A device for generating microbubbles in a gas and liquid mixture and injection device, the device comprising: a housing defining a mixing chamber; means for mixing solution contained in the mixing chamber to generate microbubbles in the solution; a needle array removably attached to the housing and in fluid connection with the mixing chamber, the needle array including at least one needle; and at least one pressure sensor for measuring tissue apposition pressure, the pressure sensor being mounted on one of the housing and the needle array.