Accurate , precise dispensing for wearable technology
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Consumer wearables , including smart watches and augmented reality glasses , have captured the imagination of many . One important market for wearable devices is medical and healthcare , where they fulfil a diverse range of functions , such as monitoring patient heart rate , oxygen levels , body temperature and respiratory rate . State of the art wearables have good reliability , precision and are compact . Here Peter Swanson , Managing Director of adhesives specialist Intertronics , discusses best practice for dispensing processes in wearable device manufacturing .
The comfort , flexibility and connectivity of wearables have been made possible through progress in sensor technology , power management and transmitter technology ; these advances in wearable technology require improvements to the production process . One important part of the assembly process is the dispensing of materials like adhesives , silicones , thermally and electrically conductive materials and greases .
Dispensing technology is required for numerous functions when manufacturing a wearable device , such as bonding batteries to the housing , the application of conductive pastes for thermal management , and the sealing , encapsulation and bonding of sensors . Many Micro-Electronic- Mechanical Systems ( MEMs ) are bonded or encapsulated with a suitable adhesive , and materials are also used to coat or underfill processors , attach and bond RFmodules and seal and bond actuators .
When manufacturing a medical device , it is important that all processes are reliable , consistent and can be validated . The industry requires manufacturers to have a good understanding of process variables , and to control them to create a robust procedure across all dispensing processes . Dispensing processes must be done accurately and repeatably .
DISPENSING IN ACTION To achieve the level of precision required , manufacturers can opt for progressive
pump technology , as it enables true volumetric dispensing . A progressive cavity pump typically consists of a singlehelix metal rotor and a double-helix hole in an elastomeric stator , which forms a sequence of small discrete cavities . These cavities progress through the pump as the rotor is turned , transferring the liquid . The output represents true volumetric dispensing — the amount of material is directly proportional to the number of rotations of the rotor , and is not affected by material viscosity , input pressure or ambient temperature .
One example technology is the eco- PEN330 preeflow dispenser , which enables the user to dispense volumes as small as 0.001 µ l within 1 %, 99 % of the time — a high level of repeatability and accuracy . It can be used for low or high viscosity materials , with or without filler content .
DISPENSING FOR DIABETES MANAGEMENT Medical wearable devices have huge potential for diabetes management . For example , in the US , the digital diabetes management market size has a compound annual growth rate of around 20 %. Examples of technologies include continuous glucose monitoring , smart glucose metres and closed loop systems .
One interesting example comes from a client of ViscoTec India , whose engineers created a closed loop system , consisting of a skin patch that measures blood glucose levels , a device that calculates the required insulin dose , and a smart pump that injects the dose . During the production process , the manufacturer required the precise dispensing of 0.7 microlitres of grease into a gearbox component of the electric motor in the insulin pump . These precise requirements were fulfilled with a preeflow eco- PEN330 .
AUTOMATING THE PROCESS In most wearable production processes , adhesive dispensing is automated to achieve a high degree of repeatability . Once the dispensing technology has been selected , manufacturers can repeat the application of materials with positional accuracy by incorporating a robot or other form of automation . Medical device manufacturers have several options to mechanise the process , which include rotary tables or simple 3-axis benchtop robots , usually at modest cost , right up to multi-axis robots with vision-based control and feedback .
As well as delivering productivity benefits from their speed , consistency and ability to run continuously , automation can enable results not possible manually . They can deliver rapid return on investment , particularly when precision and accuracy-based productivity gains are taken into consideration .
The use of wearable technology in consumer and healthcare applications is now widespread . To produce a compact , reliable and precise device that meets rigorous industry standards , manufacturers require a robust dispensing process . Working with an experienced adhesives and dispensing equipment supplier can help you to invest in suitable technology .
For more information , visit www . intertronics . co . uk