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Figure 7. Actuators, biosensors and transducers based on biodegradable piezoelectric materials. (A) Optical Image of the grasping of a polystyrene bead cluster using PLLA actuator treated with supercritical-CO₂. Reproduced with permission^[74]. Copyright 2010, John Wiley and Sons. (B) Pressure signals detected by the PLLA sensor in the mouse abdominal diaphragm, black line and red line represent live mouse under anesthesia and being euthanized, respectively. Reproduced with permission^[67]. Copyright 2018, National Academy of Science. (C) Structure of the biodegradable ferroelectric gelatin electronic skin (e-skin) and the image of the pressure distribution when placed on an irregular object. Reproduced with permission^[49]. Copyright 2021, John Wiley and Sons. (D) Schematic illustration of the structure of silk fibroin based pressure sensor with micro-structured electrode and the comparison of voltage response symbols and linear fits between silk sensor with micro-structured electrode and flat electrode. Reproduced with permission^[113]. Copyright 2022, Elsevier. (E) Schematic illustration of the in vivo experiment of PLLA nanofiber transducer to overcome the blood-brain barrier. (F) The autofluorescent signal of blood protein (green stain) at the coronal section (C2) from the brains of mice that received ultrasound (US) from the piezoelectric PLLA transducer (left, 4000 rpm) and the non-piezoelectric PLLA transducer (right). (E and F) reproduced with permission^[72]. Copyright 2020, National Academy of Science.