###### Abstract
Unlike traditional forms of linear EK, such as unidirectional DC electro-osmotic (EO) plug-like pump-fluid motion [27, 28, 29], nonlinear EHD survives well and appears as a series of micro-vortices of variable rotating directions after time-averaging operations under AC actuation [30, 31, 32, 33, 34, 35]. In this way, nonlinear EK effects, in which the electrical driving force scales nonlinearly with the applied voltage, tend to enable more flexible control of localized flow behavior and are suitable for some intriguing microfluidic applications, such as medium transport [36, 37, 38, 39, 40], analyte mixing [41, 42, 43], and sample enrichment [31, 44, 45, 46, 47] in confined channels. Considering the high degree of freedom controllability achieved by tuning the magnitude, phase sequence, and angular frequency of the imposed AC voltage signal, both AC electrothermal (ACET)-induced flow and induced-charge electro-osmosis (ICEO) have received increasing attention from the microfluidics community, serving as the two most classical examples of nonlinear AC electro-hydrodynamics. Unlike ACET, which behaves as a type of bulk electroconvection originating from induced space charges under Maxwell-Wagner structural polarization, the induced-charge electrokinetic (ICEK) phenomenon arises due to voltage-driven diffuse-charge dynamics around ideally or even weakly polarizable solid surfaces immersed in conducting fluids [48]. The ICEK occurs when a background electric field \(E\) induces a Debye screening cloud at polarizable solid/liquid interfaces and subsequently forces its own induced bipolar diffuse charges inside the induced double layer (IDL) into an active ICEO streaming flow. As the characteristic thickness of IDL containing excessive mobile counterions shrinks with the ionic strength, ICEO is especially efficient for manipulating low-conductivity liquid solutions [49]. The adjustment of asymmetry in the material composition of polarizable solid objects serves as a simple way of regulating the mechanical behavior of ICEO. For example, a typical scenario in which ICEO is engendered is the evolution of a quadrupolar ICEO vortex flow field in opposite rotating directions next to an ideally polarizable metal cylinder, usually placed in a background low-frequency AC electric field [50]. Based on this device geometry, [PERSON] et al. [51] recently suggested the use of an array of metal-dielectric Janus micropillars of asymmetric interfacial polarizability to break the symmetry of a classical ICEO vortex flow field next to conducting posts so that an external AC-voltage difference applied across the array of discrete Janus posts drives unidirectional ICEO flow along the channel length direction, allowing a net pump motion perpendicular to the imposed electric field. In our current work, we developed an effective microfluidic technology of dual functionality in the simultaneous active pumping and mixing of analytes via pure ICEO without any external moving parts, as shown in Figure 1A,B. The fully automated microfluidic pump and mixer driven by ICEO are achievable by a delicate combination of horizontal flow symmetry breaking around an originally unbiased metal-dielectric Janus cylinder (Figure 1C) and transversal counterpart via the AC field-effect control of ICEO (Figure 1D,E). By applying a biased AC gate voltage to the metal phase of the central Janus micropillar placed between a pair of 3D sidewall driving electrodes (DE) in a straight microchannel (Figure 1A), a new net rotating behavior \(\mathrm{u_{y}}\) was created for lateral ICEO streaming parallel to the applied field lines due to the AC field-effect flow control (Figure 1D,E), apart from the existing horizontal pump motion \(\mathrm{u_{x}}\) due to the symmetry breaking in the ICEO caused by the inhomogeneous polarizability of the Janus pillar along the channel's length (Figure 1C).