Bonding Of Lab-on-a-Foil Via A PDMS Substrate Holder

In recent years,researchers have proposed that microchannel networks were fabricated on a polymer film,and then after a bonding with a cover plate,a lab-on-a-foil is formed.The lab-on-a-foil has several merits,such as low material consumption,low cost and efficient thermal response.However,collapse of three-dimensional microchannel on a film substrate easily happen during the bonding.Hence,this work proposed the PDMS substrate holder was directly cast from the structured polymer film.It can protect the three-dimensional microchannel on a film substrate from deformation.First of all,the PDMS substrate holder was fabricated by cast molding and was used for the bonding of lab-on-a-foil.Fabrication process of the PDMS substrate holder was optimized.On the one hand,the PDMS substrate holder was cured at room temperature for 48 h and the contraction deformation after demoulding could be avoided.On the other hand,the PDMS substrate holder cured by mixing the prepolymer and curing agent in 10:1 had a lower modulus and was good for evenly distribution of the bonding pressure.It has also several advantages,such as good alignment,simple production process,low cost,easy location,evenly distribution of the pressure and good durability.Second,the bonding quality of the lab-on-a-foil was characterized by centrifuging the red food dye into the lab-on-a-foil,using SEM to observe the morphology of microstructure and using the air compressor to test the bonding strength.384 reaction chambers were filled with red food dye,which indicates no clogging for connecting channel and no leakage around the connecting channel and reaction chamber.All microstructures were well sealing by using SEM.The pressure test showed the average bond failure pressure was 0.39+0.03 MPa.Finally,the performance of the lab-on-a-foil was characterized by RQ-qPCR.The average C_T value of the 64 reactions selected randomly was 18.060 with a low standard deviation of0.306,which is similar to the test results of congeneric chips in the market.This experiment demonstrates that the lab-on-a-foil device bonded with the help of the PDMS holder is compatible with PCR reactions.