## 3 Blockchain Technology in Healthcare  
As an emerging information security solution, blockchain technology can potentially protect various industries' sensitive data and end devices, including healthcare [10]. Blockchain technology provides a wide range of security functions and applications thathelps to protect the healthcare sector from cyber intrusions, such as cryptography, hash function, anonymity, and digital signatures [14]. With the development of smart healthcare systems, the healthcare industry started using low-powered IoT smart devices to collect medical information and store health records [14]. As IoT devices are low-powered, sensitive medical information can be susceptible to cyber intrusions. The healthcare sector is looking for a robust information security solution, and blockchain technology can be a successful solution [7]. The healthcare sector also faces privacy issues, data corruption, theft of sensitive medical information and physical device damages, which can cause extreme consequences to lives [13]. Apart from these, the healthcare sector also faces data overload concerns, as IoT medical devices collect and process a lot of medical data. Data overload may cause bottlenecks in healthcare applications and data transmission. Also, as healthcare data are highly sensitive, there may be concerns with third-party integrated protocols [14]. With increasing cyber security threats, third-party protocols may raise privacy concerns and information theft. Healthcare is a critical sector that deals with human lives, and data leakage or corruption may put lives at risk. Therefore, healthcare systems follow global standards. However, IoT systems still face global standardization concerns due to the ambiguity of ownership. The integration of multiple IoT devices becomes challenging in healthcare for standardization procedures [14]. Similarly, the integration of various devices can impede the adoption of IoT in the healthcare sector. This obstacle arises from the fact that the manufacturers of these devices have yet to establish a common framework for creating communication protocols and standards [15]. This concern also may cause data-protection concerns in healthcare. Most IoT smart devices use wireless connectivity as the primary data-transmission technology. The wireless connectivity uses primary data security features such as data encryption. However, due to the increment of cyber threats, wireless technologies are more prone to cyber threats, including packet sniffing, Wi-Fi jamming, encryption cracking, and Wi-Fi phishing [15]. Concerning these cyber security threats, blockchain technology offers enhanced security features that promise the protection of data transmission technologies. However, as blockchains use a variety of security and privacy protection features such as anonymity, cryptography, and hash functions, the respective concerns, including privacy, can be addressed. Also, blockchains use ledgers to store block transaction records that can be used for audit purposes [16]. Blockchain technology can be operated for a wide range of networking purposes, such as medical data collection, digitalized patient tracking, and Ambient Assisted Living Systems [16]. Blockchain technology provides an additional security layer on network connections, IoT end devices, and user accounts [17]. Most blockchain platforms are open-source, providing legal licenses to customize as per requirements [17]. Blockchain researchers can use these open-source blockchain platforms to develop numerous automated blockchain applications for commercial purposes. However, the integration of blockchain technology and low-powered IoT healthcare-based wireless networks can be challenging due to scalability limitations [17]. Blockchains typically require high network bandwidth, and the limitations of particular blockchain networks can increase the latency while decreasing the block transactions [17].