Technical Library | 2017-06-14 21:33:00.0
Flexible circuitry may be preferable to rigid circuitry in situations where space or weight is limited.
Technical Library | 2022-01-19 17:06:16.0
This work presents the design and the realization of a flexible front-end circuitry for electrochemical sensing with wearable devices. The hardware combines readout circuitry for amperometric and Open Circuit Potential (OCP) measurements. The sensing platforms are dedicated to lactate and lithium detection in sweat, hence allowing the monitoring of athletes under physical effort.
Technical Library | 2013-09-05 17:44:14.0
Surface plasmon polaritons (SPPs) are localized surface electromagnetic waves that propagate along the interface between a metal and a dielectric. Owing to their inherent subwavelength confinement, SPPs have a strong potential to become building blocks of a type of photonic circuitry built up on 2D metal surfaces; however, SPPs are difficult to control on curved surfaces conformably and flexibly to produce advanced functional devices. Here we propose the concept of conformal surface plasmons (CSPs), surface plasmon waves that can propagate on ultrathin and flexible films to long distances in a wide broadband range from microwave to mid-infrared frequencies.
Technical Library | 2020-01-15 23:54:34.0
Flexible electronics has significantly advanced over the last few years, as devices and circuits from nanoscale structures to printed thin films have started to appear. Simultaneously, the demand for high-performance electronics has also increased because flexible and compact integrated circuits are needed to obtain fully flexible electronic systems. It is challenging to obtain flexible and compact integrated circuits as the silicon based CMOS electronics, which is currently the industry standard for high-performance, is planar and the brittle nature of silicon makes bendability difficult. For this reason, the ultra-thin chips from silicon is gaining interest. This review provides an in-depth analysis of various approaches for obtaining ultra-thin chips from rigid silicon wafer. The comprehensive study presented here includes analysis of ultra-thin chips properties such as the electrical, thermal, optical and mechanical properties, stress modelling, and packaging techniques. The underpinning advances in areas such as sensing, computing, data storage, and energy have been discussed along with several emerging applications (e.g., wearable systems, m-Health, smart cities and Internet of Things etc.) they will enable. This paper is targeted to the readers working in the field of integrated circuits on thin and bendable silicon; but it can be of broad interest to everyone working in the field of flexible electronics.
Technical Library | 2020-02-19 23:12:55.0
Silver nanowires (Ag NWs) possess excellent optoelectronic properties, which have led to many technology-focused applications of transparent and flexible electronics. Many of these applications require patterning of Ag NWs into desired shapes, for which mask-based and printing-based techniques have been developed and widely used. However, there are still several limitations associated to these techniques. These limitations, such as complicated patterning procedures, limited patterning area, and compromised optical transparency, hamper the efficient fabrication of high-performance Ag NW patterns. Here, we propose a coat-and-print approach for effectively patterning Ag NWs.
Integrated Microwave Packaging Antennas and Circuits Technology (IMPACT) Lab
Technical Library | 2019-01-10 10:24:47.0
We notice that the quantities of material that are to be dosed are becoming more and more divergent. In addition to large media volumes, small and very small quantities are also increasingly coming into focus. For example autonomous driving: These vehicles already produce an immense amount of data today. When potting the associated sensors, cameras, and ECUs, it is important to ensure a precise and repeatable media application – even with volumes of only 0.03 ml. In contrast, when high-voltage batteries for electric cars are potted, 5 to 10 litres of heat-conducting paste are required per vehicle – and the trend is rising. Optical bonding used in display production, on the other hand, is in the medium volume range. The challenge now is to cover the entire volume spectrum reliably and in compliance with the required cycle times. This is remedied by a modular system of scalable modules, which offers the customer the necessary flexibility and enables him to plan a system according to his needs.
