Something’s fishy…

Fish for thought

Feeling famished? How about devouring some fish head curry to quell your hunger? Before that, you need to know something fascinating about fishes! It is very common for one to discard fish scales before consuming the fish. Some of us just do not fancy the taste of it. If you are one of them, after reading this post, I’m sure you would think twice about discarding the scales!fish-head-curry

Ingestible electronics

Advancements in Science and Technology has led to the discovery of ingestible electronics.Ingestible electronic devices have the potency to avert many of the challenges associated with chronic implants such as the risk of infection, chronic inflammation, and costly surgical procedures because they are able to detect diseases early and thus improve treatment of diseases.

These include the production of pills that diagnose diseases and machines that dispense drugs inside the body so as to enhance the lifespan of mankind.Some examples of ingestible electronics include edible cameras, ingestible event monitors, and integrated smart drug delivery systems. Some biocompatible materials such as flexible biodegradable elastomers and melanin-based pigments are used for on-board energy storage in these devices.Developments in this field has enabled scientists to invent an edible battery.This power source that delivers a charge is eventually flushed out of the body.


Biological materials

Melanin, a pigment naturally found on the skin is used to create this battery, whereby it is able to pick up charged ions and soak up metals, like zinc, aluminum, and iron, allowing it to emulate a battery. This edible  battery is made up of melanin as a positive or negative electrode, in addition to manganese oxide, sodium titanium phosphate, copper, and iron, all found naturally in the human body.The battery is thus able to provide energy to a 5 milliwatt device for up to 18 hours, when 600 milligrams of active melanin material is used as a cathode. This is just sufficient to power an ingestible drug-delivery or sensing device.

This set-up is embedded in a digestible 3D-printed shell made of a gelatin material. Due to it’s biocompatibility,  even if the shell ruptures, the melanin and other components could actually be digested or processed by the body, without any side effects.


Development of the Nanogenerator

Using this as a motivation, scientists  from Jadavpur University in India, have created a battery-free generator using fish scales. This is anticipated to be the key to a biodegradable power source for ingestible devices in future.

There are 3 types of Nanogenerators, namely, Pizeoelectric, Triboelectric and Pyroelectric. In this research, scientists explored Pizeoelectric nanogenerators. Fish scales are rich in collagen, which has an exceptional property of being piezoelectric. This means that when the scales are exposed to any stress, they generate a charge.This piezoelectric property has allowed the scientists to make an energy nanogenerator that is biodegradable and yet small enough to be ingested.


The process

The scientists first collected hard, raw fish scales from a fish processing market, and then used a demineralization process to make them transparent and flexible.The collagens within the processed fish scales serve as an active piezoelectric element. A bio-piezoelectric nanogenerator, also known as an energy harvester was then produced by placing electrodes on both sides, and then laminating it. A bunch of collagen nanofibrils were hierarchically well aligned and self-assembled in the fish scales.


The outcome

This process produced a large piezoelectricity of about 5 pC/N.A clear, transparent piezoelectric generator that runs on gentle hand movements is thus established. A simple pinch of the scales lights up 50 LED bulbs, and the researchers were able to power up to 77 blue and green LED bulbs.



Take-away message

So, remember not to bin your fish scale biowastes, for it may come in handy for you to light up some bulbs during an experiment or even during an emergency such as a blackout!


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