2b, where the laser beam is placed on the drain electrode, the measured photon flux in the source of the EXAT would require a source current $I_c \approx 50$ nA. This current is two orders of magnitude larger than the measured source current (of 0.5 nA) under the same illumination conditions, showing that both electrons and holes must have been transported by the SAW. Similar results were obtained for the current in the drain electrode, where recombination takes place at the edge of the drain area.

Acoustic exciton multiplexer - EXAM {#SecEXAM}
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We now introduce the EXAM (cf. micrograph of Fig. \[Fig2\](a)), a device capable of routing IX fluids between different input/output ports ($I/O_{i}$, labeled by the port index i=1,...,8). Each I/O port contains an IDT (not shown) to generate an outgoing SAW beam as well as an exciton acoustic transistor (EXAT, cf. Fig. \[EXAT\](a)) to control the IX flux between the EXAT source area and the common drain region, where multiplexing takes place. In each I/O port, an input optical signal (represented by a laser incident on the source electrode of EXAT$_1$ in Fig. \[Fig2\](a)) can be converted into IXs and stored in the EXAT source electrode. Alternatively, 