# Piezoelectric Effect of k-Carrageenan as a Tool for Force Sensor

## TL;DR

This paper explores using k-carrageenan hydrogel with iron oxide as a low-cost piezoelectric material for force sensors.

## Contribution

The novel contribution is demonstrating k-carrageenan hydrogel with α-iron oxide as a practical piezoelectric force sensor.

## Key findings

- The hydrogel film shows consistent response time to mechanical impact.
- Fatigue does not reduce the sensor's response speed over repeated use.
- Theoretical models align with practical results in predicting hydrogel behavior.

## Abstract

Natural polymers, polysaccharides, demonstrate piezoelectric behavior suitable for force sensor manufacturing. Carrageenan hydrogel film with α-iron oxide particles can act as a piezoelectric polysaccharide-based force sensor. The mechanical impact on the hydrogel caused by a falling ball shows the impact response time, which is measured in milliseconds. Repeating several experiments in a row shows the dynamics of fatigue, which does not reduce the speed of response to impact. Through the practical experiments, we sought to demonstrate how theoretical knowledge describes the hydrogel we elaborated, which works as a piezoelectric material. In addition to the theoretical basis, which includes the operation of the metal and metal oxide contact junction, the interaction between the metal oxide and the hydrogel surfaces, the paper presents the practical application of this knowledge to the complex hydrogel film. The simple calculations presented in this paper are intended to predict the hydrogel film’s characteristics and explain the results obtained during practical experiments. Carrageenan, as a low-cost and already widely used polysaccharide in various industries, is suitable for the production of low-cost force sensors in combination with iron oxide.