Periodic Reporting for period 1 - UNOPIEZO (Unobtrusive printed piezoelectric sensors for non-invasive biosignal monitoring)
Berichtszeitraum: 2021-10-01 bis 2022-12-31
Continuous, large-scale health monitoring of cardiovascular disease (CVD) risk population carries significant benefits to the society (e.g. decreased mortality and treatment costs due to early disease detection), but is currently not possible because of the lack of unobtrusive, affordable and accurate bio-signal sensors. This MSCA project proposes to solve these issues through development of ultra-thin (< 10 µm thick) sensors which attach conformably to the skin and improve the mechanical coupling between the skin-sensor interface thereby resulting in highly unobtrusive user experience and accurate signal reproduction. Furthermore, cost-effective additive fabrication technologies are employed to make the devices affordable and to enable their mass-scale fabrication required for large-scale screening of the whole risk population.
The overall research objectives of the project are:
RO1: Determination of material parameters for modelling and application for ethical permission
RO2: Development of engineering design rules for printed ultra-thin piezoelectric sensors
RO3: Development of printing processes to fabricate the designed structures
RO4: Demonstration of device performance in bio-signal measurement
The expected outcomes of the ROs are:
RO1: Determination of mechanical, electrical and piezoelectric material parameters required for modelling in RO2. Start of application procedure for ethical permission for human studies.
RO2: Fundamental understanding how to maximize the sensitivity through material choices (e.g. substrate elastic moduli, plain strain bending modulus), manipulation of the device dimensions (e.g. piezoelectric material thickness, substrate vs. piezoelectric thickness ratio), and device architecture (e.g. charge collector layout). Understanding how to improve mechanical coupling between sensor and skin. Implemented through a finite element model (FEM). Design and fabrication of ultra-thin battery free data transmission unit (DTU).
RO3: Printed unobtrusive, affordable and accurate ultra-thin piezoelectric sensors
RO4: Clinically accurate pulse wave signal measured from the carotid/radial artery. Verification done using simultaneous measurement with state-of-the art devices used currently in hospitals.
The overall research objectives of the project are:
RO1: Determination of material parameters for modelling and application for ethical permission
RO2: Development of engineering design rules for printed ultra-thin piezoelectric sensors
RO3: Development of printing processes to fabricate the designed structures
RO4: Demonstration of device performance in bio-signal measurement
The expected outcomes of the ROs are:
RO1: Determination of mechanical, electrical and piezoelectric material parameters required for modelling in RO2. Start of application procedure for ethical permission for human studies.
RO2: Fundamental understanding how to maximize the sensitivity through material choices (e.g. substrate elastic moduli, plain strain bending modulus), manipulation of the device dimensions (e.g. piezoelectric material thickness, substrate vs. piezoelectric thickness ratio), and device architecture (e.g. charge collector layout). Understanding how to improve mechanical coupling between sensor and skin. Implemented through a finite element model (FEM). Design and fabrication of ultra-thin battery free data transmission unit (DTU).
RO3: Printed unobtrusive, affordable and accurate ultra-thin piezoelectric sensors
RO4: Clinically accurate pulse wave signal measured from the carotid/radial artery. Verification done using simultaneous measurement with state-of-the art devices used currently in hospitals.
The research done in this reporting period was related to the RO1 and RO2 and the main outcomes were:
RO1: 1) Material parameters for FE-modelling were determined from the literature and 2) ethical permission for clinical study was submitted to Tampere University Hospital (Tampereen Yliopistollinen Sairaala, TAYS) ethical review committee.
RO2: 1) Engineering design rules were implemented for an ultra-thin piezoelectric sensors using finite element modelling. Specificially a FE-model was generated for an interdigitated electrode based ultra-thin piezoelectric sensor and it was used to optimize the sensor geometry and poling condition; the study was accepted for publication in IOP Flexible and Printed Electronics 2) Modification and optimization of an existing data transmission unit (DTU) for the piezoelectric sensor.
Following is a more detailed summary of the actions taken to achieve these outcomes:
RO1:
1) Potential printable piezoelectric materials were surveyed from the literature and tested. Relevant material parameters for the FE-model were searched from the literature.
2) The first version of the application for the clinical trial was completed and submitted in Dec. 2021 under the guidance of Associate Professor Antti Vehkaoja and Chief Vascular Surgeon, Professor Niku Oksala from Faculty of Medicine and Health Technology, Tampere University. The first draft received few comments which need to be fixed by the end of Jan. 2023, but in general the review was favorable. The first version is available in the Grant Management System under the title “101022433_Deliverable_2_(H - Requirement No. 2)”.
RO2:
1) We studied the optimization of the geometry and poling condition of an interdigitated electrode based pulse wave sensor so as to maximize its sensitivity. Specifically, we developed an FE-model for ultra-thin piezoelectric poly(vinylidene-trifluoroethylene) (PVDF-TrFE) sensor with interdigitated electrodes (IDE) which included the effect of a non-homogenous poling field determined via combination of experimental and numerical methods. The study has passed peer-review and is accepted for publication in IOP Flexible and Printed Electronics journal (DOI: 10.1088/2058-8585/acb36b).
2) We modified an existing data transmission unit (DTU) to be used together with a ultra-thin piezoelectric sensor. The main modification was the addition a charge amplifier to the existing DTU. This included the optimization of the amplifier bandwidth with an artificial heart test setup (AHTS). Specifically, the AHTS was used to generate a pulse wave which was measured simultaneously with an internal reference sensor of the ATHS and a printed ultra-thin P(VDF-TrFE) based piezoelectric sensor. A comparison of the pulse wave shape showed that the best correspondence between the printed and reference sensor was achieved by reducing the low cutoff frequency of the charge amplifier to ~50 mHz.
