fig8

Figure 8. Implantable flexible electrodes for sensing biosignals. (A) The exploded-view drawing of the ultra-large tunable stiffness electrodes enabled by LMs. Reproduced with permission^[132]. Copyright 2019, Elsevier B.V; (B) The stiff sate electrode can translate into soft sate due to the melting of LMs, and the insert picture shows the outlet of the drug delivery channel and Pt electrodes of the probe tip. Reproduced with permission^[132]. Copyright 2019, Elsevier B.V; (C) Schematic illustration of the highly stretchable electrodes for in vivo epicardial recording on a rabbit. Reproduced with permission^[134]. Copyright 2022, American Association for the Advancement of Science; (D) The electrodes can be conformally attached to the right ventricle for long-term monitoring of the electrocardio; and (E) shows the representative electrogram for 20 min of monitoring. Reproduced with permission^[134]. Copyright 2022, American Association for the Advancement of Science; (F) Photo of the stretched neural electrode arrays prepared by depositing Au film on LM-PDMS composite. Reproduced with permission^[135]. Copyright 2022, All authors; (G) Intraoperative image of the neural electrode arrays for in vivo recording of ECoG signals, showing the high flexibility of the electrode to be in contact with the cerebral cortex of the rat; and (H) ECoG signals of a healthy rat under normal state and epileptic state. Reproduced with permission^[135]. Copyright 2022, All authors. ECoG: Electrocorticogram; LM: liquid metal; PDMS: polydimethylsiloxane; PEDOT:PSS: poly 3,4-ethylene dioxythiophene : polystyrene sulfonate; SEBS: styrene-ethylene-butylene-styrene.