Etienne Lemaire
email: etienne.lemaire@ecam.fr

Jean-Baptiste De Vaulx

Nicolas Vaissiere

Thomas Delin

Atilla Atli

"Fablab ready" 3D printed piezoelectric composites

I. INTRODUCTION

Additive manufacturing enables the development of lowcost environmental sensing systems for smart packaging [1]. However, for widespread deployment of IoT, the development of eco-friendly disposable smart labels is necessary [2]. Previous works on green piezoelectric devices have shown the impregnation of biodegradable Rochelle salt (RS) crystals into cellulose sheets or naturally orientated capillaries of wood [3,4], which produced eco-friendly composite bulk devices. Here we propose an additive manufacturing process combining conventional PLA 3D printing and liquid phase epitaxy. The obtained devices can be used as disposable harvester or resonators with quite high quality factors and low energy budget.

II. METHOD

The piezoelectric samples were produced with the following method. First, disk shaped PLA matrices (Figure 1) were printed by using Ultimaker 3D printer (V1.1). PLA filament was also provided by the same company. In parallel, some RS crystal seeds were grown in order to get large single crystals (at least 2 cm wide). The crystal growth was done in an over saturated solution at room temperature (around 21°C) by mixing deionized water and RS powder provided by APC pure. Then a RS seed was attached a PLA matrix on one side and deeped into over saturated solution at 10°C in order to initiate the liquid phase crystal epitaxy through the PLA disk as shown in Fig. 1. Once the PLA sample was completely embedded into the growing RS crystal (after 36 to 48 hours), it was removed from the solution. Then the exceeded RS from PLA matrix was removed by carefully cutting the RS crystal close to both sides of PLA disk and polished by sand paper until the PLA matrix surfaces appear again. Finally, electrodes were placed on the sample. Two aluminum disks (10 µm thin) were cut into commercial aluminum foil and stuck on both sides of the disk with Bare conductive ink (commercial name: "electric paint"). As previously mentioned, this manufacturing process is simple and feasible in any Fablab without any sophisticated equipment. Both energy and financial budgets of such a process are low compared to standard piezoelectric ceramic or even organic samples in terms of costs and complexity. Then electrical characterizations were performed in order to get the resonance behavior of the manufactured piezoelectric disk samples. We have measured the impedance spectrum of the devices using E4980A, Keysight impedance analyser.

III. RESULTS

All samples emitted audible acoustic waves when driven electrically from 1 to 15 kHz. Moreover, the clear electromechanical coupling modes were observed in the admittance spectra of all manufactured samples. In particular, some RS based disks showed admittance spectra with wellidentified resonant frequencies in ambient condition (Fig. 2).

In order to evaluate performance and reproducibility of our process we calculated the resonant frequency (fr [Hz]), quality (Q) and coupling factors (kp). RS/PLA composite disks exhibit high resonant frequencies and Q factors. First resonant mode is around 47 kHz, and average quality factor is close to 80 (Fig. 3). Therefore, these devices exhibit better performances compared to the ones obtained in previous works [3,4]. Coupling factors, close to 0.2, are encouraging in order to target energy harvesting in the future. Nevertheless, the standard deviations of these sets of parameters are still quite high. This indicates that our manufacturing process can still be improved in order to get better reproducibility.

IV. CONCLUSION

In conclusion, we have successfully manufactured RS/PLA composite piezoelectric transducers using 3D printing of a PLA matrix on which the RS piezoelectric crystals were grown by liquid phase epitaxy. The piezoelectric performance was improved on these new samples compared to the previous results [3,4]. This new process allows to manufacture at low cost, and in any fablab, of biodegradable piezoelectric resonators with quality factor up to 110. There is a nice potential for these elements to be implemented in smart objects for energy harvesting or sensing applications with eco-friendly considerations. In facts, the energy budget needed to manufacture such RS/PLA composite piezoelectric disk is extremely low and performances obtained are being acceptable. Finally, this manufacturing technique is applicable for any crystalline piezoelectric salt.

FIGURE 1 .

 1 FIGURE 1. Illustration of the manufacturing process flow of the RS/PLA piezoelectric samples (diameter 25 mm, thickness: 2.5 mm).

FIGURE 2 .

 2 FIGURE 2. Conductance and susceptance spectra of 2.5 mm thick RS/PLA manufactured sample.

FIGURE 3 .

 3 FIGURE 3. Resonant frequencies (fr [Hz]), quality factors (Q) and coupling


Nathalie Poupin

Marie Tremblay-Franco

Cécile Canlet

Aurélien Amiel

Didier Rémond

Laurent Debrauwer

Dominique Dardevet

Fabien Jourdan

Isabelle Savary-Auzeloux

Sergio Polakof

Didier Remond

Modelling intrahepatic metabolic rewiring during the onset of obesity using arterio-venous blood metabolomics profiles

Keywords: metabolic networks modelling, flux analysis, NMR, arterio-venous differences, obesity, mini-pigs

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Introduction

General introduction to biological or methodological context (500 characters maximum spaces included) The metabolite composition of the blood inflowing and outflowing a tissue reflects its metabolic function, with consumed (resp. released) metabolites being in higher (resp. lower) concentration in arterial inflow than venous outflow. The objective of this study was to perform a global metabolic profiling of plasma from incoming and outgoing hepatic vessels using NMR on high fat/high sugar (HFHS)-fed minipigs to explore how the hepatic metabolism is modulated during the onset of obesity [1].

Technological and methodological innovation 500 characters maximum spaces included

The originality of our approach was to translate NMR arterio-venous metabolic profiles into utilization and release fluxes that we integrated in a tuned hepatic genome-scale metabolic network model to simulate fluxes through intra-tissular metabolic reactions. By setting constraints on model exchange reactions to enforce uptake and release of metabolites fitting the experimental data and using in silico flux calculation methods we could predict associated changes in intrahepatic metabolic fluxes.

Results and impact 500 characters maximum spaces included

The interest and novelty of the presented approach is to take advantage of accessible circulating metabolites across a tissue to computationally predict rewiring in its metabolism and changes in consumed and released metabolites that could constitute biomarkers of intra-tissular metabolic modulations. Using this metabolic network modelling strategy, we predict that HFHS is associated with changes in tryptophan catabolism [2], which were further supported by biochemical and molecular analyses.