IDC Designs Multiple Sclerosis Monitor and Additively Manufactured Microfluidic Diffraction Device
UK-based product design company Industrial Design Consultancy (IDC) has completed two notable device designs. The first is an electronic multiple sclerosis (MS) monitor, its second medical design project for the University of London's Queen Mary college. The second is an additively manufactured plastic microfluidic device with embedded microchip.
The project with Queen Mary college was to produce a bio-sensor holder and base unit enclosure for monitoring the condition of those living with MS. The product analyses tiny blood samples and measures a specific protein marker, matrix metalloproteinase 9 (MMP-9), to indicate worsening MS. The product aims to benefit patients who are known sufferers of MS by detecting inflammation around nerve fibres before the onset of a clinical attack or a relapse. Patients such as these, on anti-inflammatory therapies, need continual monitoring as treatment is only partially effective. Usually, the only way to monitor inflammation in MS patients is by expensive routine MRI [magnetic resonance imaging] scans or the occurrence of visible symptoms. However, Queen Mary’s bio-sensor aims to provide an important home detection system which is low-cost and which will provide an early indication if therapies are not being effective. This product builds on the success of Queen Mary’s previous project with IDC, which developed a bio-sensor for detecting periodontal disease (also known as gum disease).
Working alongside Queen Mary and other partners, IDC was tasked with producing an ergonomic, aesthetic and practical design for both the base unit and the sensor holder. The base unit enclosure was enhanced with a splash proof membrane keypad and a hinged lid which allows the user to insert a disposable foam pad. This pad prevents the blood sample from evaporating during the analysis process. The removable waterproof sensor holder incorporates a ceramic heater, which maintains the temperature of the bio-sensor chip during the test procedure. The product uses a two-part design with a disposable capillary-fill sampling chip that plugs into the main unit via the heated holder during testing. A small blood sample is placed on the sampling chip, which once inserted must maintain optimum contact with the bio-sensor at a temperature of 37°C for testing.
One of the aims of the product was to develop a device that allowed data to be easily recorded and transferred. The final design included an SD card slot [SD stands for secure digital, the slot is used to transfer data from high density memory cards found in cameras and other electronic devices] and a USB connector on the side of the device, which allows test results to be exported for monitoring by a remote medical team and generation of long-term patient records.
IDC’s project manager Ryan Fenton commented, “We’re delighted that Queen Mary has come back to IDC to help deliver another new product. The team is at its best when bringing ground-breaking research to life with innovative new products.”
Microfluidics
IDC's microfluidic design is special because it has been produced using additive manufacturing. The level of detail on the device are as small as 150 µm, in build steps of just 17 µm.
The product has been developed by UK-based IDC Models, the rapid prototyping and model making division of IDC.
The work is said to have contributed to the development of a new approach to building flow cells for maintaining biological sample integrity during x-ray diffraction.
These new cells, designed by Dr Peter Docker of Diamond Light Source, the UK’s national synchrotron facility, take advantage of stereolithography (SLA), a form of additive manufacturing where liquid resin is hardened selectively to form a three dimensional shape. IDC Models refers to this process as the more general term of rapid prototyping (RPT).
Synchrotron is a particular type of particle accelerator used to analyse particles of matter at a molecular level.
Using RPT IDC Models have enabled the flow cell and all its internal channels and chambers to be included in a single build operation. RPT takes advantage of a turnaround time of days from concept through to testing, with at least an order of magnitude in cost saving. The particular flow cell (shown in figure 1) is to be used in tests where small angle diffraction is measured to give information about proteins.
The protein sample is placed in the small 1 mm hole inside the chip.
As the sample is exposed to x-rays, a buffer solution (used to stop the sample degrading) is released from reservoir one and flows over the protein sample to reservoir two. Due to scale, the flow of the buffer is primarily affected by surface area and not (as it would be in the macro world), by volume. This allows devices to be designed to give appropriate flow rates just by altering channel geometry.
A more advanced flow cell is currently being designed which will incorporate a pump (only 7 mm x 7 mm x 1 mm in size) that will allow the buffer solution to be pumped over the sample. Using RPT, this integration requires a small alteration to the CAD of the part being reprinted.
About the SLA process
Working with Diamond Light Source, IDC Models used their Viper stereolithography (SLA) machine, a 3D printer that constructs models by selectively hardening liquid resin, to produce the prototype.
The SLA process involves “slicing” a CAD model into cross-sections which are traced by high-power lasers onto the surface of the resin. The resin cures and hardens where it is exposed to the laser, allowing objects to be built up layer by layer. The SLA machine can produce minute components with feature sizes of 150 µm, in build steps of just 17 µm.
The external dimensions of the microchip in figure 1 are just 20 mm x 12 mm x 1.5 mm. Typical traditional methods of prototyping, including photolithography etching and bonding two halves together, were considered to be time consuming and a costly process given this microchip is still in its development stage. Having the flexibility of RPT allows for many more iterations and a more organic approach to design. IDC Model’s SLA machine was chosen to produce the prototype as its high degree of accuracy enables Diamond Light Source to understand the chip architecture, where the channels are best positioned and the exact sizing of the chip reservoirs required.
The microchip model was showcased in the USA at Nanotech 2013 on May 12-16, 2013—described as being the world’s largest nanotechnology event. Nanotech is said to deliver application-focused research from the top international academic, government and private industry labs. At the time of going to press, IDC Models expected the intricate design of the microchip to be of interest to fellow exhibitors and visitors.