How silicone films connected to gloves improves the quality of manual work

Materials World magazine
,
13 May 2019

An ultrathin silicone film fitted on a glove connects the physical hand to software that improves the quality of manual work. Shardell Joseph finds out more.

A new ultrathin flexible film has been created that acts as a sensor on the outside of a glove, forming a man-machine interface without the need for external sensors or cameras. Establishing a connection between worker and machine to improve accuracy and efficiency, the technology has been described as the latest in Industry 4.0.

A research team at Saarland University, Germany, introduced the smart glove which uses a relay system able to identify the position of the wearer’s hands and fingers, sending tactile signals to the wearer through pulses and vibrations.

‘We started this prototype just one year ago, integrating a sensor strip that goes along your finger, so if you bend your finger the sensor gets stretched,’ said research team lead Professor Steffen Hau. ‘Each joint on the finger has one sensor, so we can recognise the movement of each joint. With this knowledge we can connect to a computer and then have a virtual reality hand that has the same movement as the glove.’

Initially designed for production line workers carrying out complicated tasks in diverse technical fields, the ultra-lightweight and flexible film from an elastic polymer acts as both a sensor and an actuator.

The glove can simultaneously recognise an unintended hand motion/gesture, sending signals to the worker via the vibrations to alert them of the mistake, then rely data to the main computer where the worker can learn from the error. Flagging errors early on can avoid potentially costly mistakes as a result.

‘By tracking the movement of a worker’s hand, if something goes wrong it can give feedback to the worker or the person using the virtual reality,’ said Hau. ‘This means wearer is aware of something wrong going on and they can then check what they are doing.’

The researchers are continuing the development of this technology and plan to insert the sensors into the lining of the glove, to improve usability and aesthetic.

Dielectric elastomers

The ultrathin silicone films give the glove the functions of a flexible sensor and are known as a dialectric elastomer (DE). Representing a new family of electromechanical transducers, DEs are capable of undergoing large actuation stroke, which is usually unattainable with regular transduction technologies.

DEs consist of an elastomer film sandwiched between two compliant electrodes, resulting in a flexible capacitor. With the ability to be used in several applications, this allows the actuators and sensors to operate simultaneously, by exploiting the so-called self-sensing feature of the material.

‘The dialectric elastomer is a technology where you have a flexible capacitor, which you can mechanically deform. When you make a mechanical derformant flexible capacitor this changes the capacitance. This capacitance change can be related to the deformation so that that’s how you have the sensor,’ said Hau.

‘If you have a capacitor strip with an elastomer layer on both sides of the electrode and you pull on the elastomer strip, it gets longer. This means the area of the capacitor increases and the gap between the electrodes decreases. This causes an increase in capacitance.’

Motorless pumps and more

Dialectric elastomer actuators (DEAs) have many potential applications, some of which the team have been working on, alongside the glove.

Using DEAs, the researchers created motorless pumps and self-regulating valves – they can control the silicone film electrically and make it execute precise vibrations or pulses on demand, while monitoring its exact position and/or shape.

‘In the pump, you have a dialectric elastomer actuator, which can generate a movement,’ Hau said. ‘We then took a commercially available pump mechanism called a road membrane – when you push on it, the volume within the membrane gets smaller and when you pull on, it gets bigger again. This volume, which you can reduce or increase, is connected to the check valve to direct the flow into one direction.’

The silicone films’ ability to pulse or vibrate on demand or take on any required shape enables them to be precisely controlled. This can continuously vary the frequency of its motion, from a low, slow pulsing motion to high-frequency vibration. In the future, this responsive film could be used to assist assembly operators or technicians to sort components efficiently without human error.