PRE-SUBMISSION MEETING PACKAGE
Section: Device Description
Solstice Lumina™ Continuous Glucose Monitoring System
SPONSOR
Solstice Biomedical Inc. 220 Westbrook Drive, Suite 400 Cambridge, MA 02142
A wholly owned subsidiary of Solstice Biomedical Devices Ltd. Unit 14, Liffey Innovation Park Chapelizod, Dublin D20 FX72, Ireland (CRO No. 648231)
U.S. Subsidiary and Intended 510(k) Holder: Solstice Biomedical Inc. (Delaware Corporation, File No. 7834291)
Pre-Submission Type: Q-Submission (Q-Sub)
Reviewing Division: Center for Devices and Radiological Health (CDRH) Office of Health Technology 2 (OHT2) Division of Chemistry and Toxicology Devices
Anticipated Product Code: QKQ (Electrode, Glucose, Subcutaneous) Anticipated Regulation Number: 21 C.F.R. § 862.1355 Anticipated Device Class: Class II Submission Type: Traditional 510(k) — System-Level Submission (Lumina C14 Sensor and Lumina R7 Reader/Transmitter)
PREPARED BY
Calderwood & Harkness LLP 1401 K Street NW, Suite 900 Washington, D.C. 20005
In coordination with
Pinnacle Regulatory Consulting Group LLC 9500 Medical Center Drive, Suite 210 Rockville, MD 20850
Date of Package: June 2025 Target Pre-Submission Meeting Date: August 14, 2025
CONFIDENTIALITY NOTICE: This document contains confidential and proprietary information of Solstice Biomedical Inc. and Solstice Biomedical Devices Ltd. This Pre-Submission Meeting Package is submitted to the U.S. Food and Drug Administration solely for the purpose of obtaining feedback in connection with a planned Traditional 510(k) premarket notification for the Solstice Lumina™ Continuous Glucose Monitoring System. The contents of this document, including all technical data, trade secrets, specifications, algorithms, and business information contained herein, are confidential commercial information exempt from disclosure under 5 U.S.C. § 552(b)(4) and 21 C.F.R. Part 20. Unauthorized reproduction, distribution, or disclosure of this document or any portion thereof is strictly prohibited. All rights reserved.
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1. Introduction and Purpose
The purpose of this section of the Pre-Submission Meeting Package is to provide the U.S. Food and Drug Administration ("FDA" or "the Agency") with a comprehensive description of the Solstice Lumina™ Continuous Glucose Monitoring System (the "Lumina CGM System" or "System") in support of a planned Traditional 510(k) premarket notification submission. This Device Description section is intended to furnish the Division of Chemistry and Toxicology Devices within the Office of Health Technology 2 ("OHT2") with sufficient detail regarding the design, construction, operating principles, and key performance parameters of the System to facilitate a productive Pre-Submission meeting and to enable the Agency to provide meaningful feedback on the planned submission strategy.
The Solstice Lumina™ CGM System comprises two principal device variants that are proposed to be submitted as a single integrated system under one Traditional 510(k): the Lumina C14 implantable continuous glucose monitoring sensor and the Lumina R7 wearable reader/transmitter. The System also includes a companion mobile application (the Solstice Lumina™ Mobile Application) and a single-use sensor applicator (insertion tool). Solstice Biomedical Inc. intends to submit these components as a unified system because they are designed to function together and are interdependent in delivering the intended clinical benefit of continuous glucose monitoring.
The Lumina CGM System is designed for the continuous monitoring of glucose levels in the interstitial fluid of persons aged 18 years and older with Type 1 or Type 2 diabetes mellitus. The System is intended to provide real-time glucose readings, trend information, and configurable alerts to assist patients and their healthcare providers in the management of diabetes. The Lumina CGM System is intended to be a prescription-use device capable of replacing fingerstick blood glucose testing for diabetes treatment decisions, including insulin dosing, subject to the clinical validation data to be submitted in the planned 510(k).
Solstice Biomedical Inc. notes that the Lumina CGM System has been commercially available in the European Union since September 2024 under EU Medical Device Regulation (EU MDR 2017/745) CE Certificate No. MCA-2024-07319, issued on September 12, 2024, by Meridian Conformity Assessment GmbH (Notified Body No. 0483). The System has been distributed in the EU member states, the United Kingdom (under the UKCA marking pathway), and selected additional markets since that time. Solstice Biomedical Devices Ltd., the parent entity, holds ISO 13485:2016 certification for the design, development, manufacture, and servicing of in vitro diagnostic and continuous glucose monitoring devices, also certified by Meridian Conformity Assessment GmbH.
With respect to the sponsor's prior FDA regulatory history, Solstice Biomedical Inc. is not a new entrant to the FDA regulatory process. The company previously obtained 510(k) clearance for the GlucoStrip RX-200 Test Strip Reader (510(k) No. K192847, cleared November 14, 2019, product code NBW, Class II). The GlucoStrip RX-200 is a handheld blood glucose meter designed for use with compatible test strips and remains commercially available in the United States. That prior clearance is cited here solely for the purpose of establishing Solstice's corporate pedigree and demonstrating the company's prior experience interacting with CDRH. The Lumina CGM System represents a significant evolution in the company's technology platform, moving from a traditional blood glucose test strip–based system to a next-generation continuous glucose monitoring platform employing a novel fourth-generation enzymatic electrochemical biosensor with a proprietary platinum-iridium electrode coating.
