The Future of Flexible Heaters in EVs and Medical Technology

Flexible heaters are thin, bendable heating elements made by printing conductive and resistive inks onto plastic films. Unlike bulky wire-based heaters, these printed heaters are typically only 0.05–0.76 mm thick and can conform to complex shapes. For example, Butler Technologies notes their printed heaters have a “thin, flexible, and sometimes stretchable” form factor that can even flex with the human body.

These heaters are already used in apparel, aerospace, automotive, and medical devices, and demand is rising rapidly, especially as electric vehicles (EVs) and advanced medical technologies require compact, efficient heating solutions.

What Are Flexible Heaters?

Flexible printed heaters are essentially heating films. Conductive busbars and resistive ink patterns are screen-printed onto a polymer substrate (such as polyester, polyimide/Kapton, or thermoplastic polyurethane. When voltage is applied, these printed traces generate heat via Joule heating. 

By choosing inks and patterns precisely, engineers can tailor the heater’s performance. The result is an ultra-thin, bendable film heater that can be laminated onto fabrics, plastic panels, or even embedded within devices. Because they are so thin and flexible, these heaters can go in places traditional heaters can’t – for example, inside wearable garments or molded into car parts.

Flexible heaters come in two main styles: fixed-resistance heaters (with a nearly constant resistance) and PTC (positive-temperature-coefficient) heaters. PTC heaters use carbon-based inks that automatically limit their temperature – as the heater warms up, its resistance rises, preventing overheating. 

Butler Technologies and others offer both types: fixed-resistance printed heaters for controlled warmth, and PTC printed heaters that self-regulate to a set temperature. In practice, a printed flexible heater can be built as a thin stack of layers (adhesive, printed busbars, heating ink, cover film), much like a flexible circuit.

Key Benefits of Flexible Heaters

1. Ultra-Thin & Conformable

• Printed heaters are typically less than 0.1 mm thick.
  
• It can be seamlessly embedded under fabrics, within plastics, or on curved surfaces.
  
• Especially effective when printed on TPU films, it flexes and stretches with the surface.
  

2. Uniform, Efficient Heating

• Resistive inks are patterned precisely to avoid hotspots.
  
• Distributes heat evenly, increasing comfort and safety.
  
• Uses less power and supports low-voltage battery designs.
  
• PTC (positive temperature coefficient) heaters regulate temperature without external thermostats.
  

3. Lightweight & Portable

• Lack of bulky coils or metal components makes them ideal for portable devices.
  
• Operate efficiently on 12–24 V battery packs.
  
• Ideal for wearable applications, can be integrated into garments without affecting weight or comfort.
  

4. Safe & Durable

• Low-voltage operation reduces the risk of shock and fire.
  
• Washable and robust for textile-based or wearable uses.
  
• Printed with stable inks like silver or carbon for long operational life.
  
• PTC heaters automatically limit overheating.

Flexible Heaters in Electric Vehicles (EVs)

1. Battery Thermal Management

• Embedded printed heater films inside EV battery modules maintain optimal temperatures.
  
• Heating helps improve range and charging speed, especially in cold climates.
  
• Printed heaters conform to battery cell shapes for efficient, localized heating.
  
• Graphene-enhanced PTC inks heat quickly and self-regulate to prevent overheating.
  

2. Cabin and Seat Heating

• Thin, flexible heaters are installed under seat upholstery and inside steering wheels.
  
• Provides rapid, even heating for comfort with low power draw.
  
• Butler Technologies offers PTC heater designs ideal for automotive interiors.
  
• Helps extend EV range by replacing inefficient traditional heating methods.
  

3. Defrosting and Sensor Protection

• Flexible film heaters are used in windshields, mirrors, and camera housings to prevent fog and ice.
  
• Transparent heater layers provide quick, uniform defrosting without hotspots.
  
• Keeps LiDAR and cameras on autonomous EVs operational in all weather conditions.

