3D µEFPocket for Multimodal Communications with Brain Organoids

Human brain organoids are powerful three-dimensional models for studying neural development, disease mechanisms, and pharmacological responses, but precise spatiotemporal chemical modulation and activity recording within intact organoids and in a simultaneous fashion is difficult due to their three-dimensional (3D) complexities. Here, we introduce the microElectroFluidicPocket (µEFPocket), a conformal, ultrathin microfluidic 3D biointerface that integrates microscale spatiotemporal control of chemical and electrical stimulation in human cortical organoids with simultaneous optical and electrical readout. Fabricated entirely from parylene C using standard wafer-scale deposition, photolithography, and etching, µEFPockets form integrated, mechanically compliant architectures that wrap around spherical organoids without attachment factors, enabling repeated use of the same organoid. Engineered and independently addressable microchannels enable localized, time-locked delivery of neurotransmitters with hundreds-micron spatial resolution and second-level temporal control while preserving global culture conditions. Using glutamate delivery or electrical stimulation of GCaMP-expressing human cortical organoids, we demonstrate spatially localized calcium responses at regional and single-neuron resolution, revealing network propagation and stimulus-dependent adaptation. This scalable platform provides a foundation for spatially patterned pharmacology, multimodal biointerfaces, and closed-loop functional assays in organoids.