This Device Description section is organized as follows: Section 2 provides a system-level overview, including the system architecture, intended use, and indications for use; Sections 3 and 4 describe the Lumina C14 sensor and Lumina R7 reader/transmitter, respectively, in detail; Section 5 addresses the companion mobile application; Section 6 describes the software architecture, version information, and cybersecurity features; Section 7 explains the system operating principles and data flow; Section 8 provides a summary comparison to identified predicate devices; Section 9 addresses planned labeling; Section 10 lists applicable standards and guidance documents; and Section 11 provides placeholders for appendices containing supporting diagrams, photographs, tables, and matrices.
2. System Overview
2.1 System Architecture and Components
The Solstice Lumina™ CGM System is an integrated continuous glucose monitoring system designed to provide real-time, minimally invasive measurement of glucose concentrations in the interstitial fluid. The System consists of the following four principal components, which together form the complete monitoring platform:
1. Lumina C14 — Subcutaneously Implantable Continuous Glucose Monitoring Sensor. The C14 sensor is a single-use, disposable, ethylene oxide–sterilized biosensor designed for subcutaneous insertion into the posterior upper arm. The sensor employs a fourth-generation enzymatic electrochemical biosensor architecture utilizing Solstice's proprietary PtIr-4G (platinum-iridium fourth-generation) electrode coating technology. The C14 sensor is rated for a maximum wear duration of 14 days (336 hours). The sensor incorporates onboard electronics for signal acquisition, digitization, and wireless data transmission.
2. Lumina R7 — Wearable Reader/Transmitter Device. The R7 is an arm-worn wearable device that serves as the primary reader and signal processing unit for the Lumina CGM System. The R7 receives raw digitized glucose signals from the C14 sensor via Bluetooth Low Energy (BLE) 5.2, processes those signals through the proprietary LuminaPredict algorithm to produce calibrated glucose concentration values, displays real-time glucose readings and trend information on an integrated touchscreen, and transmits processed glucose data to the Solstice Lumina™ Mobile Application via a second BLE 5.2 link. The R7 also manages all user-facing alert and alarm functions.
3. Solstice Lumina™ Mobile Application (iOS and Android). The companion mobile application provides a secondary display platform for real-time glucose data, extended trend graphs, summary statistics, data logging, history review, and data sharing with healthcare providers or designated caregivers. The mobile application also serves as a conduit for firmware updates to the R7 reader.
4. Single-Use Sensor Applicator (Insertion Tool). The applicator is a disposable, single-use mechanical device designed for patient self-insertion of the C14 sensor into the subcutaneous tissue of the posterior upper arm. The applicator utilizes a spring-loaded mechanism to ensure consistent and repeatable insertion depth.
The following diagram illustrates the system architecture and data flow pathways among the four principal components:
[See Appendix A: System Architecture Diagram]
Figure 1. Solstice Lumina™ CGM System — Simplified Architecture Schematic
C14 Sensor → BLE 5.2 Wireless Link → R7 Reader/Transmitter → BLE 5.2 Wireless Link → Lumina Mobile App (iOS/Android)
The data flow within the Lumina CGM System proceeds as follows. The C14 sensor's enzymatic electrochemical biosensor element generates an amperometric current signal proportional to the glucose concentration present in the surrounding interstitial fluid. This raw analog signal is digitized by the C14 sensor's onboard electronics (controlled by Lumina Firmware v3.4.2). The digitized raw signal data is then transmitted wirelessly from the C14 sensor to the R7 reader/transmitter via an encrypted BLE 5.2 communication link. Upon receipt by the R7 reader, the raw signal data is processed in real time by the LuminaPredict algorithm (v2.1), which is embedded within the Lumina Reader OS (v2.1.0). The LuminaPredict algorithm applies signal filtering, noise reduction, baseline drift compensation, temperature compensation, and factory-calibration correction to compute a calibrated glucose concentration value in mg/dL. The calibrated glucose value, along with calculated trend arrow information and alert/alarm status, is then displayed on the R7 reader's integrated touchscreen. Simultaneously, the processed glucose data is transmitted from the R7 reader to the Solstice Lumina™ Mobile Application via a second encrypted BLE 5.2 link, where it is displayed and logged for subsequent review.
2.2 Intended Use Statement
The intended use of the Solstice Lumina™ CGM System is stated as follows:
The Solstice Lumina™ Continuous Glucose Monitoring System is intended for the continuous monitoring of glucose levels in the interstitial fluid of persons aged 18 years and older with Type 1 or Type 2 diabetes mellitus. The System is intended for prescription use and is designed to replace fingerstick blood glucose testing for diabetes treatment decisions, including insulin dosing decisions. The System is not intended for use in critically ill patients, pregnant women, or persons on dialysis.
This intended use statement is consistent with the scope of the anticipated product classification under 21 C.F.R. § 862.1355 (Glucose test system) and product code QKQ. The System is designed to meet the performance criteria set forth in the FDA's guidance document "Integrated Continuous Glucose Monitoring Systems" (September 2023), which establishes special controls and performance expectations for integrated continuous glucose monitoring (iCGM) systems.
