HARVESTING ELECTRICITY FROM HUMAN HAIR 31 DEVELOPING AN ENERGY HARVESTING BIOELECTRICAL DEVICE USING HUMAN HAIR In order to harvest suffi cient power to run a low power electronic device, we connected eight individual devices in a series circuit. Each device was prepared with aluminum and copper electrodes. The eight device series circuit assembly was mounted on a glass rod (Figure 11). In Figure 12, we have shown the snapshots of the video showing the glowing of the video. The real-time video fi le is in the supplementary information. Next, we calculated the power output of such crude devices. The power plot is shown in Figure 13. DISCUSSION In summary, here we showed that hair behaves like a thermo-sensitive solid polymer electrolyte. When it is exposed to “water + heat”, it results in the mobilization of the inherent ionic charge carriers present in the biopolymer matrix, as well as results in the generation of large number of protons (between 50° and 80°C). By placing the hair or silk polymer between two dissimilar electrodes (with different electronegativities), we offer directionality to the ionic and proton charge carriers, thus deriving useful electricity to Figure 11. Hair bio-electrical device: (A) Eight devices are connected in as series circuit and the output is connected to a light-emitting diode (LED). (B) The series circuit of eight devices. (C) Glowing LED on ex- posure to water vapor. The LED has the following specifi cations. This is a very standard red LED. The lens is 3 mm in diameter, and is diffused. The features include the following: a. 1.8–2.2 VDC forward drop. b. Max current: 20 mA. c. Suggested using current: 16–18 mA. d. Luminous Intensity: 150–200 mcd.

JOURNAL OF COSMETIC SCIENCE 32 Figure 12. The snapshots of the video fi le showing a functional low-power electronic system deriving en- ergy from hair bioelectric device. Figure 13. Power plot from “hair bioelectric device” described in Figure 9. The graph shows average (n = 6) power plot. When we exposed the hair to water vapor we get 0.01 milliwatt of power as long as the exposure to water vapor continues. As soon as the supply of water vapor was stopped the power decreased sharply. Basic electri- cal power equation was used to obtain the plot: Power (P) = I V = R × I2 = V2∕R where power P is in watts, voltage V is in volts and current I is in amperes (DC), R is resistance in ohm. Power plot was developed using Device 2 (copper/aluminum). Since the hair polymer is fairly stable so the device exhibit signifi cant period of longevity. run solid-state electronic devices. Thus, hair functions as a natural thermoelectric mate- rial and could be used to derive electricity from waste, moist heat. When similar electrodes were used (Figure 7), we did not observe signifi cant voltage or current. Further, we observed a wobbling in the voltage values. This is possibly due to the