1.1

International Year of Light

As stated in the light2015.org homepage, “IYL2015 (was) a global initiative adopted by the United Nations to raise awareness of how optical technologies promote sustainable development and provide solutions to worldwide challenges in energy, education, agriculture, communications and health.” An immense effort with 93 national nodes gathered around this initiative with the United Nations Educational, Scientific and Cultural Organization launching the event on 19 January 2015. Events celebrating the impact of light on the daily lives of people were held throughout the year to raise awareness of the nature of light and it impact on all aspects of life.

1.2

Michigan Light Project

In this context, the Michigan Light Project was established by a group of academics, industrialists, and artists to “demonstrate the amazing aspects of light and energy in society as well as promote awareness that the State of Michigan is a worldwide hub of light-related industry, culture, and art.” Their mission was to use IYL as a catalyst to increase collaboration among artistic, industrial, and educational groups in addition to encouraging the local “economy of light” in Michigan. Like many sister organizations, the Michigan Light Project sorted through a plethora of ideas about identifying a common set of goals and about how to meet them with reasonably tangible resources. Since the beginning, we wanted to design a low-cost activity that combined art and science in a way that was accessible to a diverse audience. After hours and many iteration, we designed the pinky-powered photon activity shown below in Fig. 1.

Fig. 1.

Examples of art created by participants. The LED “eyes” can flash, alternate or wink, depending on the touch.

1.3

Piezoelectricity – a novel way to generate light

Piezoelectric materials are substances that respond to an applied force by producing an electrical current or, alternatively, move when an electrical current is applied. Piezoelectricity has been observed in many organic and inorganic substances, including bone, silk, sugar gemstones, quartz and some man– made compounds. Piezoelectric substances are ubiquitous workhorses in toys and consumer products as sensors, spark igniters, audio speakers, touch pad elements, signal generators, etc., making piezoelectric components readily available and inexpensive. The phenomenon of piezoelectricity is an excellent topic for the elementary school science curriculum but has not always been demonstrable in the classroom. Moreover, we believe that by providing interested outreach visitors with a “take home” project or activity creates an opportunity for subsequent play and experimentation that is an essential aspect of science and science education.

Consequently, we used a simple circuit to produce visual feedback (LED light) in response to mechanical stress imposed on the piezoelectric element. The guitar “pickups” shown in Fig. 2, which normally are used to convert sound into an electrical signal, power the LEDs. A quick finger tap on the disk element or shake of our shake light produces a slight deformation of the piezoelectric element and a voltage spike that causes both LEDs to appear to flash. The circuit is encased in an artistic creation made by participants or placed in a container so they can take the entire unit home. Gently pressing and releasing the disk causes one LED to flash followed by the other LED. Virtually any two colors of LEDs can be flashed with this arrangement. The effect is most apparent under low light.

Fig. 2.

Image of piezoelectric musical instrument pickups as received. Note the lightly– colored piezoelectric ceramic on one side and wire leads. The plain brass metal surface is used as the touch pad.

For younger participants or where soldering is prohibited, we pre–assembled the circuit and allowed participants to select from a variety of LED colors. Older participants were encouraged to actually solder the electrical parts together and then create their own art design to enclose the completed circuit. The entire activity was used to interest and interact with the general pubic. Advanced participants were advised to harvest parts for advanced projects.

2.1

Piezoelectricity: Technical Aspects

Piezoelectric elements, commonly employed as guitar “pick-ups,” convert mechanical vibrations into electric energy. French physicists, Pierre and Paul-Jacques Curie, first discovered the piezoelectric effect in 1880¹. They observed it in quartz, tourmaline, and potassium sodium tartrate. Now, the piezoelectric effect is used in quartz watches, spark lighters for gas stoves, and guitar pick-ups. The most common material used for guitar pick-ups is PZT or lead–zirconate– titanate. The lead content is very small, but we recommend that it the element side is always placed down in this activity. For further reading on piezoelectricity, refer to references 2 and 3.

