfluidic device, the method comprising:
providing first and second substrates made of respective first and second polymer materials, the first and second substrates having respective bonding surfaces, at least one of the bonding surfaces having channel formations so that, when the bonding surfaces are bonded by surface deformation to one another, the bonded first and second substrates and the channel formations form at least part of a microfluidic channel network comprising a plurality of microfluidic channels, in which one or more indicator pits, separate to the channel formations defining the microfluidic channel network, are formed in at least one of the bonding surfaces;
providing at least one pair of pits at corresponding positions on the bonding surfaces of each of the first and second substrate so as to provide an alignment indicator;
aligning first and second substrate by bringing the at least one pair of pits of the alignment indicator to overly each other;
softening at least one of the bonding surfaces in preparation for bonding to each other;
and
bonding by compression the bonding surfaces of the first and second substrate, the compression causing a change of configuration of the one or more indicator pits.
2. The method of claim 1 , in which the at least one pair of pits of the alignment indicator are at least one pair of multi-level pits such that at least the shallowest one of the at least one pair of multi-level pits levels of each pit disappearing under the compression.
3. The method of claim 2 , wherein there are at least two levels in each pair of multi-level pits.
4. The method of claim 3 , further comprising: monitoring the number of levels in the at least one pair of multi-level pits of the alignment indicator during bonding; and controlling bonding according to the monitoring.
5. The method of claim 1 , in which one or more groups of adjacent at least one pairs of pits at corresponding positions on the bonding surfaces of each of the first and second substrate are provided so as to provide alignment indicator groups, each at least one pair of pits in the group having a different respective depth.
6. The method of claim 5 , further comprising: monitoring the number of the at least one pair of pits remaining in an alignment indicator group during bonding; and controlling bonding according to the monitoring.
7. The method of claim 1 , wherein said softening and said bonding are selected from the list comprising:
said softening being heating and said bonding is thermal bonding; and
said softening being exposure to a solvent vapour and said bonding being solvent vapour bonding.