In IPR2015-01157, 10X Genomics, Inc. challenged claims 1-31 of USPN 8,889,083 owned by the University of Chicago. PTAB instituted trial on grounds of obviousness over two references. Each party relied on the testimony of one or more experts, and the Patent Owner challenged expert testimony as exceeding the proper scope of Petitioner’s Reply.

The technology at issue involved a device and method for pressurized transport of fluidic plugs, or droplets, in microfluidic systems used in chemical and biochemical reactions. The plug form of transport arises by injecting fluid containing reagents and a fluorinated surfactant into an immiscible fluorinated carrier fluid flowing in non-fluorinated microchannels of a microfluidic system. The system design ensures that the drops do not stick to the walls of the microchannels because the walls and the carrier fluid are chemically distinct and the fluorinated surfactant in the carrier fluid preferentially lowers the surface tension of the drop-carrier interface compared to the drop-wall interface, thereby minimizing contact between drops and wall.

PTAB reviewed challenges to Petitioner’s expert testimony and determined that expert testimony supporting Petitioner’s Reply Brief was improper in introducing a new theory of unpatentability.

Petitioner argued in its petition that the claims were obvious, in relevant part, because the required level of fluorinated surfactant was present in the microfluidic carrier fluid disclosed in a cited reference. Expert testimony supporting the Reply Brief argued, however, that determining the level of fluorinated surfactant would have involved routine optimization, implying that the prior art did not disclose the surfactant level, but could be modified to reach that level. PTAB also found a second attempt by Petitioner to change its argument when Petitioner shifted from arguing that a surfactant coating microchannel walls would result in the claim-recited surface tension relationships to arguing in its Reply Brief that surfactant in the carrier fluid would aid in controlling drop size and flow.

Citing the Trial Practice Guide and Intelligent Bio-Systems, Inc. v. Illumina Cambridge Ltd. (Fed. Cir. 2016), which we discussed here, the PTAB noted that when a reply brief or testimony exceeds the proper scope of a reply, the PTAB may refuse to consider the entire reply brief or new testimony, without parsing the paper to identify improper portions. In this case, the PTAB concluded that Petitioner raised new issues and arguments in its Reply Brief, exceeding its proper scope, but only excluded those portions of the Reply Brief that raised new issues or arguments. This case illustrates the risk to a petitioner in omitting a possible argument and supporting testimony in the petition, and then adding a new argument and testimony with its reply brief. Under such circumstances the PTAB may refuse to consider the new argument or, potentially, the entire reply brief.