Over the past decade, modern technology has propelled efficiency enhancements at an exponential rate—even reducing the amount of effort required to interact with everyday staples like thermostats, appliances and entertainment systems. What used to involve the press of a button or turn of a knob now entails the subtlest touch of a finger, all thanks to the innovative functionality of capacitive switches and conductive sensors.

This revolution is largely being driven by today’s consumers, who increasingly prefer to manage personal productivity tasks via single-tap smartphone applications. It’s an efficiency trend that’s also overtaking the home appliance market, with demand for internet-connected home appliances continuing to rise. Statista currently projects that over 57% of U.S. residences will include at least one smart home device by 2024, and Grand View Research expects the global smart home appliance market to expand at an 8.6% compound annual growth rate from 2022 to 2030. At the same time, governments and consumers continue to push for more environmentally friendly designs and energy-saving sustainability.

As these developments intensify the spotlight on smart home appliances and their human-machine interfaces (HMI), Molex remains at the forefront of recent advances. One prime example: We’re helping today’s manufacturers create a variety of modern HMI more quickly and easily than ever, by leveraging the power of PEDOT—an acronym that stands for polystyrene sulfonate or poly (3,4-ethylenedioxythiophene). This new, groundbreaking technology is changing the game in intelligent appliance design.

To fully grasp why PEDOT is proving to be so advantageous, it first helps to understand how capacitive touch switches differ from traditional, mechanical and membrane switch technology. Because older membrane switch technology typically incorporates two layers of conductive traces, users need to press the switch hard enough to make these layers meet and thereby close the electrical circuit.

In contrast, capacitive touch switches work like conductivity sensors that are somewhat akin to smartphone touchscreens. Capacitance refers to the storing of an electrical charge. When an ungloved finger touches a capacitive switch—even lightly— the capacitive touch microprocessor recognizes the finger, then instantly actuates according to a preprogrammed command.

For years, Molex has kept a finger on the pulse of capacitive touch switch innovation because we recognize the innumerable customer benefits. These switches are highly adaptable and have no moving parts, so they’re long-lasting and can be programmed to control a diverse array of consumer devices and appliances. They can also be manufactured using several different techniques and substrates, either on a conventional printed circuit board (PCB) or a flexible printed circuit (FPC) like those made of polyimide or polyester.

The choice of materials, however, can introduce some significant limitations that PEDOT may help overcome. For example, early capacitive touch switches used Indium Tin Oxide (ITO) as a conductive alloy. Because ITO deposits as a transparent film, it’s great for switches backlit by a light-emitting diode (LED). Unfortunately, it’s also fairly brittle; so it doesn’t readily adapt to the complex shapes that characterize today’s consumer appliances. Additionally, it uses a somewhat expensive subtractive process wherein the layer of ITO is etched to create the necessary switch circuits.

While ITO remains the gold standard on touchscreens or where ultra-clear visibility is required, design engineers creating modern appliance controls have begun seeking additional options that offer dependable conductivity, transparency, flexibility and cost-saving process efficiencies. In all these areas, PEDOT paints a promising picture.

PEDOT’s longer formal name mirrors the fact that it’s equally long on design merits. This printable, liquid organic polymer was originally used as an anti-static agent for photographic film. Turns out that once dry, PEDOT remains exceedingly pliable. In addition:

• It offers design adaptability that’s responsive to touch.
• It’s deposited via an additive production process, which is more cost-effective and less wasteful than the subtractive method used with ITO.
• It’s nearly colorless and produces translucent circuits, making it ideal for backlit applications.
• It can be applied to transparent areas of a polyester substrate.
• It can handle high-temperature applications, such as the sensor functionality required for kitchen range cooktops.
• When combined with silver ink, it can be used to create complete circuits—achieving good optical transparency and electrical conductivity.

Owing to the impressive properties noted above, PEDOT sensors are the perfect choice to support a plethora of space-saving backlighting techniques that accommodate the streamlined shapes and specialized capabilities of today’s home appliances. PEDOT gives today’s manufacturers:

• The option to design curved appliance surfaces.
• The modern look and enhanced visibility of backlit keys.
• Appliance control keypad designs that preserve signal integrity while accommodating increasingly tight space constraints.

Because opportunities for adding responsive touch switches abound in the kitchen, bedroom, laundry room and elsewhere, PEDOT is becoming the premier choice for integrated smart home applications. Conductive sensors used in these instances need to offer versatility that withstands heavy interaction—providing a sleek-yet-functional appliance control aesthetic that seamlessly blends in while standing out. Where other compounds may prove too costly or fall short in this regard, PEDOT delivers.

The increasingly intelligent smart home and smart appliance arena demands smart technology that can capably keep pace. At Molex, our ongoing priority is delivering dependable yet versatile offerings that customers can mix and match to meet a variety of evolving applications and interconnect architectures. Our fully qualified PEDOT capacitive switch technologies help today’s appliance manufacturers and design engineers push the boundaries of what’s possible—bringing innovative functionality to market faster and putting efficient new capabilities at the consumer’s fingertips.

_References:

_{Smart homes penetration rate in the United States 2017-2025 · Webpage · 2021 · Statista
https://www.statista.com/forecasts/887639/penetration-rate-of-smart-homes-in-the-united-states}

_{Smart Home Appliances Market Size & Share Report, 2030 · Webpage
https://www.grandviewresearch.com/industry-analysis/smart-home-appliances-market#:~:text=The%20global%20smart%20home%20appliances%20market%20size%20was,rate%20%28CAGR%29%20of%208.6%25%20from%202022%20to%202030}

_PEDOT

_{Webpage·2020 · Clegg, Clegg
https://www.chemistryworld.com/podcasts/pedot/8229.article}

_{Printable silver nanowire and PEDOT
ACS Appl. Electron. Mater. 2020, 2, 4, 1000–1010}

_{Publication Date: March 18, 2020}

_{https://doi.org/10.1021/acsaelm.0c00061}

_{Copyright © 2020 American Chemical Society
https://pubs.acs.org/doi/10.1021/acsaelm.0c00061}