RO1: 1) Material parameters for FE-modelling were determined from the literature and 2) ethical permission for clinical study was submitted to Tampere University Hospital (Tampereen Yliopistollinen Sairaala, TAYS) ethical review committee.
RO2: 1) Engineering design rules were implemented for an ultra-thin piezoelectric sensors using finite element modelling. Specificially a FE-model was generated for an interdigitated electrode based ultra-thin piezoelectric sensor and it was used to optimize the sensor geometry and poling condition; the study was accepted for publication in IOP Flexible and Printed Electronics 2) Modification and optimization of an existing data transmission unit (DTU) for the piezoelectric sensor.
Following is a more detailed summary of the actions taken to achieve these outcomes:
RO1:
1) Potential printable piezoelectric materials were surveyed from the literature and tested. Relevant material parameters for the FE-model were searched from the literature.
2) The first version of the application for the clinical trial was completed and submitted in Dec. 2021 under the guidance of Associate Professor Antti Vehkaoja and Chief Vascular Surgeon, Professor Niku Oksala from Faculty of Medicine and Health Technology, Tampere University. The first draft received few comments which need to be fixed by the end of Jan. 2023, but in general the review was favorable. The first version is available in the Grant Management System under the title “101022433_Deliverable_2_(H - Requirement No. 2)”.
RO2:
1) We studied the optimization of the geometry and poling condition of an interdigitated electrode based pulse wave sensor so as to maximize its sensitivity. Specifically, we developed an FE-model for ultra-thin piezoelectric poly(vinylidene-trifluoroethylene) (PVDF-TrFE) sensor with interdigitated electrodes (IDE) which included the effect of a non-homogenous poling field determined via combination of experimental and numerical methods. The study has passed peer-review and is accepted for publication in IOP Flexible and Printed Electronics journal (DOI: 10.1088/2058-8585/acb36b).
2) We modified an existing data transmission unit (DTU) to be used together with a ultra-thin piezoelectric sensor. The main modification was the addition a charge amplifier to the existing DTU. This included the optimization of the amplifier bandwidth with an artificial heart test setup (AHTS). Specifically, the AHTS was used to generate a pulse wave which was measured simultaneously with an internal reference sensor of the ATHS and a printed ultra-thin P(VDF-TrFE) based piezoelectric sensor. A comparison of the pulse wave shape showed that the best correspondence between the printed and reference sensor was achieved by reducing the low cutoff frequency of the charge amplifier to ~50 mHz.
According to the project plan, following beyond the current state-of-the-art progress should have been achieved by the end of the project:
1. Enhancing the bio-signal sensor accuracy through mechanical modelling driven sensor design
2. Enhancing the bio-signal sensor unobtrusiveness through use of ultra-thin form factor
3. Enhancing the bio-signal sensor affordability through development of highly scalable additive fabrication process
4. Enabling large scale and continuous screening of entire CVD risk population
Currently, the beyond state of the art status has been achieved regarding the first goal “Enhancing the bio-signal sensor accuracy through mechanical modelling driven sensor design”. Specifically, this has been achieved through the completion of the study related to optimization of the geometry and poling condition of an interdigitated electrode based pulse wave sensor (see more detailed explanation in previous section and technical report). This study should pave the way towards easier FE-model based optimization strategy of the piezoelectric sensors thereby providing an important step towards realizing high sensitivity ultra-thin piezoelectric devices.
By the end of the project we expect to develop a pulse wave measurement system consisting of a performance optimized, ultra-thin and printed piezoelectric sensor, and the wireless DTU. We also expect to show that the developed system can record the pulse wave with sufficient accuracy so that clinically relevant information (regarding CVDs) can be extracted from the obtained pulse wave signal. That is, we expect to have improved the state of the art also regarding goals 2 to 4.
As mentioned in the first section, these developments should enable continuous, large-scale health monitoring of CVD risk population which carries significant benefits to the society (e.g. decreased mortality and treatment costs due to early disease detection), but is currently not possible because of the lack of unobtrusive, affordable and accurate bio-signal sensors.
1. Enhancing the bio-signal sensor accuracy through mechanical modelling driven sensor design
2. Enhancing the bio-signal sensor unobtrusiveness through use of ultra-thin form factor
3. Enhancing the bio-signal sensor affordability through development of highly scalable additive fabrication process
4. Enabling large scale and continuous screening of entire CVD risk population
Currently, the beyond state of the art status has been achieved regarding the first goal “Enhancing the bio-signal sensor accuracy through mechanical modelling driven sensor design”. Specifically, this has been achieved through the completion of the study related to optimization of the geometry and poling condition of an interdigitated electrode based pulse wave sensor (see more detailed explanation in previous section and technical report). This study should pave the way towards easier FE-model based optimization strategy of the piezoelectric sensors thereby providing an important step towards realizing high sensitivity ultra-thin piezoelectric devices.
By the end of the project we expect to develop a pulse wave measurement system consisting of a performance optimized, ultra-thin and printed piezoelectric sensor, and the wireless DTU. We also expect to show that the developed system can record the pulse wave with sufficient accuracy so that clinically relevant information (regarding CVDs) can be extracted from the obtained pulse wave signal. That is, we expect to have improved the state of the art also regarding goals 2 to 4.
As mentioned in the first section, these developments should enable continuous, large-scale health monitoring of CVD risk population which carries significant benefits to the society (e.g. decreased mortality and treatment costs due to early disease detection), but is currently not possible because of the lack of unobtrusive, affordable and accurate bio-signal sensors.