A contact lens with built-in display: science fiction or not?

Recent progress in microsystems integration technology such as ultra-thin chip packaging, stretchable interconnections, thin-film batteries and organic photovoltaics makes it feasible to incorporate various electronic components and transducers in extremely confined spaces and inside flexible or conformable objects. Can this ultimately lead to a genuine display in a contact lens? The major outstanding issues are reviewed

Design and modelling of thermoformed displays for smart contact lenses

This paper explores the challenges regarding the thermoforming of a deformable guest-host liquid crystal display within a smart contact lens. Focus was given to the finite element modelling of its thermoforming, to find respective design rules. Such displays are thought to be used in vision correction applications (i.e. artificial iris)

A liquid crystal based contact lens display using PEDOT: PSS and obliquely evaporated SiO2

An active spherically conformed liquid crystal cell is presented comprising PEDOT:PSS as a transparent conductive layer and obliquely evaporated SiO2 as an alignment layer. To tackle compatibility issues with the SU8 processing needed for the spacers, an additional buffer layer was included in the fabrication process. The electro-optic response is inspected closely and a contrast measurement is given

Current commercialization status of electrowetting-on-dielectric (EWOD) digital microfluidics.

The emergence of electrowetting-on-dielectric (EWOD) in the early 2000s made the once-obscure electrowetting phenomenon practical and led to numerous activities over the last two decades. As an eloquent microscale liquid handling technology that gave birth to digital microfluidics, EWOD has served as the basis for many commercial products over two major application areas: optical, such as liquid lenses and reflective displays, and biomedical, such as DNA library preparation and molecular diagnostics. A number of research or start-up companies (e.g., Phillips Research, Varioptic, Liquavista, and Advanced Liquid Logic) led the early commercialization efforts and eventually attracted major companies from various industry sectors (e.g., Corning, Amazon, and Illumina). Although not all of the pioneering products became an instant success, the persistent growth of liquid lenses and the recent FDA approvals of biomedical analyzers proved that EWOD is a powerful tool that deserves a wider recognition and more aggressive exploration. This review presents the history around major EWOD products that hit the market to show their winding paths to commercialization and summarizes the current state of product development to peek into the future. In providing the readers with a big picture of commercializing EWOD and digital microfluidics technology, our goal is to inspire further research exploration and new entrepreneurial adventures

Actuation Of Droplets Using Transparent Graphene Electrodes For Tunable Lenses And Biomedical Applications

Variable focal length liquid microlenses are the next candidate for a wide variety of applications. Driving mechanism of the liquid lenses can be categorized into mechanical and electrical actuation. Among different actuation mechanisms, EWOD is the most common tool for actuation of the liquid lenses. In this dissertation, we have demonstrated versatile and low-cost miniature liquid lenses with graphene as electrodes. Tunable focal length is achieved by changing both curvature of the droplet using electrowetting on dielectric (EWOD) and applied pressure. Ionic liquid and KCl solution are utilized as lens liquid on the top of a flexible Teflon-coated PDMS/parylene membrane. Transparent and flexible, graphene allows transmission of visible light as well as large deformation of the polymer membrane to achieve requirements for different lens designs and to increase the field of view without damaging of electrodes. Another advantage of graphene compared to non-transparent electrodes is the larger lens aperture. The tunable range for the focal length is between 3 and 7 mm for a droplet with a volume of 3 μL. The visualization of bone marrow dendritic cells is demonstrated by the liquid lens system with a high resolution (more than 456 lp/mm). The Spherical aberration analysis is performed using COMSOL software to investigate the optical properties of the lens under applied voltages and pressure. We propose a prototype of compound eye with specific design of the electrodes using both tunable lenses and tunable supporting membrane. The design has many advantages including large field of view, compact size and fast response time. This work maybe applicable in the development of the next generation of cameras, endoscopes, cell phones on flexible platform. We also proposed here the design and concept of self-powered wireless sensor based on the graphene radio-frequency (RF) components, which are transparent, flexible, and monolithically integrated on biocompatible soft substrate. We show that a quad-ring circuit based on graphene transistors may simultaneously offer sensing and frequency modulation functions. This battery-free and transparent sensors based on newly discovered 2D nanomaterials may benefit versatile wireless sensing and internet-of-things applications, such as smart contact lenses/glasses and microscope slides

Electrifying catheters with light

Smart minimally invasive devices face a connectivity challenge. An example is found in intracardiac echocardiography where the signal transmission and supply of power at the distal end require many thin and fragile wires in order to keep the catheter slim and flexible. We have built a fully functional bench-top prototype to demonstrate that electrical wires may be replaced by optical fibers. The prototype is immediately scalable to catheter dimensions. The absence of conductors will provide intrinsic galvanic isolation as well as radio frequency (RF) and magnetic resonance imaging (MRI) compatibility. Using optical fibers, we show signal transfer of synthetic aperture ultrasound images as well as photo-voltaic conversion to supply all electronics. The simple design utilizes only off the shelf components and holds a promise of cost effectiveness which may be pivotal for translation of these advanced devices into the clinic