The Lumina CGM System is a prescription-use device. It is intended to be prescribed by a licensed healthcare provider and used by the patient in both home and professional healthcare settings. The System is not intended for use by or on the following populations:
• Critically ill patients (e.g., patients in intensive care units or emergency departments where glucose management requires invasive monitoring)
• Pregnant women
• Persons undergoing dialysis treatment
• Individuals under the age of 18 years
These exclusions are consistent with the exclusions applied to the identified predicate devices and reflect the current scope of the clinical validation program for the Lumina CGM System.
2.3 Indications for Use Summary
The indications for use for the Solstice Lumina™ CGM System are summarized as follows:
Device Name: Solstice Lumina™ Continuous Glucose Monitoring System
Indications for Use: The Solstice Lumina™ CGM System is a continuous glucose monitoring device indicated for the management of diabetes in persons aged 18 years and older with Type 1 or Type 2 diabetes mellitus. The System continuously measures glucose concentrations in the interstitial fluid and provides real-time glucose values, glucose trend information, and configurable glucose alerts to the user. The System is intended for prescription use.
Measurement Range: 40–400 mg/dL
Sensor Wear Duration: 14 days (336 hours)
Rx Only
Solstice intends to submit a concise Indications for Use statement on FDA Form 3881 as part of the planned Traditional 510(k) submission. The specific language of the Indications for Use statement will be finalized in consultation with the Agency following the Pre-Submission meeting.
3. Lumina C14 — Implantable Continuous Glucose Monitoring Sensor
3.1 Physical Description
The Lumina C14 is a subcutaneously implantable continuous glucose monitoring sensor designed for insertion into the subcutaneous tissue of the posterior upper arm. The sensor assembly consists of two principal structural elements: (a) an on-skin housing module that remains on the surface of the skin during the entire 14-day wear period, and (b) a flexible sensor filament that extends from the underside of the on-skin housing through the skin and into the subcutaneous tissue to a depth of approximately 5 to 7 mm beneath the skin surface, where it is in direct contact with interstitial fluid.
The on-skin housing module contains the sensor's onboard electronics, including the analog front-end circuitry for amperometric signal acquisition, an analog-to-digital converter, a microcontroller running Lumina Firmware v3.4.2, a BLE 5.2 radio transceiver, and a miniaturized battery providing power for the full 14-day sensor wear period. The on-skin housing is secured to the patient's skin by a medical-grade adhesive patch that is integral to the sensor assembly and is applied at the time of sensor insertion using the single-use sensor applicator.
The physical characteristics of the Lumina C14 sensor are summarized as follows:
• Form Factor: Disc-shaped on-skin housing with integral subcutaneous sensor filament
• On-Skin Housing Dimensions (approximate): 35 mm diameter × 5 mm height
• Sensor Filament Length (subcutaneous): 5–7 mm (measured from the skin surface to the distal tip of the filament)
• Sensor Filament Diameter: Approximately 0.35 mm
• Total Assembly Weight (approximate): 6.2 grams (including adhesive patch and battery)
• Adhesive Patch Dimensions (approximate): 45 mm × 50 mm (elliptical)
The sensor housing is constructed from medical-grade biocompatible materials selected for both mechanical durability and patient comfort during extended wear. The outer shell of the on-skin housing is fabricated from a medical-grade polycarbonate blend. The adhesive patch utilizes a hypoallergenic, breathable medical-grade acrylate adhesive designed to maintain secure skin attachment throughout the 14-day wear period while minimizing the risk of skin irritation or sensitization.
The sensor filament is the critical sensing element and represents the core innovation of the Lumina C14 design. The filament is constructed with Solstice's proprietary PtIr-4G (platinum-iridium fourth-generation) electrode coating, which is deposited onto the filament substrate via a proprietary deposition process developed by Solstice. The PtIr-4G electrode coating and the multi-layer membrane architecture applied to the filament are described in detail in Section 3.2 below.
The Lumina C14 sensor is a single-use, disposable device. It is not designed or intended to be reused, reprocessed, or re-sterilized. The sensor is supplied in individually sealed, sterile packaging and is sterilized using ethylene oxide (EtO) sterilization to a sterility assurance level (SAL) of 10⁻⁶, as described in Section 3.7.
3.2 Sensing Technology — Fourth-Generation Enzymatic Electrochemical Biosensor
The Lumina C14 sensor employs an electrochemical detection principle based on amperometric measurement of the glucose oxidase (GOx)–catalyzed oxidation of glucose. The sensor utilizes a fourth-generation enzymatic electrochemical biosensor design, which represents the current state of the art in continuous glucose monitoring sensor technology.
The sensor filament incorporates a multi-layer membrane architecture designed to optimize glucose selectivity, sensitivity, linearity, stability, and resistance to electrochemical interferences. The layers of the sensor filament, described from the outermost layer (in contact with interstitial fluid) to the innermost layer (the working electrode surface), are as follows:
1. Biocompatible Outer Membrane. The outermost layer of the sensor filament is a biocompatible membrane composed of a medical-grade polyurethane-based polymer. This membrane serves as the primary tissue-contacting surface and is designed to minimize the foreign body response, reduce protein adsorption and cellular adhesion, and maintain a stable interface with the surrounding interstitial fluid throughout the 14-day sensor wear period.
