1: Introduction

Blockchain technology now offers excellent potential in the connected world such as information and communication technologies, and it is still expanding in various aspects. After the emergence of cryptocurrencies, blockchain technology gains massive popularity over recent years. Cryptocurrencies are the digital assets or currencies that can be used to exchange within different currencies on a digital platform (Wikipedia, 2020). Traditionally, there used to be third parties such as banks and companies which work as a mediator for exchanging currencies among participants. Due to the centralized nature of the traditional system, it had many security and financial challenges. These challenges led to the implementation of cryptocurrencies. It is found that there are more than 1500 currencies (CoinMarketCap, 2020). Bitcoin was among the first, which was controlled by a decentralized system constituting the first generation of blockchain technology known as blockchain 1.0 (Kuhn and Sommers, 1981).

Blockchain 2.0 is the second generation that was first introduced to implement the smart contract concepts and properties. Smart properties refer to the digital resources or assets. The proprietorship of these assets is controlled via a digital platform enabled by blockchain technology. However, the smart-contracts refer to software programs used to set policies regarding the management of smart properties. Some of the common examples of blockchain 2.0 in cryptocurrencies are Ethereum (Home, ethereum.org, 2020), NEO (Neo-project, 2020), and QTUM (Home—Qtum, 2020), etc.

Blockchain 3.0 is the third generation which is still under development. Presently, it is mainly focused on nonfinancial applications of various connected technologies. In the modern world, Internet of Things (IoT) has impacted our lives with many changes (Kumar and Mallick, 2018). IoT, a connected network of smart devices, allows them to generate massive data and exchange information (Al-Turjman et al., 2020). With the advent of such technologies and sharing data, there are still many challenges that are hindering its continued growth, such as security issues precisely. To tackle such challenges, blockchain technology shows excellent potential by offering a decentralized-based security system to protect data from outside forces.

Ranging from the financial applications to connected objects, blockchain technology also offers great potential in healthcare industry (Pradeep, n.d.). However, it is still a new player in the domain of healthcare. Therefore, experts need to figure out what the specific scopes are and use case scenarios in healthcare enabled by blockchain. What are the applications that have been already developed in healthcare industry based on blockchain technology (Zafar and Rajnish, 2012)? What are the challenges that are hindering its continued growth and how it can be improved?

2: Blockchain overview

Blockchain technology is a digital ecosystem which stores series of data that are time-stamped and unchangeable. Clusters of computers manage the record of data without the ownership of single entity or any third party (decentralized). Each set of record is interlinked to each other and is fully secured using the principles of cryptography. Don and Alex Tapscott, authors of Blockchain Revolution (2016), defines blockchain technology as a digital ledger which has an incorruptible ability to record everything of value such as financial transactions.

Fig. 1 explains how decentralized infrastructure differs from centralized infrastructure. In centralized infrastructure, all the devices or computers are interconnected, but at the same time, they are managed by a single authority which is an internet server in Fig. 1A. It means that these devices send a request to the internet server, which in return sends back the instructions or feedback for the operation. However, blockchain technology does not work like that because it is comprised of decentralized infrastructure which connects all the devices in a chain-like series, shown in Fig. 1B. Such a structure makes blockchain a unique technology. In centralized infrastructures, hackers can easily trace single authority server and leak data; however, in decentralized infrastructure (Blockchain technology), there is no single authority, hence making impossible to hack and leak the data.

3: Proposed healthcare monitoring framework

Our model comprises scenarios in which medical staff remotely monitor the health of patients outside the hospital. In this case, wearable medical devices and sensors can be attached to the patient in which parameters such as body temperature, blood pressure, oxygen saturation, and heart rate can be measured and compared to preexisting ranges. External sensors can also be placed around the patient's residence, which can detect a change in the environment, such as movement or surrounding temperature. This live evaluation of data allows for the systems to detect abnormalities and alert the medical staff in case of emergency. All of this data are then accumulated and permanently stored in a remote database which can then be accessed in the future by healthcare professionals to evaluate the health status of the patient. Since these data are personal and sensitive to all the pertaining parties, it needs to be stored securely and should only be accessed by authorized parties. The use of blockchain technology-based systems can achieve this.

