Fig. 2: Electrical, mechanical, and acoustic performance validation of wf-UMP.
From: Wearable flexible ultrasound microneedle patch for cancer immunotherapy
a Schematic illustration of the active 1–3 piezo-unit in wf-UMP for US emission. b Impedance and phase angle spectra of 1–3 piezo-unit. The two peaks in the impedance spectrum are defined as the resonance frequency (fr) and the antiresonance frequency (fa), respectively. Inset presents the equivalent RLC circuit for 1–3 piezo-unit. c Comparison of thickness-mode electromechanical coupling coefficient and acoustic impedance between mKNN ceramic and its 1–3 piezo-unit. d Pulse-echo response and frequency spectrum of the 1–3 piezo-unit. e Impedance spectra of wf-UMP under different bending curvatures. f Optical image of a 2 × 2 array released from the 80% x-axis tensile strain. Scale bar, 2.5 mm. g 180° peeling test of the bioadhesive hydrogel on porcine skin. Scale bar, 1 cm. h FEA simulation of the acoustic field generated by a 1–3 piezo-unit. i FEA simulation of the acoustic field generated by wf-UMP. j Acoustic pressure of wf-UMP with increasing input voltages. k ISPTA and MI values of wf-UMP with increasing input voltages. l Thermal images of wf-UMP on an agarose hydrogel operated continuously for 30 min. Top, 0 min. Bottom: 30 min. Scale bars, 1 cm. m Comparison of drug delivery performance of wf-UMP on agarose hydrogels with/without US stimulation. Scale bars, 2 mm. n Confocal microscopy images of porcine skin treated with Rho B labeled wf-UMP with/without US stimulation at a depth of 328 μm. Scale bars, 250 μm.