2. Glucose-Limiting Membrane. Beneath the biocompatible outer membrane is a glucose-limiting (flux-limiting) membrane that regulates the rate of glucose diffusion to the underlying enzyme layer. The glucose-limiting membrane is critical for extending the linear measurement range of the sensor to 400 mg/dL and for preventing enzyme saturation at high glucose concentrations. The membrane is composed of a proprietary polymer blend optimized for glucose permeability characteristics.
3. Enzyme Layer (Glucose Oxidase). The enzyme layer consists of glucose oxidase (GOx) immobilized within a cross-linked polymer matrix on the sensor filament. The GOx enzyme catalyzes the oxidation of glucose in the presence of a redox mediator. In the fourth-generation biosensor design employed by the Lumina C14, electron transfer from the GOx enzyme to the underlying electrode is facilitated by a mediator compound that shuttles electrons directly from the enzyme's active site to the electrode surface, thereby minimizing oxygen dependence and improving sensor performance under varying tissue oxygen conditions.
4. Mediator Layer. The mediator layer is integral to the fourth-generation biosensor architecture. The proprietary mediator compound is co-immobilized with the GOx enzyme and facilitates direct electron transfer from the enzyme to the PtIr-4G working electrode. The specific identity and formulation of the mediator compound are proprietary to Solstice and will be disclosed in the confidential section of the 510(k) submission.
5. Interference-Rejection Layer. An interference-rejection membrane is incorporated beneath the enzyme and mediator layers and above the working electrode surface. This membrane is designed to minimize the oxidation of common electrochemical interfering substances (e.g., acetaminophen, ascorbic acid, uric acid) at the electrode surface, thereby improving the specificity of the glucose measurement.
6. PtIr-4G Working Electrode. The innermost functional layer of the sensor filament is the PtIr-4G working electrode. The PtIr-4G electrode coating is a platinum-iridium alloy deposited onto the sensor filament substrate via Solstice's proprietary deposition process. The PtIr-4G technology represents a key differentiator of the Lumina C14 sensor and provides the following performance advantages compared to conventional platinum electrodes used in prior-generation CGM sensors:
• Enhanced Catalytic Surface Area. The PtIr-4G deposition process produces a nanostructured surface morphology that significantly increases the effective electrochemical surface area of the working electrode relative to a smooth platinum electrode of equivalent geometric dimensions. This increased surface area results in a higher amperometric signal per unit of glucose concentration, improving sensitivity.
• Improved Signal-to-Noise Ratio. The platinum-iridium alloy composition and nanostructured surface of the PtIr-4G electrode provide an improved signal-to-noise ratio compared to conventional platinum electrodes, which contributes to measurement accuracy, particularly at low glucose concentrations where signal-to-noise performance is most critical.
• Extended Sensor Functional Life. The PtIr-4G alloy exhibits enhanced resistance to biofouling and electrochemical degradation compared to pure platinum electrodes, contributing to the stable sensor performance required to support the 14-day wear duration.
In addition to the working electrode, the Lumina C14 sensor filament incorporates a reference electrode and a counter electrode in a three-electrode electrochemical cell configuration. The reference electrode provides a stable electrochemical potential against which the working electrode potential is maintained, and the counter electrode completes the electrochemical circuit. The reference and counter electrodes are fabricated using silver/silver chloride (Ag/AgCl) materials.
The Lumina C14 sensor operates by measuring the glucose concentration in the interstitial fluid at the sensor filament tip. The sensor is designed to provide a new glucose reading at intervals of approximately one (1) minute, corresponding to the sensor's internal sampling frequency. Sensor readings are accumulated and transmitted to the R7 reader at defined transmission intervals via the BLE 5.2 communication link, as described in Section 3.4.
3.3 Sensor Performance Specifications
The key performance specifications for the Lumina C14 sensor, as designed and targeted for clinical validation, are summarized in the table below and discussed in the following paragraphs.
Measurement Range. The Lumina C14 sensor is designed to measure glucose concentrations in the interstitial fluid over a measurement range of 40 mg/dL to 400 mg/dL. Glucose values below 40 mg/dL will be reported as "LOW" and values above 400 mg/dL will be reported as "HIGH" on the R7 reader display and the mobile application display.
Mean Absolute Relative Difference (MARD). The overall MARD performance target for the Lumina CGM System is ≤ 9.0%, which is consistent with the performance criteria established in the FDA's guidance document "Integrated Continuous Glucose Monitoring Systems" (September 2023) for iCGM designation. MARD will be assessed through the planned pivotal clinical study, Protocol SBD-LUM-CL-001 (the "LUMINA-US" study), using venous blood glucose (YSI 2900 Stat Plus Glucose Analyzer) as the comparator reference method.
Consensus Error Grid Analysis. The target for the Clarke Error Grid Analysis is that ≥ 99% of all paired CGM-reference data points shall fall within Zones A and B of the Clarke Error Grid. This target is consistent with the performance criteria for iCGM systems as described in the September 2023 FDA guidance.
Sensor Functional Life. The C14 sensor is designed for a functional life of 336 hours (14 days × 24 hours per day). The sensor is intended to be worn continuously for the full 14-day period and then removed and discarded. The sensor is not designed for reuse. At the conclusion of the 14-day wear period, the R7 reader will notify the user that the sensor session has ended and prompt the user to remove the sensor and insert a new sensor.