Medical devices blockchain: Each patient is fitted with a set of medical devices that will be monitored by our model. The data collected by the medical devices are then stored in the medical devices blockchain. The dataset for the proposed model can also be achieved from online sources as shown in Table 2. Each patient has his own Medical Devices BlockChain configured.

Consultation BlockChain: The Consultation BlockChain shown in the architecture contains records of the patient's history. The Consultation BlockChain is then set up across hospitals, and it includes the patient's records. This way, the medical reports become easily accessible and are exchangeable between hospitals and health workers in a confidential and secure manner. In our case, two separate BlockChains are chosen because each serves its purpose as shown in Fig. 2. Data received from sensors need to be maintained during the period of treatment. Patient records must always be accessible throughout the patient's life.

Live monitoring device: It is a system that manipulates data continuously and scans through various information. It is used to alert (when necessary) the healthcare professional on standby.

Medical sensors: Data received from the medical devices and sensors attached to the patient are stored in the BlockChain through NDN paradigm. This means that we have established a hierarchy between the medical devices to enable communication between them.

Medical experts: Any healthcare staff is represented by a node (e.g., computer/device) in both Medical Devices BlockChain and Consultation BlockChain. They can access the data through the Live Monitoring System based on the data stored in the Medical Devices BlockChain.

Patient: The patient is also represented as a node (e.g., computer/device) in the Medical Devices BlockChain. The patient collects data from the attached medical sensors and transfers them to the Medical Devices BlockChain to store it in a ledger. This allows both users (patient and healthcare staff) to interconnect with each other.

4: Blockchain-enabled healthcare applications

Ranging from banking to supply chain logistics, it has also opened a new challenge in the healthcare industry (Fig. 3 and Table 3). Blockchain technology allows healthcare revolution to lead a digital transformation fast. There are various ways blockchain can change the healthcare industry:

