Fabrication and characterization of AlN-based flexible piezoelectric pressure sensor integrated into an implantable artificial pancreas

Abstract

This study reports on the fabrication and characterization of an event detection subsystem composed of a flexible piezoelectric pressure sensor and the electronic interface to be integrated into an implantable artificial pancreas (IAP) for diabetic patients. The developed sensor is made of an AlN layer, sandwiched between two Ti electrodes, sputtered on Kapton substrate, with a preferential orientation along c-axis which guarantees the best piezoelectric response. The IAP is made of an intestinal wall-interfaced refilling module, able to dock an ingestible insulin capsule. A linearly actuated needle punches the duodenum tissue and then the PDMS capsule to transfer the insulin to an implanted reservoir. The device is located at the connection of the needle with the linear actuator to reliably detect the occurred punching of the insulin-filled capsule. Finite Element Analysis (FEA) simulations were performed to evaluate the piezoelectric charge generated for increasing loads in the range of interest, applied on both the sensor full-area and footprint area of the Hamilton needle used for the capsule punching. The sensor-interface circuit was simulated to estimate the output voltage that can be obtained in real operating conditions. The characterization results confirmed a high device sensitivity during the punching, in the low forces (0–4 N) and low actuator speed (2–3 mm/s) ranges of interest, meeting the requirement of the research objective. The choice of a piezoelectric pressure sensor is particularly strategic in the medical field due to the request of self-powered implantable devices which do not need any external power source to output a signal and harvest energy from natural sources around the patient.

Flexible Tactile Sensors Using AlN and MOSFETs Based Ultra-Thin Chips

“…This leads to a rapid decrease in the piezo output which finally reaches to zero. When the force is released, the piezoelectric polarisation disappears, giving rise to a negative peak (electrons flows in backwards direction to achieve the new equilibrium) [47].…”

“…as it exhibits efficient piezoelectric and dielectric properties, high thermal stability, as well as low dielectric loss tangent and high signal to noise ratio [35][36][37]. Additionally, no poling or stretching is needed [38].…”

Nanoarchitectonics for Wide Bandgap Semiconductor Nanowires: Toward the Next Generation of Nanoelectromechanical Systems for Environmental Monitoring

“…[256][257][258][259][260] However, the fabrication of high-performance pressure sensors based on WBG semiconductor nanowires, especially for SiC, group III-nitrides, and diamond, are very rare. [261][262][263] For instance, Phan et al reported an effective approach to develop highly sensitive pressure sensors employing 3C-SiC nanowires fabricated at the center of a dogbone-like structure. [261] Figure 12a shows a photograph of SiC nanowire-based pressure sensors mounted on an acrylic holder.…”

Conformal, Ultra‐thin Skin‐Contact‐Actuated Hybrid Piezo/Triboelectric Wearable Sensor Based on AlN and Parylene‐Encapsulated Elastomeric Blend

“…[ 40 ] PSs have been applied for monitoring physico‐chemical health parameters or as nanogenerators (PENGs) for harvesting human energy to supply portable/implantable biomedical devices. [ 41,42 ] In this work, a thin film of transparent lead‐free inorganic aluminum nitride (AlN) piezo‐ceramic [ 43,44 ] has been employed as piezoelectric material on flexible polyimide (PI), chosen for its high temperature, mechanical and chemical stability. [ 45,46 ] AlN exhibits advantageous properties: heat‐ and humidity‐resistance, [ 47 ] biocompatibility, [ 40,48 ] CMOS compatibility, good piezoelectric, and dielectric properties both on rigid and flexible substrates.…”