Warm-Up Time. Following insertion of the C14 sensor into the subcutaneous tissue, the sensor requires a warm-up period of no more than 60 minutes before the first glucose reading is available. During the warm-up period, the R7 reader will display a warm-up indicator and will not provide glucose readings or alerts.
Operating and Storage Conditions. The C14 sensor is designed to operate over an ambient temperature range of 10°C to 45°C (50°F to 113°F) and a relative humidity range of 10% to 95% (non-condensing). The sensor should be stored at temperatures between 2°C and 30°C (36°F to 86°F) in its original sealed packaging until use. The sensor has an anticipated shelf life of 12 months from the date of manufacture when stored under the specified conditions.
3.4 Wireless Communication
The Lumina C14 sensor communicates with the Lumina R7 reader/transmitter exclusively via a Bluetooth Low Energy (BLE) 5.2 wireless data link. The BLE 5.2 protocol was selected for its low power consumption characteristics, which are critical for maximizing the operational life of the C14 sensor's miniaturized onboard battery throughout the 14-day wear period, as well as for its enhanced data throughput, range, and security features compared to earlier BLE versions.
The key wireless communication specifications for the C14 sensor's BLE link are as follows:
• Bluetooth Version: BLE 5.2 (Bluetooth Core Specification v5.2)
• Communication Range: Up to approximately 6 meters line of sight between the C14 sensor and R7 reader
• Data Encryption: All data transmitted between the C14 sensor and R7 reader is encrypted using AES-128-CCM encryption in accordance with the Bluetooth Core Specification v5.2 security requirements
• Data Transmission Interval: Sensor data is transmitted from the C14 sensor to the R7 reader at intervals of approximately 5 minutes; each transmission packet includes the accumulated one-minute sampling data acquired since the previous transmission
• Pairing Protocol: The C14 sensor is paired with the R7 reader via Near Field Communication (NFC) tap at the time of sensor initialization, followed by BLE secure pairing
In the event that the BLE communication link between the C14 sensor and the R7 reader is temporarily interrupted (e.g., due to the devices being separated beyond the communication range), the C14 sensor is designed to buffer sensor data internally for a period of up to 60 minutes. Upon re-establishment of the BLE link, the buffered data is transmitted to the R7 reader, and the LuminaPredict algorithm processes the backfilled data to reconstruct a continuous glucose trace for the period of disconnection.
3.5 Sensor Insertion and Applicator
The Lumina C14 sensor is inserted into the subcutaneous tissue of the posterior upper arm using a single-use sensor applicator (insertion tool) that is supplied with each individual C14 sensor unit. The applicator is a mechanical device designed for patient self-use in the home environment and does not require assistance from a healthcare provider for sensor insertion.
The applicator incorporates a spring-loaded insertion mechanism that drives the sensor filament through the skin and into the subcutaneous tissue at a controlled and consistent depth. The spring-loaded mechanism is designed to ensure reproducible insertion depth and angle regardless of variations in patient technique, skin thickness, or subcutaneous tissue characteristics. The insertion process is designed to be rapid and to minimize patient discomfort.
The applicator includes the following features:
• Single-use design: The applicator is not reusable and is discarded after sensor insertion.
• Safety mechanism: The applicator includes a safety lock that prevents accidental deployment of the insertion needle prior to intended use and prevents re-use after deployment.
• Insertion needle retraction: The applicator utilizes a retractable introducer needle. The needle is used to guide the sensor filament through the skin during insertion and is automatically retracted into the applicator body after the sensor filament is deployed, leaving only the flexible sensor filament in the subcutaneous tissue. The introducer needle does not remain implanted.
• Adhesive patch deployment: The applicator simultaneously deploys and adheres the C14 sensor's on-skin housing and adhesive patch to the patient's skin during the insertion process.
Detailed instructions for sensor insertion using the applicator will be provided in the device labeling, including the patient Instructions for Use, the Quick Start Guide, and illustrative diagrams. A summary of the sensor insertion instructions is provided in Section 9 of this Device Description.
3.6 Biocompatibility. The Lumina C14 sensor is classified as a device in prolonged contact with subcutaneous tissue, as defined by ISO 10993-1:2018 (Biological evaluation of medical devices — Part 1: Evaluation and review within a risk management process). Specifically, the C14 sensor falls within the following categorization:
• Contact Nature: Implant device — tissue/bone contact (subcutaneous)
• Contact Duration: Prolonged (greater than 24 hours and up to 30 days)
Based on this categorization, and in accordance with the biological evaluation endpoints specified in ISO 10993-1:2018 Table A.1 and the FDA's guidance document "Use of International Standard ISO 10993-1, 'Biological evaluation of medical devices — Part 1: Evaluation and review within a risk management process'" (September 2020), the following biocompatibility testing program has been developed for the Lumina C14 sensor:
All biocompatibility testing for the Lumina C14 sensor will be conducted by Whitmore Laboratories Inc., located at 1625 Shady Grove Road, Suite 300, Gaithersburg, MD 20878. Whitmore Laboratories is accredited by the American Association for Laboratory Accreditation (A2LA) under Certificate No. 3847.01 and holds ISO/IEC 17025 accreditation for the relevant test methods. The target date for completion of the full biocompatibility testing program for the C14 sensor is August 31, 2025.