• Pharmaceuticals: One of the most rapidly expanding industries in the medical and healthcare sector is the pharmaceutical industry. It delivers new and approved drugs to the consumer markets while also maintaining supplies globally. Tracking drugs is the biggest challenge this industry is facing currently, ending up with fraudulent drugs. Screening for fraudulent drugs can be time-consuming and also potentially be hazardous toward the health of the consumer, as they are not approved; 10% of the drugs sold worldwide are counterfeits of which 30% arise from developing countries, according to the World Health Organisation (WHO, 2020). The use of blockchain technology in tracking pharmaceuticals from producer to consumer can prove the authenticity of a drug and prevent consumers from a mass-produced medication that can lead to severe consequences. Hyperledger, which is a new project, uses blockchain technology to enhance the security of pharmaceuticals from supplier to consumer (SecuringIndustry, 2016). It records timestamps such as date of production and also tracks the supplies. Another method which prevents the use of counterfeit drugs is by the use of Digital Drug Control Systems, which is also blockchain based and monitors all stages of production and supply (Plotnikov and Kuznetsova, 2018).
• Neuroscience: The brain contains around 120 billion neurons that all interconnect and form different pathways that emit different signals. The brains neural activity can be mapped by complex sensors which can attach to regions of the head and calculate the electric impulses using complicated algorithms. All these data are stored in interfaces which can enable the user to control other pieces of technology such as drones, robotic limbs, and other neural-interactive technology through the use of blockchain systems. One example of neural blockchain technology is Neurogress (Neurogress, 2020), which uses impulses received from the brain and has a computer interface with Artificial Intelligence that assesses the information and can also learn from it and adapt to carrying out further actions. However, since it would require a massive amount of physical memory in a computer to store all the impulses from a brain, it will be almost impossible to carry out these functions. This is where the blockchain system steps in. It can form a decentralized system that can establish trust between other networks on the system which contain multiple different information over a broad user base which can also be easily accessed by the neural-interface, thus allowing full functionality. Of course, as technology improves as time goes on, different regions of the brain can be mapped, allowing for storage of a plethora of brain functions such as smell, taste, emotions, and memory. This can open up more doors to how humans can interact with artificial intelligence and be the next step in medical advancements and research.
• Genomics: There are about 20,000–25,000 estimated human protein-coding genes which are responsible for producing multiple variations of proteins (Erdmann and Barciszewski, 2010). This is an immense amount of data which becomes very huge load upon current computer databases. These variations are then stored on a central server which poses as a problem to users who want access to the data and also becomes a privacy issue as the server becomes a single failure unit. Illumina HiSeq X Ten, a genome storing platform, has reported being able to store the sequence of the genomes of estimated 18,000 humans per year (Illumina, 2020). This corresponds to approximately 2 petabytes of data per year. To store these amounts of data, a massive infrastructure will be required to be able to handle all these data. These problems can be fixed with the implementation of blockchain technology, as they are decentralized and can be accessed by the data users and owners.
• Healthbank: An innovation by a Swiss Digital Health startup company (HealthBank.coop, 2020) is another blockchain system that gives the patient control over their health records. With Healthbank, patients can keep a record of their history of medications, blood pressure, heart rate, sleeping patterns, etc., by integrating with other applications and wearables. This detailed information can give physicians and researchers alike a more detailed insight into patient history. Another feature of Healthbank is that patients can provide their medical records to researchers in which they can receive payment for the information provided. This approach makes Healthbank a trading platform in which researchers can obtain detailed patient information in exchange for financial benefits.
• Clinical research: Privacy, data logging and data entry and its integrity are vital aspects to clinical research and trials. However, their opacity and misuse of the consent of trial become an issue to the patients and other stakeholders alike, as they are not informed about the full extent of the trial and the data collected. Consent between patients, researchers and stakeholders is a dynamic process and all these entities in-between need to interface with one another in a more transparent form to give more precise results in a trial. Forming a decentralized data storing and sharing is the best way to establish this, or in this case, by adopting a blockchain system. This way, all information about the trials can be seen by all the participants in a more manageable and secure fashion. An example in such a blockchain system is Ethereum (Home, ethereum.org, 2020). This system is maintained by research organizations, regulators, pharmaceutical companies that would like to test their drug, and other management systems. This forms a type of interactive datastore that can be accessed by all parties, and the trials can be monitored.
• Electronic health records (EHR): In this generation, digitizing data and records and storing them have been implemented in daily life as a means for more straightforward accessibility in the future. EHR is the most widely used example of blockchain technology in healthcare applications. Medical records can be in multiple institutions, and future medical references need to check on patient history, but this leaves the information dispersed in different institutions. A patients EHR contains sensitive information which is accessed by specialists, and all of this transmission of information can be scattered. This can be hazardous to the patient and impede the quality of treatment if the information is not maintained and up to date. To prevent this, blockchain technology can be acquired to maintain and manage patient records in an encrypted manner that cannot be tampered with. This can allow for a more precise diagnosis. An example of blockchain technology is MeDShare (MedShare, 2020), which shares medical records among hospitals and researchers with utmost privacy and security, maintaining the integrity of the records. Another blockchain system is a prototype called MedRec (MedRec-m, 2020), which mainly allows the patient to take control over which institutions can view their highly sensitive medial data in an easy-to-understand manner. Each medical record contains a mark in the blockchain system which guarantees authenticity. The patient can then share the respective duplicated medical data containing the mark.
• Supply chains: Nowadays, a lot of medical companies are facing common security problems in their supply chains which are also affecting our healthcare industry negatively in terms of both business and patient care. The most affected sector in the medical industry facing such problems is pharma industries because of the kind of product they carry. Various drugs are being stolen from such companies and are being sold to consumers illegally. Blockchain technology can help pharma industries by offering close tracking of drugs in their supply chain and by eliminating falsified or fake medications. Many organizations in the world are carrying out various clinical trials and research activities to produce or check new drugs and medications. Blockchain technology can develop a single universal database gathering all the information and the data and make them available at one platform.
• Health insurance: One of the significant problems in the healthcare industry is insurance fraud. It happens when corrupt individuals claim their payable benefits based on their fake information provided. One can imagine how serious is this problem from statistics by Boyd Insurance reporting that Medicare fraud costs about 68 billion dollars each year in the United States. This cost can be minimized significantly if Blockchain technology is utilized in the infrastructure. It helps to force individuals and providers to enter personal information to be verified first, and then the data will be stored and made accessible to the health insurance companies (Blockgeeks, 2018). In this way, the data will be recorded and managed in decentralized infrastructure, making it impossible for hackers to leak information and make fake data. One of the examples found is MIStore (Zhou et al., 2018), which is also a blockchain-based system used for medical insurance storage.

