The designs for the smart objects were based on a brochure for OE-A. The OE-A brochure used was a basic printed electronic circuit with four static LEDs. We took this design and made it more complex by creating circuits that allowed blinking and static lights. The circuit on the brochure is controlled by a button, while the designs we created are controlled by a touch sensor. The result is three complex printed electronic circuits, each one with a more intricate feature than the other.
Guided by our project leader, Ulrich Stöckle, our team was split into small groups to design and create each smart object. These small groups established goals and deadlines to ensure smooth productivity. In addition to working in groups, each team member took on specific roles, such as marketing or testing the functionality of the circuits, to ensure all facets of the project were met.
Product 1: Touchsensor + LED
This component can be integrated into a variety of print products, e.g. a brochure or a greeting card. It includes two printed dots, which when touched by two fingers can take the place of a mechanical button. From the electrical engineering standpoint, the user’s fingers are integrated into the circuit as a strong resistor. With the help of a single transistor, the current flow is strengthened, causing the connected LEDs to light up.
Product 2: Blinking LED Light System
The Blinking LED Light Sequence product shows the ability to control the flow of electricity in a printed electronic circuit by illuminating each LED individually in a desired order. This is made possible by the use of two resistors, one capacitor, and one transistor for each LED. For the product, a printed battery and button, four transistors, four capacitors, and eight resistors were utilized in order to light four LEDs in a sequence.
Touch Sensor + Blinking/Static LEDs
The product features blinking LEDs and static LEDs that can be activated with a touch sensor.
This more sophisticated component can be integrated into a variety of printed products, including brochures and annual reports, greeting cards and direct mail advertisements.
It includes two printed dots, which when touched by two fingers can take the place of a mechanical button. From the electrical engineering standpoint, the user’s fingers are integrated into the circuit as a strong resistor. With the help of a single transistor, the current flow is strengthened, causing the connected LEDs to light up.
In this example, the touch sensor is integrated in the nose of the plane. When touched, the LEDs in the rear lights of the car and the LEDs in the guide sticks light up.
At first, we made several tests using long silver or carbon lines. What this all amounts to is that silver lines can’t be used as a resistor because their conductivity is too good, which would cause very long lines for e.g. a 22k ohms resistor. On the other hand, carbon lines are difficult to print which highly reduces productivity.
As a result, we’ve printed PEDOT and bonded it with silver lines (see left image). This combination worked very well and the first measurement results provided us a linear correlation which offers the possibility to easily calculate the needed line length of PEDOT.
Problematic was the fact that a 470 ohms resistor needs to be 3,2mm long, a 22k ohms resistor needs a (theoretical) length of 149,79mm. This length would reduce the flexibility of the whole silver line layout.
Therefore, we changed the mesh for PEDOT printing from 77 to 150. This led to a lower conductivity and shortened the length of the PEDOT areas.
For the final layouts we prepared two different screens: One with a 77 mesh for 470 and 1000 ohms and another one with a 150 mesh for 10k and 22k ohms. All four resistors were integrated either into smart object 2 or smart object 3.
The following video shows the production process for our printed smart objects.
Our team consists of an international group of students all attending Munich University of Applied Sciences. This project was completed during the Summer semester of 2013. The group was headed by project leader, Ulrich Stöckle, who led the group throughout the semester.