In addition to the standard biocompatibility testing endpoints listed above, Solstice has identified specific biocompatibility considerations related to the PtIr-4G electrode coating used on the C14 sensor filament. The platinum-iridium alloy composition and the proprietary deposition process used to apply the PtIr-4G coating may present unique extractable and leachable profiles that require evaluation. Accordingly, Solstice has planned a comprehensive extractables and leachables analysis for the C14 sensor, to be conducted by Whitmore Laboratories in accordance with ISO 10993-18:2020 (Chemical characterization of medical device materials within a risk management process). The extractables and leachables analysis will evaluate the potential for chemical species to be released from the PtIr-4G electrode coating, the membrane layers, the adhesive materials, and the sensor housing materials under simulated physiological conditions. The results of this analysis will inform the biological risk assessment and will be included in the biocompatibility evaluation report submitted as part of the 510(k).
3.7 Sterilization. The Lumina C14 sensor is provided to the user in a sterile condition. Sterilization is performed using ethylene oxide (EtO) gas sterilization at a validated contract sterilization facility. The sterilization process has been validated to achieve a Sterility Assurance Level (SAL) of 10⁻⁶, in accordance with the requirements of ISO 11135:2014 (Sterilization of health-care products — Ethylene oxide — Requirements for the development, validation and routine control of a sterilization process for medical devices) and ANSI/AAMI/ISO 11135:2014.
The EtO sterilization cycle parameters, including gas concentration, temperature, humidity, exposure time, and aeration time, have been developed and validated by Solstice's contract sterilization partner. Sterilization validation documentation, including fractional cycle studies, half-cycle qualification studies, and routine process monitoring protocols, will be available for review in the planned 510(k) submission.
Ethylene oxide residual levels on the sterilized sensor are controlled to within the limits specified in ISO 10993-7:2008/A1:2019 (Biological evaluation of medical devices — Part 7: Ethylene oxide sterilization residuals). Routine residual testing is performed on each sterilization lot as part of the release testing protocol.
4. Lumina R7 — Wearable Reader/Transmitter
4.1 Physical Description
The Lumina R7 is a wearable reader/transmitter device designed to be worn on the patient's upper arm during the 14-day C14 sensor wear period. The R7 functions as the central processing and display unit of the Lumina CGM System, receiving raw digitized glucose signals from the C14 sensor, processing those signals through the LuminaPredict algorithm to produce calibrated glucose values, and displaying real-time glucose readings, trend information, and alerts to the user.
The arm-worn form factor of the Lumina R7 represents a deliberate design choice and a key differentiator from the primary predicate device, the NovaSense GlucoTrack NX-500 CGM System (510(k) No. K211034), which utilizes a handheld receiver. The arm-worn design of the R7 provides several practical advantages for the patient: it maintains consistent proximity to the C14 sensor (which is also located on the upper arm), thereby ensuring reliable BLE communication; it allows for continuous, hands-free monitoring without requiring the patient to carry and consult a separate handheld device; and it facilitates continuous alert delivery through haptic (vibration) feedback directly on the patient's arm.
The physical characteristics of the Lumina R7 are summarized as follows:
• Form Factor: Compact, low-profile wearable device designed for upper arm wear
• Dimensions (approximate): 48 mm × 38 mm × 12 mm (length × width × height)
• Weight (approximate): 28 grams (without arm band)
• Housing Material: Medical-grade polycarbonate-ABS blend with a soft-touch overmold (thermoplastic elastomer) on the skin-contacting surface
• Display: 1.4-inch color touchscreen (AMOLED) with capacitive touch sensing
• Battery: Rechargeable lithium-polymer battery, 380 mAh capacity
• Charging Interface: USB-C (magnetic pogo-pin connector with USB-C adapter cradle)
• Water Resistance: IP27 rating (protection against immersion in water up to 1 meter depth for up to 30 minutes)
• Attachment Mechanism: The R7 can be worn using either (a) a medical-grade adhesive patch (supplied with the device, replaceable) or (b) an adjustable elastic arm band (supplied with the device). The attachment mechanism is user-selectable based on patient preference and activity level.
The R7 reader is a rechargeable, reusable device designed to last for the duration of multiple sensor sessions. The rechargeable lithium-polymer battery provides sufficient operational capacity to power the R7 reader for at least 14 consecutive days on a single full charge, thereby covering an entire C14 sensor session without requiring recharging. Under typical use conditions, Solstice estimates that the R7 battery will maintain adequate charge for approximately 16 to 18 days, providing a safety margin beyond the 14-day sensor session duration. Recharging is accomplished using the supplied USB-C magnetic pogo-pin charging cradle, with a full charge time of approximately 90 minutes.
4.2 Display and User Interface
The Lumina R7 reader features a 1.4-inch color AMOLED touchscreen display that provides the primary user interface for real-time glucose monitoring. The display is designed for clear visibility under a wide range of ambient lighting conditions, including direct sunlight, indoor lighting, and low-light environments. The display features automatic brightness adjustment and a manual brightness override.
The R7 display presents the following glucose information to the user:
Real-Time Glucose Value. The current glucose reading is displayed prominently in large, high-contrast numerals in units of mg/dL. The glucose value is updated each time a new processed reading is received from the LuminaPredict algorithm, approximately every 5 minutes. Glucose values within the user's target range are displayed in a neutral color (white), values below the user-configured low glucose alert threshold are displayed in red, and values above the user-configured high glucose alert threshold are displayed in amber/orange.