5: Potential challenges

This section overviews the potential challenges that are hindering the continued growth of blockchain-based healthcare systems. These challenges are discussed as follows:

• Scalability: The most potential obstacle in blockchain healthcare is scalability. Limitations of the healthcare systems scalability are between the accessible evaluation abilities and the number of medical transactions (Xia et al., 2017).
• High costs: Blockchain-based healthcare applications increase development and operational costs. The healthcare sector needs to assess the total cost, which includes the development, operational, and deployment costs, to present to the stakeholders involved. Optimizing these costs can substantially reduce the overall cost (Krawiec and White, 2016; Stagnaro, 2017).
• Standardization: For a healthcare application to be successful, standardized protocols must be established (Azaria et al., 2016; Yang and Yang, 2017). This means that for data stored in a blockchain in the case of healthcare, the parameters of the information must be established such as what features, dimensions, and configuration can be sent toward the blockchain (Krawiec and White, 2016; Stagnaro, 2017; Linn and Koo, 2016)
• Cultural resistance: The current generation is more adapted to the use of paper-based medical records or, in some rare instances, introduced to some type of online health service (Yang and Yang, 2017; Stagnaro, 2017). Establishing a cultural change toward the use of blockchain-based healthcare applications may take some time to adjust and alter the understanding of other parties interchanging patient's data.
• Regulatory uncertainty: Creating a well-developed ecosystem between stakeholders and the current existing framework would be challenging for regulators to establish policies that would consider all the current regulations and the new regulations. Currently, the standards are already being put into place to preserve the nature of the user's medical records by the HIPAA (Health Insurance Portability and Accountability Act) (Edemekong et al., 2020).
• Security and seclusion concerns: Security is one of the biggest concerns in blockchain technology-based healthcare applications even though they do contain security features (Azaria et al., 2016; Yli-Huumo et al., 2016). However, proper security measures need to be implemented to protect sensitive information that can only be accessed by an authorized person (Puppala et al., 2016; Al Omar et al., 2017; Linn and Koo, 2016).
• Unwillingness to share: Stakeholders or other concerned parties, such as insurance companies, may not be inclined to share data with other parties (Beck, 2018; Mettler, 2016; Esposito et al., 2018). This may be due to the difference in service costs provided and the actual costs of the parties concerned. A sense of trust between parties must be established to have a smooth functioning healthcare system.

6: Concluding remarks

We have overviewed the interdisciplinary aspects of blockchain technology while discussing its evolution that started from financing applications such as cryptocurrencies. Later, blockchain technology got a colossal intention and popularity in the digital world. Being a decentralized nature, blockchain technology offers significant benefits such as security, privacy, data provenance, robustness, and optimized data management solutions.

As our healthcare systems are lacking in terms of security and privacy, blockchain technology can do a chief role by allowing its decentralized abilities to ensure full security and integrity for healthcare systems. Due to its peer-to-peer ability, blockchain can replace third-party service providers by enabling patients and medical workers to interact with each other in a more confidential and secure manner. Besides, the integration of machine learning/artificial technology along with IoT devices can also enhance the potentials of blockchain technology in healthcare applications. The whole idea in this work is to pinpoint these benefits and propose how these potentials could improve our healthcare industry.

Different blockchain-based healthcare applications are presented in this book chapter such as EHRs, clinical research, neuroscience, genomics, and health insurance claims. However, this technology is still a new player in healthcare industry. Therefore, there are some technical challenges that are hindering its continued growth. Finally, this book chapter has presented its potential challenges that must be considered very carefully during application designing and implementation.