Technical Library | 2020-07-29 19:58:48.0
The majority of flexible circuits are made by patterning copper metal that is laminated to a flexible substrate, which is usually polyimide film of varying thickness. An increasingly popular method to meet the need for lower cost circuitry is the use of aluminum on Polyester (Al-PET) substrates. This material is gaining popularity and has found wide use in RFID tags, low cost LED lighting and other single-layer circuits. However, both aluminum and PET have their own constraints and require special processing to make finished circuits. Aluminum is not easy to solder components to at low temperatures and PET cannot withstand high temperatures. Soldering to these materials requires either an additional surface treatment or the use of conductive epoxy to attach components. Surface treatment of aluminum includes the likes of Electroless Nickel Immersion Gold plating (ENIG), which is extensive wet-chemistry and cost-prohibitive for mass adoption. Conductive adhesives, including Anisotropic Conductive Paste (ACP), are another alternate to soldering components. These result in component substrate interfaces that are inferior to conventional solders in terms of performance and reliability. An advanced surface treatment technology will be presented that addresses all these constraints. Once applied on Aluminum surfaces using conventional printing techniques such as screen, stencil, etc., it is cured thermally in a convection oven at low temperatures. This surface treatment is non-conductive. To attach a component, a solder bump on the component or solder printed on the treated pad is needed before placing the component. The Aluminum circuit will pass through a reflow oven, as is commonly done in PCB manufacturing. This allows for the formation of a true metal to metal bond between the solder and the aluminum on the pads. This process paves the way for large scale, low cost manufacturing of Al-PET circuits. We will also discuss details of the process used to make functional aluminum circuits, study the resultant solder-aluminum bond, shear results and SEM/ EDS analysis.
Technical Library | 2020-10-08 00:55:22.0
This article presents the development of a stretchable sensor network with high signal-to-noise ratio and measurement accuracy for real-time distributed sensing and remote monitoring. The described sensor network was designed as an island-and-serpentine type network comprising a grid of sensor "islands" connected by interconnecting "serpentines." A novel high-yield manufacturing process was developed to fabricate networks on recyclable 4-inch wafers at a low cost. The resulting stretched sensor network has 17 distributed and functionalized sensing nodes with low tolerance and high resolution. The sensor network includes Piezoelectric (PZT), Strain Gauge(SG), and Resistive Temperature Detector (RTD) sensors. The design and development of a flexible frame with signal conditioning, data acquisition, and wireless data transmission electronics for the stretchable sensor network are also presented. The primary purpose of the frame subsystem is to convert sensor signals into meaningful data, which are displayed in real-time for an end-user to view and analyze. The challenges and demonstrated successes in developing this new system are demonstrated, including (a) developing separate signal conditioning circuitry and components for all three sensor types (b) enabling simultaneous sampling for PZT sensors for impact detection and (c)configuration of firmware/software for correct system operation. The network was expanded with an in-house developed automated stretch machine to expand it to cover the desired area. The released and stretched network was laminated into an aerospace composite wing with edge-mount electronics for signal conditioning, processing, power, and wireless communication.
Technical Library | 2020-07-22 19:24:33.0
Recent advancements in electronic packaging and image processing techniques have opened the possibility for optics-based portable eye tracking approaches, but technical and safety hurdles limit safe implementation toward wearable applications. Here, we introduce a fully wearable, wireless soft electronic system that offers a portable, highly sensitive tracking of eye movements (vergence) via the combination of skin-conformal sensors and a virtual reality system. Advancement of material processing and printing technologies based on aerosol jet printing enables reliable manufacturing of skin-like sensors, while the flexible hybrid circuit based on elastomer and chip integration allows comfortable integration with a user's head. Analytical and computational study of a data classification algorithm provides a highly accurate tool for real-time detection and classification of ocular motions. In vivo demonstration with 14 human subjects captures the potential of the wearable electronics as a portable therapy system, whose minimized form factor facilitates seamless interplay with traditional wearable hardware.
Technical Library | 2021-11-03 17:05:39.0
Additively printed circuits provide advantages in reduced waste, rapid prototyping, and versatile flexible substrate choices relative to conventional circuit printing. Copper (Cu) based inks along with intense pulsed light (IPL) sintering can be used in additive circuit printing. However, IPL sintered Cu typically suffer from poor solderability due to high roughness and porosity. To address this, hybrid Cu ink which consists of Cu precursor/nanoparticle was formulated to seed Cu species and fill voids in the sintered structure. Nickel (Ni) electroplating was utilized to further improve surface solderability. Simulations were performed at various electroplating conditions and Cu cathode surface roughness using the multi-physics finite element method. By utilizing a mask during IPL sintering, conductivity was induced in exposed regions; this was utilized to achieve selective Ni-electroplating. Surface morphology and cross section analysis of the electrodes were observed through scanning electron microscopy and a 3D optical profilometer. Energy dispersive X-ray spectroscopy analysis was conducted to investigate changes in surface compositions. ASTM D3359 adhesion testing was performed to examine the adhesion between the electrode and substrate. Solder-electrode shear tests were investigated with a tensile tester to observe the shear strength between solder and electrodes. By utilizing Cu precursors and novel multifaceted approach of IPL sintering, a robust and solderable Ni electroplated conductive Cu printed electrode was achieved.
