Microfluidic device comprising: - a microfluidic card which comprises: ∘ a first microfluidic structure comprising first microfluidic connection points intended to be passed through by a fluid, ∘ a first bearing surface, ∘ first means for assembling and centring a microfluidic component on said bearing surface, - a microfluidic component which comprises: ∘ a second microfluidic structure comprising second microfluidic connection points intended to be passed through by a fluid and microfluidic channels linking its second microfluidic connection points so as to form a network of interconnected microfluidic elements, and intended to be connected to the first microfluidic structure of the microfluidic card to connect said first microfluidic connection points with said second microfluidic connection points, ∘ second assembly and centring means arranged to cooperate with said first assembly and centring means of the microfluidic card, - a seal capable of ensuring a tight connection between the first microfluidic structure and the second microfluidic structure, characterized in that: - said first assembly and centring means comprise at least one first assembly element based on magnetic effect fixed to said microfluidic card and arranged to cooperate by magnetic effect with a second assembly element based on magnetic effect of said microfluidic component to compress said seal capable of ensuring a tight connection between the first microfluidic structure and the second microfluidic structure, - said first assembly and centring means comprise at least one first mechanical member intended to cooperate with a second mechanical member of said second assembly and centring means of said microfluidic component, - said first mechanical member comprises at least one cavity produced in the card, - said second mechanical member comprises at least one block intended to cooperate by male/female operation with said cavity produced on the microfluidic card, - said first assembly element based on magnetic effect is housed at the bottom of said cavity, - said second assembly element based on magnetic effect is housed in said block. - a microfluidic card which comprises: ∘ a first microfluidic structure comprising first microfluidic connection points intended to be passed through by a fluid, ∘ a first bearing surface, ∘ first means for assembling and centring a microfluidic component on said bearing surface, ∘ a first microfluidic structure comprising first microfluidic connection points intended to be passed through by a fluid, ∘ a first bearing surface, ∘ first means for assembling and centring a microfluidic component on said bearing surface, - a microfluidic component which comprises: ∘ a second microfluidic structure comprising second microfluidic connection points intended to be passed through by a fluid and microfluidic channels linking its second microfluidic connection points so as to form a network of interconnected microfluidic elements, and intended to be connected to the first microfluidic structure of the microfluidic card to connect said first microfluidic connection points with said second microfluidic connection points, ∘ second assembly and centring means arranged to cooperate with said first assembly and centring means of the microfluidic card, ∘ a second microfluidic structure comprising second microfluidic connection points intended to be passed through by a fluid and microfluidic channels linking its second microfluidic connection points so as to form a network of interconnected microfluidic elements, and intended to be connected to the first microfluidic structure of the microfluidic card to connect said first microfluidic connection points with said second microfluidic connection points, ∘ second assembly and centring means arranged to cooperate with said first assembly and centring means of the microfluidic card, - a seal capable of ensuring a tight connection between the first microfluidic structure and the second microfluidic structure, characterized in that: - said first assembly and centring means comprise at least one first assembly element based on magnetic effect fixed to said microfluidic card and arranged to cooperate by magnetic effect with a second assembly element based on magnetic effect of said microfluidic component to compress said seal capable of ensuring a tight connection between the first microfluidic structure and the second microfluidic structure, - said first assembly and centring means comprise at least one first mechanical member intended to cooperate with a second mechanical member of said second assembly and centring means of said microfluidic component, - said first mechanical member comprises at least one cavity produced in the card, - said second mechanical member comprises at least one block intended to cooperate by male/female operation with said cavity produced on the microfluidic card, - said first assembly element based on magnetic effect is housed at the bottom of said cavity, - said second assembly element based on magnetic effect is housed in said block.