Flexible Heaters in Medical Technology

1. Wearable Therapeutic Devices

• Integrated into braces, wraps, and garments to deliver heat therapy for pain relief and circulation.
  
• Printed heaters on TPU films conform to the body and remain flexible during movement.
  
• Lightweight and battery-powered, suitable for mobile or at-home therapy.
  

2. Patient Warming Systems

• Used in neonatal incubators, emergency blankets, and hospital beds to maintain body temperature.
  
• PTC materials ensure gentle, regulated heating without the risk of overheating.
  
• Thin-film design offers more comfort than traditional electric wire blankets.
  

3. Smart Bandages and Heating Pads

• Printed heaters integrated into bandages to promote wound healing.
  
• Custom shapes allow targeted heat delivery around injuries or surgical sites.
  
• Thermotherapy wraps combine compression with active heating.
  

4. Other Medical Applications

• Used in operating room garments, infusion fluid warmers, and diabetic foot therapy pads.
  
• Flexible heaters paired with sensors allow for real-time temperature control.
  
• Butler Technologies has pioneered applications like “wound recovery badges” with printed films.

Technological Trends and Future Directions

1. Advanced Materials

• New substrates (like Kapton) and conductive inks (like graphene) enhance performance.
  
• Improve durability in extreme conditions such as frequent washing or heat exposure.
  
• Future innovations may include biodegradable and stretchable printed materials.
  

2. Self-Regulating (PTC) Designs

• Heaters with PTC properties self-limit their maximum temperature.
  
• Improve safety by avoiding the need for separate thermostats.
  
• Heat up rapidly and stop drawing power once the target temperature is reached.
  

3. Smart Integration (IoT)

• Flexible heaters are now being combined with sensors and wireless modules.
  
• Enables real-time data transmission and closed-loop temperature control.
  
• Ideal for remote patient care and intelligent EV thermal management systems.
  

4. Miniaturization & Customization

• Advances in printing allow for smaller and more intricate heating layouts.
  
• Useful for specialized medical devices, wearables, or odd-shaped automotive parts.
  
• Supports prototyping and mass production using roll-to-roll processes.

5. Growing Markets – EVs and Medtech

• EV battery and cabin heating systems are major drivers of demand.
  
• Healthcare sectors increasingly use printed heaters in wearables, smart bandages, and patient warming devices.
  
• Flexible heaters address thermal needs in compact, energy-efficient ways, aligning with sustainability and innovation trends.

Butler Technologies’ Role in the Future of Flexible Heaters

Butler Technologies, Inc. is a recognized leader in the development of flexible printed heaters. With decades of expertise in printed electronics, the company designs, fabricates, and assembles custom thermal and interface solutions across industries.

What makes Butler Technologies stand out is its ability to create ultra-thin, stretchable heaters that can be discreetly integrated into garments, medical devices, and automotive interiors. These printed heaters offer targeted, uniform heat while remaining lightweight and flexible. Butler Technologies’ offerings include both fixed-resistance and self-regulating PTC heater options, suited for everything from wearable tech to industrial applications.

The company partners with automotive manufacturers and healthcare innovators to deliver custom heating solutions like seat warmers, therapeutic braces, and advanced wound care systems. A notable example includes the integration of Butler Technologies’ heater technology into Team USA’s Olympic jackets to provide athletes with consistent warmth in cold conditions.

With ongoing research into advanced materials and printing techniques, Butler Technologies is helping drive the next generation of heating solutions for electric vehicles and medical technology.

Flexible Heaters Driving Innovation in EVs and Medical Devices

As electric vehicles and medical wearables become more advanced, flexible printed heaters are proving to be a key technology. Their thin form factor, precise control, and energy efficiency support the growing need for lightweight, responsive thermal solutions.

Butler Technologies plays an essential role in meeting this demand. By enabling smarter thermal management in both mobility and healthcare sectors, the company helps bring comfort, safety, and performance to the next level of product design. Flexible heaters are no longer optional add-ons; they are integral to the future of intelligent, connected devices