2.2

Learning Objectives

The learning objectives of this project were aligned with the Next Generation Science Standards (NGSS) for K-12 science education. The objectives were modified based on the intended audience. An example list of applicable standards are shown below in Table 1. For participants younger than 4^th grade, we focused on the idea that one can transfer energy from your fingers to the piezoelectric element and power the LEDs. We introduced the basic concept of electricity and connected it to their homes. After visiting a first grade classroom, we learned that many first grade students know about electricity because they discuss home safety. We taught them that this is a small amount of electricity when compared with a standard home electrical outlet.

Table 1.

Applicable Next Generation Science Standards

2.3

Materials

Besides the piezoelectric element, most materials for this project are available from local sources. An overview of the materials is shown below in Fig. 3.

Fig. 3.

Materials (row 1 – craft foam squares, craft foam rings, corrugated board and row 2 – piezoelectric guitar pickups, LEDs) used to create artful animals

The complete list of materials required for this project are described below in Table 2. The foam rings were created using a ring punch. It is also easy to use a circle punch such as the Friskar Circle Thick Materials Shape Punch available from a local craft store. We recommend a 1” diameter for the center and at least a 2” diameter for the outside. Other shapes such as stars or squares could be used on the outer perimeter as well.

Table 2.

Materials list for single pinky-powered photon animal devices; prices based on larger quantity order

Table 3.

Additional supplies needed for activity

Table 4.

Instructions summary for single build of pinky-powered photon animals

Ordinary piezoelectric guitar pickups 32 mm in diameter with Copper wire leads attached were ordered online from Aliexpress.com or an eBay supplier. Almost any size element will work, but be aware that their power output varies with size. Our budget was ~ 35 cents per element in quantity of 100, which is less than the cost of a battery. One-watt LEDs, in various colors, without heat sinks, were purchased online and all parts were used as received. Essentially, any LED will work and two LEDs, even of different colors, are required for each piezoelectric element. Scraps of a rigid plastic signage board Coroplast® were cut into ~10x 15 cm squares to be used as a base to support the piezoelectric element and prevent over bending, although a firm cardboard or other surface will also work. Rubber sheet foam ~2mm thick, packaged in multiple colors, was purchased from a craft and sewing shop, as well as an arbitrarily-selected paper die cutter that yields small foam rings. Small 2 oz. condiment containers were used to create shake flashlights. A soldering iron, Lead-free solder and flux are used to connect the components. Clear 2 inch packing tape, colored markers, school glue and super glue are also needed. Latex balloons or other membrane if making musical instrument.

2.4

Instructions

Start by soldering two LEDs in parallel with the piezoelectric element being careful to ensure that the polarity of the LEDs are in opposition, as shown in Fig. 4. The opposite polarity enables lights to flash on both the down and up motion of the piezoelectric element. Test the circuit by gently tapping on the element to cause one LED to flash followed by the other as the pressure is relieved. If only one LED is used or both LEDs are of the same polarity then the LEDs will stop lighting after just a few taps. Participants are shown examples of animal creations and allowed to select from the pre-cut foam pieces and lay out their creation using school glue. For the googly-eyed creatures shown in Fig. 1, rings and disks are cut from the sheet foam and are used to secure the piezoelectric element. Use super glue to seal the disk element, with the lightly colored piezoelectric material between the soft under cushion and Coroplast® sheet. This leaves the plain brass surface to function as a touch pad. This arrangement allows the element to be flexed slightly when tapped. The LED “eyes’ are arranged as desired and super glued. After decorating with markers or crayons, the entire piece should be covered with clear packing tape in order to extend the lifetime of the piezoelectric element. Since slowly pushing and releasing on the piezoelectric disk causes one and then the other LED to flash, rapid tapping causes both LEDs to appear lit at the same time.

Fig. 4.

Electrical diagram and components used by older participants.

Older participants are instructed on soldering to make electrical connections, and warned of the hazards of soldering (hot metal, solder fumes, etc.) followed by a demonstration. They select two LEDs of whichever color and are shown how to strip off ½ inch of insulation from the two wires on the piezo disk. We created a silicone rubber jig to hold the LEDs for soldering shown below in Figure 5. The yellow is ordinary craft silicone that has cured. The LEDs should be testing before complete soldering. If you cannot determine LED polarity by the markings, then solder on one LED to the two wire leads and test operation by gently tapping on the disk. You should see a brief flash and note that flashing seems to stop working with several of rapid taps. Connect the second LED; if you note a brief flash or both LEDs appear lit with rapid tapping, the polarity is correct. If not, reverse the LED. Properly connected the LEDs will appear to flash alternatively.

