Fabrication of an Integrated, Flexible, Wireless Pressure Sensor Array for the Monitoring of Ventricular Pressure

This work presents the design, fabrication, and rigorous validation of a flexible, wireless, capacitive pressure sensor for the full-range continuous monitoring of ventricular pressure. The proposed system consists of an implantable set and an external readout device; both modules were designed to f...

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Main Authors: Natiely Hernández-Sebastián, Daniela Diaz-Alonso, Bernardino Barrientos-García, Francisco Javier Renero-Carrillo, Wilfrido Calleja-Arriaga
Format: Article
Language:English
Published: MDPI AG 2024-11-01
Series:Micromachines
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Online Access:https://www.mdpi.com/2072-666X/15/12/1435
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author Natiely Hernández-Sebastián
Daniela Diaz-Alonso
Bernardino Barrientos-García
Francisco Javier Renero-Carrillo
Wilfrido Calleja-Arriaga
author_facet Natiely Hernández-Sebastián
Daniela Diaz-Alonso
Bernardino Barrientos-García
Francisco Javier Renero-Carrillo
Wilfrido Calleja-Arriaga
author_sort Natiely Hernández-Sebastián
collection DOAJ
description This work presents the design, fabrication, and rigorous validation of a flexible, wireless, capacitive pressure sensor for the full-range continuous monitoring of ventricular pressure. The proposed system consists of an implantable set and an external readout device; both modules were designed to form an RCL resonant circuit for passive, wireless pressure sensing and signal retrieving. Using surface micromachining and flexible electronics techniques, a two-variable capacitor array and a dual-layer planar coil were integrated into a flexible ergonomic substrate, avoiding hybrid-like connections in the implantable set. The proposed arrangement (capacitor array and dual-layer coil) allows us to optimize the operation pressure range and sensing distance. The use of polyimide as both the flexible substrate and the passivation material is a key feature, ensuring a biocompatible, implantable set that is mechanically flexible and can be folded to a compact size to achieve minimally invasive implantation. An external readout device has also been developed using a discrete printed circuit board (PCB) approach to support pressure measurements. The pressure responsivity of the sensor was validated to the laboratory level using a controlled pressure chamber. The results obtained show that the capacitance value of the sensor changed from 5.68 pF to 33.26 pF as the pressure varied from 0 to 300 mmHg. Correspondingly, the resonance frequency of the implantable set shifted from 12.75 MHz to 5.27 MHz. The sensitivity of the capacitive sensor was approximately 0.58 pF/mmHg and the typical response time was 220 ms. The wireless system performance was evaluated in both air and synthetic biological tissue using a Maxwell–Wien bridge circuit. The results showed a sensing distance longer than 3.5 cm, even under moderate misalignment conditions (up to 1.5 cm). The output voltage was successfully measured, ranging from 502.54 mV to 538.29 mV, throughout the full pressure range, with a measurement error of ±2.2 mV.
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spelling doaj-art-e69450a5d52e41128d431e9b7f0681c12024-12-27T14:40:40ZengMDPI AGMicromachines2072-666X2024-11-011512143510.3390/mi15121435Fabrication of an Integrated, Flexible, Wireless Pressure Sensor Array for the Monitoring of Ventricular PressureNatiely Hernández-Sebastián0Daniela Diaz-Alonso1Bernardino Barrientos-García2Francisco Javier Renero-Carrillo3Wilfrido Calleja-Arriaga4Centro de Investigaciones en Óptica, A.C., CIO, Leon 37150, MexicoCD-MEMS INAOE, Puebla 72840, MexicoCentro de Investigaciones en Óptica, A.C., CIO, Leon 37150, MexicoInstituto Nacional de Astrofísica, Óptica y Electrónica—INAOE, Puebla 72840, MexicoInstituto Nacional de Astrofísica, Óptica y Electrónica—INAOE, Puebla 72840, MexicoThis work presents the design, fabrication, and rigorous validation of a flexible, wireless, capacitive pressure sensor for the full-range continuous monitoring of ventricular pressure. The proposed system consists of an implantable set and an external readout device; both modules were designed to form an RCL resonant circuit for passive, wireless pressure sensing and signal retrieving. Using surface micromachining and flexible electronics techniques, a two-variable capacitor array and a dual-layer planar coil were integrated into a flexible ergonomic substrate, avoiding hybrid-like connections in the implantable set. The proposed arrangement (capacitor array and dual-layer coil) allows us to optimize the operation pressure range and sensing distance. The use of polyimide as both the flexible substrate and the passivation material is a key feature, ensuring a biocompatible, implantable set that is mechanically flexible and can be folded to a compact size to achieve minimally invasive implantation. An external readout device has also been developed using a discrete printed circuit board (PCB) approach to support pressure measurements. The pressure responsivity of the sensor was validated to the laboratory level using a controlled pressure chamber. The results obtained show that the capacitance value of the sensor changed from 5.68 pF to 33.26 pF as the pressure varied from 0 to 300 mmHg. Correspondingly, the resonance frequency of the implantable set shifted from 12.75 MHz to 5.27 MHz. The sensitivity of the capacitive sensor was approximately 0.58 pF/mmHg and the typical response time was 220 ms. The wireless system performance was evaluated in both air and synthetic biological tissue using a Maxwell–Wien bridge circuit. The results showed a sensing distance longer than 3.5 cm, even under moderate misalignment conditions (up to 1.5 cm). The output voltage was successfully measured, ranging from 502.54 mV to 538.29 mV, throughout the full pressure range, with a measurement error of ±2.2 mV.https://www.mdpi.com/2072-666X/15/12/1435capacitive pressure sensorflexible electronicspassive wireless systemventricular pressure monitoringimplantable BioMEMS
spellingShingle Natiely Hernández-Sebastián
Daniela Diaz-Alonso
Bernardino Barrientos-García
Francisco Javier Renero-Carrillo
Wilfrido Calleja-Arriaga
Fabrication of an Integrated, Flexible, Wireless Pressure Sensor Array for the Monitoring of Ventricular Pressure
Micromachines
capacitive pressure sensor
flexible electronics
passive wireless system
ventricular pressure monitoring
implantable BioMEMS
title Fabrication of an Integrated, Flexible, Wireless Pressure Sensor Array for the Monitoring of Ventricular Pressure
title_full Fabrication of an Integrated, Flexible, Wireless Pressure Sensor Array for the Monitoring of Ventricular Pressure
title_fullStr Fabrication of an Integrated, Flexible, Wireless Pressure Sensor Array for the Monitoring of Ventricular Pressure
title_full_unstemmed Fabrication of an Integrated, Flexible, Wireless Pressure Sensor Array for the Monitoring of Ventricular Pressure
title_short Fabrication of an Integrated, Flexible, Wireless Pressure Sensor Array for the Monitoring of Ventricular Pressure
title_sort fabrication of an integrated flexible wireless pressure sensor array for the monitoring of ventricular pressure
topic capacitive pressure sensor
flexible electronics
passive wireless system
ventricular pressure monitoring
implantable BioMEMS
url https://www.mdpi.com/2072-666X/15/12/1435
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AT bernardinobarrientosgarcia fabricationofanintegratedflexiblewirelesspressuresensorarrayforthemonitoringofventricularpressure
AT franciscojavierrenerocarrillo fabricationofanintegratedflexiblewirelesspressuresensorarrayforthemonitoringofventricularpressure
AT wilfridocallejaarriaga fabricationofanintegratedflexiblewirelesspressuresensorarrayforthemonitoringofventricularpressure