Trend Arrows. Directional trend arrows are displayed adjacent to the glucose value, indicating the rate and direction of glucose change. The R7 displays one of the following five trend arrow indicators:
• ↓↓ — Rapidly Falling (glucose decreasing at a rate greater than 3 mg/dL per minute)
• ↓ — Slowly Falling (glucose decreasing at a rate of 1 to 3 mg/dL per minute)
• → — Stable (glucose changing at a rate of less than 1 mg/dL per minute in either direction)
• ↑ — Slowly Rising (glucose increasing at a rate of 1 to 3 mg/dL per minute)
• ↑↑ — Rapidly Rising (glucose increasing at a rate greater than 3 mg/dL per minute)
8-Hour Trend Graph. A graphical display of glucose values over the preceding 8-hour period is available on the R7 display, accessible by a single tap on the glucose value screen. The trend graph plots glucose values on the vertical axis (with the user's target range indicated by a shaded band) against time on the horizontal axis.
The R7 reader provides configurable hypo/hyperglycemia alerts and alarms, which are a critical safety feature of the Lumina CGM System. The alert and alarm system includes the following:
• User-Configurable Low Glucose Alert Threshold. The user (or the prescribing healthcare provider) can set a low glucose alert threshold within a range of 60 mg/dL to 100 mg/dL (default: 70 mg/dL). When the calculated glucose value falls below this threshold, the R7 reader issues an alert to the user.
• User-Configurable High Glucose Alert Threshold. The user can set a high glucose alert threshold within a range of 120 mg/dL to 400 mg/dL (default: 180 mg/dL). When the calculated glucose value exceeds this threshold, the R7 reader issues an alert to the user.
• Urgent Low Glucose Alarm. The R7 reader includes a non-configurable urgent low glucose alarm that is fixed at a threshold of 55 mg/dL. This alarm cannot be disabled or modified by the user and is designed to provide an urgent notification in the event of a clinically significant hypoglycemic episode. The urgent low glucose alarm is delivered with a distinct alarm tone, continuous vibration, and a full-screen visual alert.
• Rate-of-Change Alerts. The user can enable optional rate-of-change alerts that notify the user when the glucose rate of change exceeds a specified threshold (e.g., glucose falling or rising faster than a user-specified rate), even if the absolute glucose value has not yet crossed the low or high glucose alert threshold. These predictive alerts are designed to provide early warning of impending hypoglycemia or hyperglycemia.
The alert latency specification for the Lumina CGM System — defined as the maximum time from the C14 sensor reading event to the delivery of an alert notification on the R7 reader — is no greater than 5 minutes. This alert latency target accounts for the sensor data transmission interval, the LuminaPredict algorithm processing time, and the alert evaluation logic.
Alerts on the R7 reader are delivered through three modalities: audible alert tones, haptic vibration on the user's arm, and visual display alerts on the R7 touchscreen. The user can configure alert delivery preferences (e.g., vibration only, sound only, or both) through the R7 settings menu. The urgent low glucose alarm at 55 mg/dL always activates all three modalities and cannot be silenced until acknowledged by the user.
4.3 Wireless Communication
The Lumina R7 reader functions as the communication hub of the Lumina CGM System, supporting dual BLE 5.2 wireless communication links:
1. C14 ↔ R7 Link (BLE 5.2 Receiver). The R7 reader receives digitized raw glucose signal data from the C14 sensor via an encrypted BLE 5.2 link. This is the primary data acquisition link through which all glucose measurement data enters the R7 reader for processing by the LuminaPredict algorithm.
2. R7 ↔ Mobile App Link (BLE 5.2 Transmitter). The R7 reader transmits processed glucose data (calibrated glucose values, trend arrows, alert status) to the Solstice Lumina™ Mobile Application running on the user's compatible iOS or Android smartphone via a second encrypted BLE 5.2 link.
Both BLE communication links employ AES-128-CCM encryption in accordance with the Bluetooth Core Specification v5.2 security requirements. Authentication and secure pairing protocols are implemented on both links to prevent unauthorized access to patient glucose data.
The R7 reader also incorporates Near Field Communication (NFC) capability, which is used for the following functions:
• Sensor Initialization/Pairing. When a new C14 sensor is inserted, the user initiates the sensor session by tapping the R7 reader against the C14 sensor's on-skin housing. The NFC tap triggers the sensor initialization sequence and establishes the secure BLE pairing between the C14 sensor and the R7 reader.
• Device Information Retrieval. The NFC interface allows the R7 reader to read the C14 sensor's unique serial number, lot number, calibration code, and expiration date information from an NFC tag embedded in the C14 sensor housing.
4.4 Electrical and EMC Specifications
The Lumina R7 reader is powered by an internal rechargeable lithium-polymer battery with a nominal capacity of 380 mAh. The battery is non-removable and is designed to retain at least 80% of its original capacity after 500 full charge-discharge cycles, corresponding to a useful device life of approximately 2 to 3 years under typical use conditions.
The R7 reader is recharged using a USB-C compatible magnetic pogo-pin charging cradle. The magnetic pogo-pin connector ensures reliable electrical contact and ease of use while maintaining the water-resistance integrity of the R7 housing (no exposed charging port on the device itself). A standard USB-C cable and wall adapter are supplied with the R7 reader.
