MATERIALS AND COMPONENTS
Scalable Production of Self-Powered Printed Temperature Loggers Using Functional Inks
Saralon, based in Chemnitz (Germany) addresses challenges in printed electronics through specifically designed sets of compatible Saral Inks©. This innovative approach has the potential to facilitate widespread commercialization of printed electronics and reshape various applications and industries.
The promise of printed electronics is providing an alternative to the conventional PCB manufacturing model. This is still not the case as PE developers are printing conductive traces and assembling different PE components on them. These components are printed by other companies who are experts in their field, e.g. battery, sensor or display.
Current practices limit large scale produc- tion by PE industries to play their part in the market growth projected by the increasing demand for wanting everything smart, i.e. smart living. The only solution for mass produc- tion of PE smart objects is the integrated print- ing of all components on a single substrate. Development of more complicated printed electronic devices necessitates more cost, time and R&D efforts investing to find multiple water-, solvent- and UV-based functional inks that match each other and can be printed step by step during a troubleless process.
Saralon tackles these challenges by the development of specifically designed sets of compatible Saral Inks© for smooth printing of high value, high demand electronic applica-tions and transferring process know-how to the printers. A highly advanced PE application developed by integrated printing of Saral Inks© is a temperature logger with inbuilt battery, electrochromic (EC) display and NFC antenna (Figure 1)
Smart Logistics: Transparency is the Key Cold supply chain is a complex ecosystem with multiple stakeholders. Data visibility technology plays a crucial role in making all engaged parties from the beginning to the end responsible for accountability and consumer trust.
Temperature loggers record temperature data continuously for the given period of time and intervals to eliminate human error and provide more accurate data. At present, such loggers come in the form of conven-tional electronic devices. There are, however, intrinsic limitations due to the high-cost, dimensions, weight and other design related properties of USB thermo-loggers that make them difficult to be used on smaller sized package and parcels.
Designed to enable the low-cost and effortless large-scale production of disposable printed temperature loggers, Saralon provides a set of 13 functional Saral Inks©.
Figure 1. NFC data accessibility of temperature loggers printed by a set of 13 functional Saral Inks©
This tech-nology presents great opportunities for the printed electronics sector to produce smart labels and packages that allow free flow of data stream, risk identification and mitigation and ensuring integrity and compliance with regulatory expectations of pharmaceutical and food products as they travel through the cold supply chain. These printed temperature loggers are compact, flexible, lightweight and ultra-thin IoT devices, capable of autonomous power generation and data collection. Data is conveniently displayed on the EC display and subsequently accessed via NFC with no need for extra software or an app.
The specification of the printed temperature logger such as measuring range, accuracy, recording capacity and intervals can be easily customized.
Exploring the Technology from a Closer Perspective
As shown in Figure 2, Saralon combines a handful of key technical enablers to facilitate the integrated printing of temperature loggers with inbuilt power source, display and NFC antenna in-house.
SaralBattery Inks consist of seven inks to screen print Zinc-ZnCl2-MnO2 batteries on paper, plastic or blister foil. These batteries can be printed in series to increase the power allowing customized solutions. Notably, the ink set features a specially designed bar-rier layer between the anode and cathode, eliminating the need for a separate paper-placement process.
Saralon includes SaralBattery Inks as a part of the temperature logger ink set to eliminate the need for external battery attachment. Instead, the power source will be printed as an integral part of the production process
About Saralon
Saralon positions itself as industry leader in the development of functional and conductive inks as well as ready-to-use printed electronic boards for specific applications. Founded in 2015 as a start-up and based in Chemnitz (Germany), Saralon has continued to expand its portfolio of innovative solutions for prin-ted electronics. Since the seed phase, the TGFS, a technology start-up fund from the federal state of saxonia, has been sup-porting the company as a venture capital investor. In 2022, the specialty chemicals group Altana also became an investor. The Saralon GmbH ist led by its co-foun-ders Dr. Moazzam Ali as CEO and Steve Paschky as CMO. Saralon’s product port-folio consists of four product lines and services:
- Saral Inks©: A comprehensive range of individual conductive and functional inks.
- Saral Inks© Sets: Specifically designed and developed sets of compatible inks for effortless integrated printing of high value, high demand elec-tronic applications.
- InkTech: Know-how transfer includ-ing design files, printing guide and continuous professional support.
- Saral Electronics: Pre-printed func-tional boards produced by Saralon using Saral Inks©.
Figure 2. Temperature logger with embedded printed battery, NFC antenna and display (shown before lamination).
These are the components of SaralBattery Inks:
- Saral Silver 600A: Conductive silver ink with moderate electrical conductivity spe-cifically designed for printed batteries.
- Saral Carbon 700A: Multipurpose solvent-based carbon ink with very good adhe-sion on paper and plastic. Other inks are easily printed on top as no delamination of the carbon layer occurs.
- Saral Zinc 700: Zinc particles-based anode ink.
- Saral MnO2 800: Manganese dioxide particles-based cathode ink.
- Saral BatElectrolyte 700: A viscous zinc chloride electrolyte ink.
- Saral BatBarrier 600: Water-based ink to create a separation layer between anode and cathode layers. The printed layer, after drying, turns into a porous solid layer which is ionically conducting.
- Saral HotMeltGlue 800: Heat activated adhesive to laminate two sheets. The key advantage of this ink is that it works when heated above 100°C. As the glue is not active in room temperature, after print-ing and drying, the printed sheets can be stacked on top of each other.
SaralEC Display Inks is the other key solution to the development of printed temperature loggers. Main advantage of this new generation electrochromic display is its very low power consumption and therefore easily activation by printed battery or NFC. Four different Saral Inks© are incorporated to screen-print high contrast, flexible electro-chromic displays as an integrated part of the temperature logger printing process.
These are the components of the SaralEC Display Inks:
- Saral ConductingPolymer 700: Transparent and conducting polymer ink, suitable for plastic and paper.
- Saral ECElectrolyte 200: Ionically conducting electrolyte layer ink for electrochromic display.
- Saral ECBlocking 300: Transparent block-ing layer ink to define patterns in the electrochromic display.
- Saral Silver 700/Saral Silver 600A: Multi-purpose silver based electrically conducting ink.
Compact and Stable Structure by Saral Adhesive Inks:
Three screen-printable adhesive inks with distinctive functionalities are included:
- Saral HotMeltGlue 800: Its main function is to laminate the cathode and anode sides of the printed battery. This adhe-sive ink is solvent based, thermally dried and similar to all other components of a temperature logger ink set, simply screen printable.
- Saral SilverGlue Alpha 600: This two components silver based conducting ink is specifically developed to easily attach SMD components to paper, plastic and glass substrates.
- Saral Silver Glue Beta 700: An anisotropic silver-based glue to electrically intercon-nect two conducting surfaces. This func-tional adhesive ink is heat activated and suitable for both paper and plastic.
High functioning NFC antenna by Saral High Solid Content Silver Ink:
- Saral HSCSilver 600 is a fast drying high conducting silver ink with 86% solid con-tent, especially developed for antenna printing.
Author: Steve Paschky