Fig. 1: An implantable piezoelectric ultrasound stimulator: ImPULS.
From: An implantable piezoelectric ultrasound stimulator (ImPULS) for deep brain activation
a Schematic illustration of an implantable piezoelectric ultrasound stimulator (ImPULS) implanted in a subcortical brain region of a wild-type mouse. A magnified view showing the activated neurons with ultrasound application. Schematic created with BioRender.com, released under a Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International license. b Schematic of a peeled view of the ImPULS, revealing each layer. The ImPULS is a piezoelectric micromachined ultrasound transducer (pMUT) structure where biocompatible potassium sodium niobate (KNN) is sandwiched between two thin SU-8 layers, and an air-filled cavity and a backing layer is formed underneath the piezoelectric thin-film membrane. c Optical image of the ImPULS assembled with flexible ACF cable and a custom printed circuit board (PCB) with a magnified view of the ImPULS probe (right, top inset) and further zoomed version of the tip of the probe (ultrasound unit) under a microscope (bottom, left inset). Scale bars, 5 mm, 2 mm, and 100 µm, respectively. d Colorized cross-sectional scanning electron microscope (SEM) image of the ImPULS. The device consists of (1) SU-8 encapsulation layer, (2) Top Pt electrode, (3) KNN thin film, (4) Bottom Au electrode, (5) SU-8 membrane layer, (6) Air-cavity, and (7) SU-8 backing layer. Scale bars, 20 µm and 500 nm, respectively.