The Lumina R7 reader is designed and will be tested to comply with the following electrical safety and electromagnetic compatibility (EMC) standards:
• IEC 60601-1:2005 + A1:2012 + A2:2020 — Medical electrical equipment — Part 1: General requirements for basic safety and essential performance
• IEC 60601-1-2:2014 + A1:2020 — Medical electrical equipment — Part 1-2: General requirements for basic safety and essential performance — Collateral standard: Electromagnetic disturbances — Requirements and tests
EMC and electrical safety testing for the R7 reader will be conducted by Whitmore Laboratories Inc. at their facility in Gaithersburg, Maryland. Whitmore Laboratories provided a quotation dated March 3, 2025, for the full scope of EMC and electrical safety testing for the R7 reader, with an estimated total testing cost of $175,000. This quotation encompasses emissions testing (radiated and conducted), immunity testing (electrostatic discharge, radiated RF immunity, conducted RF immunity, power frequency magnetic fields, voltage dips and interruptions), and electrical safety testing (insulation, leakage current, mechanical hazards, temperature limits).
4.5 Biocompatibility — R7 Reader
The Lumina R7 reader is classified as a surface-contact device with intact skin contact. Based on the anticipated use pattern (worn on the upper arm during the 14-day sensor session with periods of removal for charging and hygiene), the contact duration is categorized as limited to prolonged, depending on the specific attachment method used (adhesive patch vs. arm band). For the purposes of biocompatibility evaluation, Solstice has conservatively categorized the R7 reader as a prolonged-contact, surface-contact (intact skin) device.
Based on this categorization, and in accordance with ISO 10993-1:2018, the following biocompatibility testing program has been developed for the Lumina R7 reader:
Biocompatibility testing for the R7 reader will be conducted by Whitmore Laboratories Inc. at the same facility and under the same A2LA accreditation as the C14 sensor biocompatibility testing program.
5. Solstice Lumina™ Mobile Application
5.1 Application Description
The Solstice Lumina™ Mobile Application ("Lumina Mobile App" or "Mobile App") is a companion software application designed for installation on compatible Tidewater Industries iOS and Severin Industries Android smartphones. The Mobile App functions as a secondary display and data management platform within the Lumina CGM System, receiving processed glucose data from the R7 reader via an encrypted BLE 5.2 communication link and providing the user with extended data visualization, analysis, and sharing capabilities beyond those available on the R7 reader's integrated display.
The Mobile App is currently designated as software version Lumina Mobile App v1.0.3. The Mobile App is intended for use in conjunction with the Lumina R7 reader and Lumina C14 sensor and does not function as a standalone glucose monitoring device. The Mobile App does not perform the LuminaPredict algorithm calculations; all glucose values displayed by the Mobile App are received from the R7 reader in their processed, calibrated form.
The Mobile App provides the following core functions:
• Reception and display of real-time glucose values from the R7 reader
• Display of trend arrows indicating glucose rate of change
• Display of real-time and historical trend graphs
• Configurable alert and alarm management (mirroring the alert settings on the R7 reader)
• Data logging and history review
• Summary statistics and glucose management reports
• Data sharing capabilities with healthcare providers or designated caregivers
• Firmware update conduit for the R7 reader
5.2 Mobile App Functionality
The Lumina Mobile App extends the data presentation and analysis capabilities of the Lumina CGM System beyond the R7 reader's 8-hour trend display. The Mobile App provides the following specific functional capabilities:
Real-Time Glucose Display. The Mobile App displays the current glucose value in mg/dL, along with the corresponding trend arrow and a color-coded indicator of the value's relationship to the user's configured target range. The real-time display on the Mobile App mirrors the information presented on the R7 reader display, with the glucose value updating each time a new reading is transmitted from the R7 reader.
Extended Trend Graphs. The Mobile App provides graphical trend displays for the following time periods:
• 24-hour view: glucose values over the preceding 24 hours
• 7-day view: daily glucose overlay for the preceding 7 days
• 14-day view: glucose trace for the current or most recent 14-day sensor session
• 90-day view: aggregated glucose data for the preceding 90 days (across multiple sensor sessions)
Summary Statistics. The Mobile App calculates and displays the following summary statistics for user-selectable time periods:
• Time in Range (TIR): percentage of glucose readings within the user's configured target range (default: 70–180 mg/dL)
• Time Below Range (TBR): percentage of glucose readings below the target range
• Time Above Range (TAR): percentage of glucose readings above the target range
• Average Glucose: mean glucose value over the selected time period
• Glucose Management Indicator (GMI): estimated A1C based on CGM glucose data
• Coefficient of Variation (CV): measure of glucose variability
Exportable Reports. The Mobile App can generate summary reports in PDF format that are designed for review by the patient's healthcare provider. Reports include standardized layouts with trend graphs, summary statistics, event logs, and alert history. Reports can be exported via email, secure messaging, or cloud-based healthcare data sharing platforms.
Push Notification Alerts. When the Mobile App is active and connected to the R7 reader via BLE, glucose alerts and alarms configured on the R7 reader are mirrored as push notifications on the user's smartphone. This provides an additional layer of alert delivery beyond the R7 reader's onboard alert modalities.
5.3 Platform Compatibility