To utilise this method for wirelessly growing in-situ bioelectronics, it is necessary to control microwire growth in the presence of biology. As we have demonstrated, microwire growth is possible in a 2D space, however, the next stage requires microwire growth in a 3D cell culture model. Glioblastoma cells (U251) were chosen for future applications of in vivo grown bioelectronics in neural-based therapeutics. Spheroids were attached to BPEs between two FEs (1 mm apart) using a coating of poly-D-lysine. Average spheroid diameter ranged from ~100-400 mm, hence 2-3 spheroids were attached between FEs that were 1mm apart. AC electrical stimulation was then used to attempt wire growth in the presence of the spheroids where; identical electrical inputs as above were used. As shown in Figure , MW growth was possible at 50 V (0.5 kV/cm), 1 MHz; however, these were limited in length (50mm) and required high potential, resulting in cell clumping. It was expected that wire growth was not possible at other inputs due to spheroids introducing high impedance to the BES. As AC stimulation was not capable of growing MWs in the presence of cell spheroids, DC stimulation was pursued. As shown in Figure , MW growth was successful when using 50 V (0.5 kV/cm) of DC applied to a single spheroid of approximately 800 µm in diameter. It can be observed that MWs successfully grew around and underneath spheroids with a diameter of 7.89 ± 0.6 µm (n=50), which is similar to electrical inputs without cells (Figure ). This suggests that the wire structure is similar to studies formed from AgNPs alone. To approximate the effect of MW growth on cell viability, trypan blue was applied to spheroids (Figure ). This suggested that a small population of cells had broken away from the surface of the spheroid and were not viable; neverthelessthe main cell population's membranes appeared still intact.