Full Fabrication and Packaging of an Implantable Multi-Panel Device for Monitoring of Metabolites in Small Animals

Abstract

Abstract-In this work, we show the realization of a fully-implantable device for monitoring free-moving small animals. The device integrates a microfabricated sensing platform, a coil for power and data transmission and two custom designed integrated circuits. The device is intended to be implanted in mice, free to move in a cage, to monitor the concentration of metabolites. We show the system level design of each block of the device, and we present the fabrication of the passive sensing platform and its employment for the electrochemical detection of endogenous and exogenous metabolites. Moreover, we describe the assembly of the device to test the biocompatibility of the materials used for the microfabrication. To ensure biocompatibility, an epoxy enhanced polyurethane membrane was used to cover the device. We proved through an in-vitro characterization that the membrane was capable to retain enzyme activity up to 35 days. After 30 days of implant in mice, in-vivo experiments proved that the membrane promotes the integration of the sensor with the surrounding tissue, as demonstrated by the low inflammation level at the implant site.

A System for Wireless Power Transfer and Data Communication of Long-Term Bio-Monitoring

“…A bio-compatible Silicone (NuSil MED-6233) was used to cover the edges and to fill the spaces between the platform and the PCB. A 30 days of in-vivo experiment also verifies the bio-compatibility of the package with the low inflammation level at the implant site [25]. Fig.…”

“…The platform measures 12×11 mm in order to fit the size of the coil (12×12 mm) and the wire bonding. The platform hosts an array of four working electrodes (WEs), sharing a common counter electrode (CE) and a reference electrode (RE), with the addition of a temperature sensor and a pH sensor [25].…”

“…the presence of nano-structured materials, proteins, mediators, membranes, etc. However, we solved this problem by finding the right combination of nano-materials, and proteins for each molecule of interest [25]. Moreover, the integration of the ICs on the PCB is another important challenge for the system implementation.…”

Biocompatible packagings for fully implantable multi-panel devices for remote monitoring of metabolism

“…In this paper we compare three different packaging realized with different shape, size and with different materials. However, they all share some common features: (i) MWCNTs were entrapped in a chitosan matrix to prevent the potential toxicity due to their nano-particle nature; (ii) to prevent the corrosion of electronic components due to the contact with biologic fluids, and to prevent the leaking of potential hazardous substances, a coating of Parylene C was deposited [8,9]; (iii) a biocompatible packaging was realized, as, for an implantable sensor, it is essential for a correct wound healing, and for ensuring prolonged sensor functionality. The main differences between the three systems are: (i) the shape of the device; (ii) the shape of the packaging in silicone; (iii) the composition of the membrane that covers the sensors; (iv) the composition of the external packaging.…”

“…The platforms measure 12x11 mm, in order to fit the size of the coil (12x12 mm) and the wire bonding. The platform hosts an array of four independent cells in the three-electrode configuration, WE, CE and RE, all made in Pt [9].…”