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Feb 2017

Over the last decade I have been pursuing thin bilayer plastic films for use in high-volume, low-cost applications. These films are most frequently encountered in potato chip bags as a laminate of PET and PE plastic. Due to the large, inter-layer difference in thermal expansion coefficient, plastic bimorph films curl much more dramatically with temperature than traditional bimetallic strips. Numerous applications suggest themselves, for example, they might function as a low cost damper to vent hot air out of an attic in the summer, but shut to retain warm air during the winter. Or, convert an entire agricultural field into a cold-frame. Toys are another application, some of which reached the market in 2012.

In addition to responding to their environment, the bimorphs can be laminated to thin film heaters, and triggered electrically.

Below is a survey of our work, aggregated over the last decade. Questions or comments welcome- enjoy!

Patents and Papers

How to leverage high-volume low-cost thin-film food packages as bimorphs for industrial-scale applications.

G. Blonder, "Coffee Bags and Instinctive Materials- the path to ubiquity," in Active Matter, S. Tibbits and L. Kinney, Eds., Cambridge, MA: The MIT Press, to be published Fall 2017.



Replacing one layer is a bimorph with a composite contain phase-change material. Instead of the curvature changing smoothly with temperature, the film jumps abruptly at the transition. Useful in actuators and sensors.

Article at Materials Research Express
Preprint at arXiv of Physics


Demonstration of a "snap" transition in a plastic bimorph film. The lamination process traps stress in the film, breaking symmetry. The film expands when heated, inverting the disk's curvature but changing the axis of symmetry by 90 degrees.


Demonstration of a non-linear PCBM jump caused by the volume expansion of phase-change inclusions embedded in one layer of the film.

Some interesting related work (more coming soon):


A Type F PCBM. μPCM inclusions in both layers, but with two different phase transitions. So the film Flip-flops one direction and then the other, as each phase transition is triggered.

US7351467B2 Beverage safety lid

Priority 1999-11-17 • Filing 2004-08-23 • Grant 2008-04-01 • Publication 2008-04-01

To prevent consumers from drinking dangerously hot beverages, a plastic bimorph film covers the sipping opening of a cup's lip, blocking the opening until the temperature is safe.

Application US20130171378A1 Composite Structures that Change Shape in Response to Changes in Temperature

Priority 2011-11-16 • Filing 2012-11-16 • Publication 2013-07-04

[0007] Later inventions, such as is exemplified by U.S. Pat. No. 6,966,812 to Blonder, entitled Thermally Movable Plastic Devices And Toys, describes a more versatile construction that is responsive to changes in temperature. The Blonder

US8991026B2 Artificial flower novelty and its method of manufacture with Tucker International LLC

Priority 2010-01-06 • Filing 2011-01-06 • Grant 2015-03-31 • Publication 2015-03-31

Artificial flower that bloom in sunlight or heat, constructed from an all-plastic bimorph film.

US20030161972A1 Thermally movable plastic devices and toys

Priority 1999-11-17 • Filing 2003-03-03 • Publication 2003-08-28

Temperature sensor or thermometer comprised from an all-plastic bilayer film.

US6966812B1 Thermally movable plastic devices and toys

Priority 2001-08-22 • Filing 2003-01-28 • Grant 2005-11-22 • Publication 2005-11-22

Bimorph flaps control how much sunlight (solar insolation) pene
trates through a window.

US7887907B2 Thermally movable plastic devices

Priority 1999-11-17 Filing 2008-08-05 Publication 2011-02-15 Grant 2011-02-15

A rotating pinwheel style toy that is powered by sunlight causing a plastic bimorph to bend and unbalance the wheel




A flower, copper foil heater on PET/LDPE film. 3V DC power


Tripus rotating toy, powered by sunlight

Thermally activated door panel. Integrating a thin film copper foil heater onto the PET/LPDE laminate. 1.5V operation.

 A night light angel, plugged in to a 120VAC outlet, heat supplied by a 7W night light bulb, bimetallic flasher circuit


Worms. Bimorph film cut at 45 degree angle to built-in curl, resulting in a helical cylinder. Heated under a mild flood lamp.


Butterfly prototype, thin film copper heat on PET/LDPE. 3 VDC operation.


Flower Surprise Friends, sold by Tucker Toys in 2012 period.


Motion sensing night light, blooming flower.


Anemone, a rotating solar wheel


Brain with "worms" prototype


more details at gregblonder.com


Corral reef sculpture.




N:P:K 18:6:12

e uno plures


Building and Green Technology


Instinctive solar shade, bimorph roll inside thermopane window.


Instinctive attic vent model. House cavity heated to 110F. Note use of stiffener strips along edge of vents.



Array of vents, triggered (for convenience) with flood lamp.


Tests of Stainless steel foil/ plastic bimorphs for use as instinctive dampers in a brise soleil


Single damper, heating and cooling speed



Contact Greg Blonder by email here - Modified Genuine Ideas, LLC.