A Comparative Analysis of Capacitive Based Flexible Pressure Sensors

A Comparative Analysis of Capacitive Based Flexible Pressure Sensors Julia Pignanelli1, Dr. Simon Rondeau-Gagne2 and Dr. Jalal Ahamed3 Department of Biology, University of Windsor Department of Chemistry & Biochemistry, University of Windsor Mechanical, Automotive and Materials Engineering Department, University of Windsor This paper presents the material characterization of a flexible polymer for potential biomedical pressure sensing applications. The emergence of flexible, capacitive based pressure sensors with similar tactile sensing properties as human skin are highly desirable in many applications such as continuous cardiovascular monitoring, electronic skin and rehabilitation technologies [2,3]. Most of these sensors require high sensitivity, fast response time, flexibility and low cost. Due to flexible and foldable nature of the sensor, it can be integrated to artificial skin or imposed on the body surface. Among different sensing technologies, one promising method is through the use of micro-structured, flexible, dielectric polymers, for example PDMS (Polydimethylsiloxane). Micro-structures increase the sensitivity of the device. Current methods for constructing micro-patterns into the PDMS requires expensive and labor intensive methods such as photolithographic techniques and chemical etching, which lack low-cost and large-area compatible alternatives. The objective of this work is to construct and characterize a flexible capacitor pressure sensing device by using a simple, cost effective method of PDMS microstructuring as described by previously by Grzybowki et al. [1]. The PDMS was prepared by mixing 20 parts elastomer and 1 part curing agent. The rough structured PDMS is prepared by simply curing the polymer within an epoxy mold that incorporates a micro – pattern like design found within a commercially available tape [1]. The sample was placed in a vacuum for one hour at room temperature and then cured for another 24 hours at room temperature. Flexibility of the sensors is a key parameter related to sensor sensitivity. Flexibility can be measured by measuring the modulus of elasticity. Our test reveals the rough structured 20:1 PDMS modulus to be 1.29 MPa whereas the non-structured 20:1 PDMS modulus was found to be 2.90 MPa. The difference in moduli was not determined to be significant as expected since the structures are not changing the material property of PDMS. Through characterization and preparation of rough structured capacitive based PDMS pressure sensors, we hope to produce a capacitive sensing device with excellent detection sensitivity at a low cost and with a simple method of production. Refrences: Grzybowski, B., Qin, D., Haag, R., & Whitesides, G. (2000). Elastomeric optical elements with deformable surface topographies: applications to force measurements, tunable light transmission and light focusing. Sensors And Actuators A: Physical, 86(1-2), 81-85. Boutry, C., Nguyen, A., Lawal, Q., Chortos, A., Rondeau-Gagné, S., & Bao, Z. (2015). A Sensitive and Biodegradable Pressure Sensor Array for Cardiovascular Monitoring. Advanced Materials, 27(43), 6954-6961. Mannsfeld, S., Tee, B., Sltengerg, R, Chen, C.,,, Barman, S., Muir, B., Sokiloy, A., Reese, C. and Bao, Z. (2010). Highly sensitive flexible pressure sensors with microstrucutred rubber dielectric layers. Nature Materials, 9(10), 859-864

The Slot-Die Coating of Self-Healing Dielectric Materials for the Next Generation of Smart Sensors.

Printed electronics (PEs) have attracted a lot of attention over the past decades. The ability to formulate inorganic or organic materials into functional inks with the capacity to be printed onto various substrates presents many advantages, including the capability to be stretchable and conformable, and the potential to be cheaper than current electronics. Therefore, PEs have an enormous promise for enabling novel technologies in a broad range of applications. In a short time, many major advances have been made in this field, including, through the synthesis of conductive polymers, preparation of materials with self-healing properties, and synthesis of stretchable conductors. This project focuses on the printing of a new self-healing dielectric material, previously developed in our group, on a polyethylene terephthalate (PET) substrate through slot-die coating. By paying special attention to environmental impact and compatibility for industrial production, the deposition of this new electroactive material was performed through the control of numerous variables to develop a robust and reliable procedure for the printing of future electronics. Each parameter was individually adjusted, and the resulting films were completely characterized using multiple techniques. This paper will focus on the importance of printed electronics for the development of new technologies, and results from an in-depth characterization will be presented. Moreover, the utilization of the self-healing dielectric materials in fully printed sensors will also be discussed

Effect of Branched Polyethylene on the Mechanical and Electronic Properties of Semiconducting Polymers

With the rise of portable and implantable electronics, where objects and human are constantly connected, there is a need for materials that can used in electronic devices that have a good charge transport and eco-friendly properties while also being stable in various conditions. Directly inspired by biological tissues, next generation electronics have to be capable of being molded in different shapes and forms and, more importantly, being utilized directly on (or inside) the human body to enhance our connectivity to the environment. This means that the components required to design and fabricate the next generation electronics need to be electronically and mechanically robust, while possessing properties similar to that of our body. To address this challenge, our research exploits a combination of a DPP-based conjugated polymer with a low-molecular-weight and low boiling point branched polyethylene (BPE) that are physically blended to improve the mechanical properties of the semiconducting polymers. Using various characterization methods such as atomic-force microscopy, UV-vis spectroscopy and X-ray diffraction, we evaluated the effect of the branched polyethylene additive on the mechanical properties of the polymers. Interestingly, this additive was shown to reduce Young’s modulus, decrease crack propagation, reduce crystallinity, promote aggregation, and increase crack onset strain. Our new materials were used to fabricate organic field-effect transistors, critical components of modern circuits. This presentation will discuss the preparation and characterization of new conjugated polymer and soft materials blends, and will highlight the potential of our new materials for the preparation of next generation electronics and sensors

SUPRAMOLECULAR SELF-ASSEMBLY OF CONJUGATED POLYMERS FOR ELECTRONIC APPLICATIONS

SUPRAMOLECULAR SELF-ASSEMBLY OF CONJUGATED POLYMERS FOR ELECTRONIC APPLICATIONS Brynn Charron, Michael Ocheje and Simon Rondeau-Gagné* Conjugated polymers are a particularly interesting class of compounds with a wide variety of applications including use in organic electronics and nanomedicine. In most organic electronic devices, the performance and efficiency are mainly limited due to morphological issues and mechanical limitations. To address this challenge, our group focuses its research on the development of novel strategies for the improvement of electronic properties (charge transport) and mechanical properties (stretchability) in conjugated materials. Our strategy, based on the incorporation of functional groups which form dynamic interactions in the polymer network, allows for the optimization of the strain tolerance of the materials and performance enhancement of electronic devices after suffering from environmental stimuli. In this presentation, we will discuss the development and synthesis of new conjugated polymeric materials with improved mechanical properties and self-healing behaviors. Characterization of these materials by different techniques will be presented and application of these new materials in organic electronic devices will also be discussed