SensiVida Medical Technologies is developing a minimally-invasive Allergy Test system based on MEMS transparent microneedles, image processing algorithms, and information technology that automatically creates Electronic Medical Records. SensiVida’s technology offers medical professionals a quantitative, painless option to today’s time-consuming and subjective testing consisting of the following:
- A disposable microneedle chip/cartridge that painlessly and rapidly administers allergens deposited or encapsulated onto each microneedle.
- A compact imaging module/digital imager that captures real-time allergic reactions and sends images and data wirelessly or via a USB interface to a computer.
- User-friendly software allows the user to monitor allergic reactions quantitatively with data including reaction kinetics. An e-medical patient record is automatically created which can printed or transmitted.
The company has developed fabrication technologies to produce transparent, high quality, tough microneedle structures that do not fracture during use and can be combined with unique sets of allergens. Figure 1 compares two SEM pictures of traditional “lancets” technology versus SensiVida’s microneedles (same magnification).
The complete system, including allergen cartridge, optical module, and software, is shown in Figure 2a. A computer screenshot showing the subject’s skin, as viewed through the transparent microneedle array, is shown in Figure 2b.
Several configurations for the allergen chip/cartridge have been described in SensiVida patent applications. The simplest involves a microneedle array individually coated with the set of allergens. Upon insertion into the subject, the aqueous interstitial fluid dissolves the allergen matrix, allowing it to diffuse into the skin, thereby triggering the highly localized allergic reaction. In another embodiment, encapsulated allergens are packaged 1:1 along with each microneedle and released upon actuation (see Figure 3). A removable film seals the packaged allergen array, keeping it sterile until it is ready to use.
SensiVida has also developed image processing algorithms that precisely measure reaction extent. A sequence of images showing various processing steps is shown in Figure 4, starting with the raw “wheal” image” and ending with a diameter value. The SensiVida Allergy Test system has received IRB approval for clinical testing as a “non-significant risk” device and should receive rapid 510k FDA approval. Product launch is planned for 1st Q 2012.
Another product in the SensiVida product family is an unobtrusive, wearable glucose monitoring system which uses a disposable microneedle needle array (Figure 5) having individually-monitored sensors that are actuated in accordance to the patient’s test schedule. Its uniqueness and advantage over the existing monitors are:
- automated measurements without bio-fouling or clogging;
- accuracy equivalent to fingerstick test since it is a direct chemical test;
- hygiene benefits since no blood is extracted;
- the test is virtually painless;
- reduced need for calibration compared to other continuous glucose monitors (CGM’s)
The glucose monitor will be comfortably worn (optionally) as a band or patch. At user-defined time intervals, each needle of the array is individually deployed by an actuator, causing insertion into the patient’s skin. The fine tips of each microlancet are coated with a glucose sensitive enzyme (e.g. glucose oxidase) that modifies the color of a dye via redox reactions. The glucose signal is optically read through the transparent needle by a light sensing system. The data are calibrated so as to represent actual glucose concentrations and displayed, stored, or transmitted depending on the application. A portion of the fabrication technology developed for our glucose sensors was funded by the Army Research Laboratories.
The process of microneedle actuation is shown in Figure 6. Figure 6a shows a cross-section of a microneedle in its inactivated state. The microneedle is inserted into the subject via mechanical actuation, as shown in Figure 6b, and read out using the optical system shown.
In addition to simply making light measurements, SensiVida has developed a unique way to increase the accuracy of its measurements by using multispectral imaging and image processing. Often, imprecise microneedle penetration, variations in the sampled tissue, and coating defects in the device can lead to inaccurate measurements. Due to the transparency of the sensing microneedle, images of the reagent color change can be analyzed spatially to select viable measurement regions (and ignore defective areas). This method has been successfully implemented using quartz microneedles coated with glucose-sensitive enzyme/reagent chemistry and a phantom model. A set of images (viewing into the needle through the quartz substrate) is shown in Figure 7. By selectively extracting pixel sets that exhibit the expected color change (using multispectral histogram analysis), significant improvements in accuracy and reproducibility are possible.SensiVida has also developed non-toxic enzyme chemistry exhibiting sufficient sensitivity to detect low levels of blood glucose e.g. 50 mg/dL (about 50 ppm glucose in water). The company has collaborated with Cornell University to achieve scientific understanding of glucose detection chemistry. Read full article at: http://www.engineering.cornell.edu/news/magazine/spring2011/features/baeumner.cfm
SensiVida Medical Technologies