Long-term non-enzymatic glucose sensor for an artificial pancreas

Period of Performance: 09/01/2017 - 08/31/2018

$530K

Phase 2 SBIR

Recipient Firm

Profusa, Inc.
South San Francisco, CA 94080
Principal Investigator

Abstract

Project Summary/Abstract Despite years of development, currently available continuous glucose monitors (CGMs) still lack good accuracy and reliability for short-term and particularly, long-term use in diabetes management. While insulin pumps work well, CGM remains the single largest hurdle to closing the loop of an artificial pancreas. The main obstacles to achieving a long-term, accurate CGM are instabilities in the sensing chemistry and the body?s immune response against the sensor ? specifically the foreign body response (FBR) ? leading to biofouling, inflammation, avascular fibrosis and sensing chemistry degradation. Additionally, current CGM systems in the market and under development are either bulky percutaneous probes or implantable devices encased in hard metals or plastics that become surrounded by an avascular tissue capsule over time or are taken up by immune cells (if nano-sized). In this Phase II SBIR, we propose to demonstrate the safety and feasibility of a minimally invasive, long-term, non-enzymatic glucose sensor produced using our novel, tissue-integrating ?smart? hydrogels that become part of the tissue they are sensing to overcome the FBR. The near infra-red (NIR) fluorescence of the ?smart? hydrogel modulates based on the glucose concentration and is detected non- invasively through the skin with an optical reader. The long-term, vascularizing nature of these hydrogel sensors provides exquisite capillary proximity to more than 1000 times greater sensor surface area compared to traditional electrochemical sensors, thereby overcoming the FBR and enhancing accuracy and longevity of glucose detection. The proposed CGM system contains no implanted electronics or hardware in the body. Profusa?s long-term goal is to develop a self-calibrating, injectable, soft hydrogel CGM with a minimum operational life of 3 months and a longer-term goal of 12 months with sufficient accuracy to enable an artificial pancreas. Moreover, because of the platform-nature of this technology, sensing moieties specific to other analytes (e.g. oxygen, lactate) can also be incorporated within the hydrogel matrix. Profusa?s tissue-integrating sensor platform has been demonstrated to be stable in the body for months to years and to provide superior sensing performance compared to solid, non-tissue integrating sensors. The overall focus of this proposal is to transition the 90 day in vitro success from Phase I to an in vivo pre-clinical model over 90 days. In addition to demonstrating safety and feasibility, we aim to improve human factors of our glucose sensors by engineering a significant reduction in sensor size (7/8 less volume to minimize materials placed in the body and injection needle size cut in half to minimize sensation upon injection). The ultimate objective is to achieve stable sensor response over 3 months with an error comparable to leading percutaneous continuous glucose monitors. Refinement of fluorescent tissue-intergrating sensors promises to open a whole new sensing modality for diabetes management and health monitoring.