Recently, ATR-IR has been applied to microfluidic flows of aqueous solutions by engineering microreactors with built-in apertures for the ATR crystal, allowing the flow within microchannels to pass across the crystal surface for characterisation,[3] or in dedicated flow cells.[4][5] The ability to passively characterise samples, with no sample preparation has also led to the use of ATR-FTIR in studying trace evidence in forensic science.