Fig. 5.

Soldering rig for easy soldering of the piezoelectric element leads. The paper clamps and bar hold down the LEDs. The yellow in the center is ordinary craft silicone that has cured.

Fig. 6.

(L) Shake flashlight made from a recycled condiment cup. (R) Plastic bottles cut to make drum. Here that are shown with balloons as the membrane.

A simple shake flashlight is made by enclosing the piezoelectric element is a fast food condiment container to make a shake-powered light. First, reinforce the connection between the piezoelectric element and the wire leads by adding a drop of super glue to the solder and wire connection on the piezo element, since this will function as the striker. This prevents the wire from breaking at the connection. Place the piezo in the container allowing enough wire inside the container for the element to flop when shook. Force the lid on leaving the LEDs outside. Holding the LEDs in their desired final position, use the clear packing tape to hold them in place and give the entire container a good wrap of tape to seal the completed unit. Shaking causes the piezo element to strike the container walls and illuminate the LEDs.

Do you need sound to go along with the light? Light-up drums and other sounders can be made from soda and other plastic bottles. Begin by cutting one or both ends off a strong plastic bottle for the drum body. The wires on the piezo should be reinforced at their weak point, as noted above. Be aware that allowing the wires to bend over a large radius will reduce wire fatigue and allow for a longer play life. Next, a balloon or other suitable membrane is cut and stretched across the opening to form a drumhead. The piezo element must be loose enough to flop and hit the membrane. Use tape or a rubber band to secure the membrane to the bottle. Castanets and other instruments are also possible.

2.5

Summary of Projects

The participants in this activity were very creative. Below in Figs. 7, 8 are examples of animals made. Common designs were mice, owls, snails, turtles, and humanoid creatures.

Fig. 7.

Prototype piezoelectric animals. From left to right: Snell the Snail, Oscar the Owl, and Maxwell the Mouse.

Fig. 8.

Participant animals. From left to right: Turtle, creature, and mouse

4.1

Making the Activity Age-appropriate

This activity can be scaled depending on the age of the intended audience. For the youngest participants, the shake lights are ideal because the piezoelectric element is sealed entirely within the condiment container. Although the youngest participants may miss the creativity of making a piezo animal, they are provided with a device that will last for a longer time. The youngest participants can still be involved in the creation of the shake light by choosing which color LEDs they want and help apply the final layer of tape to the outside of the container.

For slightly older participants, this activity can be scaled based on the skill level of the participants. For those who are mature enough, and if time allows, participants can be taught how to solder and create the piezo animal entirely themselves with minimal volunteer guidance. With younger participants, or when there is a large demand for the activity, all of the soldering connections between the piezoelectric elements and the LEDs can be prepared ahead of time.

4.2

Preparations and Logistics

For a smooth activity, we recommend that the majority of the LEDs are prepared ahead of time. We found that the majority of participants were not interested in the soldering it themselves even if we had the time to teach them. In a busy festival environment, participants wanted to quickly make their animal and move onto the next activity. It is also recommended to have the materials cut and sorted ahead of time with as extra on hand if possible. Multiple color options of foam as well as multiple colors of markers allows for creativity. We also recommend that there are examples made of possible animals available for people to see. Many participants, especially the younger kids, struggled with visualizing the final project if left by themselves. An example of a turtle or a cat or an owl is enough for the participants to realize that the LEDs can serve as “eyes” and the rest of the foam can be designed as they wish.

4.3

Education

In order to make this activity as educational as possible, we recommend that time is put into developing visuals for explaining the basic concepts of piezoelectricity, electricity, and LEDs. We used a foam-ball model of PZT to show how a crystal could experience electrostriction. Prepare ahead of time talking points for the anticipated different levels of scientific understanding of the participants. Furthermore, we recommend that participants are encourages to be creative and re-use their piezoelectric element for future projects.